Merge tag 'nvme-6.9-2024-03-21' of git://git.infradead.org/nvme into block-6.9

[thirdparty/linux.git] / mm / vmalloc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Copyright (C) 1993  Linus Torvalds
 *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
 *  Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
 *  Numa awareness, Christoph Lameter, SGI, June 2005
 *  Improving global KVA allocator, Uladzislau Rezki, Sony, May 2019
 */

#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/set_memory.h>
#include <linux/debugobjects.h>
#include <linux/kallsyms.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/rbtree.h>
#include <linux/xarray.h>
#include <linux/io.h>
#include <linux/rcupdate.h>
#include <linux/pfn.h>
#include <linux/kmemleak.h>
#include <linux/atomic.h>
#include <linux/compiler.h>
#include <linux/memcontrol.h>
#include <linux/llist.h>
#include <linux/uio.h>
#include <linux/bitops.h>
#include <linux/rbtree_augmented.h>
#include <linux/overflow.h>
#include <linux/pgtable.h>
#include <linux/hugetlb.h>
#include <linux/sched/mm.h>
#include <asm/tlbflush.h>
#include <asm/shmparam.h>

#define CREATE_TRACE_POINTS
#include <trace/events/vmalloc.h>

#include "internal.h"
#include "pgalloc-track.h"

#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
static unsigned int __ro_after_init ioremap_max_page_shift = BITS_PER_LONG - 1;

static int __init set_nohugeiomap(char *str)
{
        ioremap_max_page_shift = PAGE_SHIFT;
        return 0;
}
early_param("nohugeiomap", set_nohugeiomap);
#else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
static const unsigned int ioremap_max_page_shift = PAGE_SHIFT;
#endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */

#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
static bool __ro_after_init vmap_allow_huge = true;

static int __init set_nohugevmalloc(char *str)
{
        vmap_allow_huge = false;
        return 0;
}
early_param("nohugevmalloc", set_nohugevmalloc);
#else /* CONFIG_HAVE_ARCH_HUGE_VMALLOC */
static const bool vmap_allow_huge = false;
#endif  /* CONFIG_HAVE_ARCH_HUGE_VMALLOC */

bool is_vmalloc_addr(const void *x)
{
        unsigned long addr = (unsigned long)kasan_reset_tag(x);

        return addr >= VMALLOC_START && addr < VMALLOC_END;
}
EXPORT_SYMBOL(is_vmalloc_addr);

struct vfree_deferred {
        struct llist_head list;
        struct work_struct wq;
};
static DEFINE_PER_CPU(struct vfree_deferred, vfree_deferred);

/*** Page table manipulation functions ***/
static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
                        phys_addr_t phys_addr, pgprot_t prot,
                        unsigned int max_page_shift, pgtbl_mod_mask *mask)
{
        pte_t *pte;
        u64 pfn;
        unsigned long size = PAGE_SIZE;

        pfn = phys_addr >> PAGE_SHIFT;
        pte = pte_alloc_kernel_track(pmd, addr, mask);
        if (!pte)
                return -ENOMEM;
        do {
                BUG_ON(!pte_none(ptep_get(pte)));

#ifdef CONFIG_HUGETLB_PAGE
                size = arch_vmap_pte_range_map_size(addr, end, pfn, max_page_shift);
                if (size != PAGE_SIZE) {
                        pte_t entry = pfn_pte(pfn, prot);

                        entry = arch_make_huge_pte(entry, ilog2(size), 0);
                        set_huge_pte_at(&init_mm, addr, pte, entry, size);
                        pfn += PFN_DOWN(size);
                        continue;
                }
#endif
                set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
                pfn++;
        } while (pte += PFN_DOWN(size), addr += size, addr != end);
        *mask |= PGTBL_PTE_MODIFIED;
        return 0;
}

static int vmap_try_huge_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,
                        phys_addr_t phys_addr, pgprot_t prot,
                        unsigned int max_page_shift)
{
        if (max_page_shift < PMD_SHIFT)
                return 0;

        if (!arch_vmap_pmd_supported(prot))
                return 0;

        if ((end - addr) != PMD_SIZE)
                return 0;

        if (!IS_ALIGNED(addr, PMD_SIZE))
                return 0;

        if (!IS_ALIGNED(phys_addr, PMD_SIZE))
                return 0;

        if (pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr))
                return 0;

        return pmd_set_huge(pmd, phys_addr, prot);
}

static int vmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
                        phys_addr_t phys_addr, pgprot_t prot,
                        unsigned int max_page_shift, pgtbl_mod_mask *mask)
{
        pmd_t *pmd;
        unsigned long next;

        pmd = pmd_alloc_track(&init_mm, pud, addr, mask);
        if (!pmd)
                return -ENOMEM;
        do {
                next = pmd_addr_end(addr, end);

                if (vmap_try_huge_pmd(pmd, addr, next, phys_addr, prot,
                                        max_page_shift)) {
                        *mask |= PGTBL_PMD_MODIFIED;
                        continue;
                }

                if (vmap_pte_range(pmd, addr, next, phys_addr, prot, max_page_shift, mask))
                        return -ENOMEM;
        } while (pmd++, phys_addr += (next - addr), addr = next, addr != end);
        return 0;
}

static int vmap_try_huge_pud(pud_t *pud, unsigned long addr, unsigned long end,
                        phys_addr_t phys_addr, pgprot_t prot,
                        unsigned int max_page_shift)
{
        if (max_page_shift < PUD_SHIFT)
                return 0;

        if (!arch_vmap_pud_supported(prot))
                return 0;

        if ((end - addr) != PUD_SIZE)
                return 0;

        if (!IS_ALIGNED(addr, PUD_SIZE))
                return 0;

        if (!IS_ALIGNED(phys_addr, PUD_SIZE))
                return 0;

        if (pud_present(*pud) && !pud_free_pmd_page(pud, addr))
                return 0;

        return pud_set_huge(pud, phys_addr, prot);
}

static int vmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
                        phys_addr_t phys_addr, pgprot_t prot,
                        unsigned int max_page_shift, pgtbl_mod_mask *mask)
{
        pud_t *pud;
        unsigned long next;

        pud = pud_alloc_track(&init_mm, p4d, addr, mask);
        if (!pud)
                return -ENOMEM;
        do {
                next = pud_addr_end(addr, end);

                if (vmap_try_huge_pud(pud, addr, next, phys_addr, prot,
                                        max_page_shift)) {
                        *mask |= PGTBL_PUD_MODIFIED;
                        continue;
                }

                if (vmap_pmd_range(pud, addr, next, phys_addr, prot,
                                        max_page_shift, mask))
                        return -ENOMEM;
        } while (pud++, phys_addr += (next - addr), addr = next, addr != end);
        return 0;
}

static int vmap_try_huge_p4d(p4d_t *p4d, unsigned long addr, unsigned long end,
                        phys_addr_t phys_addr, pgprot_t prot,
                        unsigned int max_page_shift)
{
        if (max_page_shift < P4D_SHIFT)
                return 0;

        if (!arch_vmap_p4d_supported(prot))
                return 0;

        if ((end - addr) != P4D_SIZE)
                return 0;

        if (!IS_ALIGNED(addr, P4D_SIZE))
                return 0;

        if (!IS_ALIGNED(phys_addr, P4D_SIZE))
                return 0;

        if (p4d_present(*p4d) && !p4d_free_pud_page(p4d, addr))
                return 0;

        return p4d_set_huge(p4d, phys_addr, prot);
}

static int vmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
                        phys_addr_t phys_addr, pgprot_t prot,
                        unsigned int max_page_shift, pgtbl_mod_mask *mask)
{
        p4d_t *p4d;
        unsigned long next;

        p4d = p4d_alloc_track(&init_mm, pgd, addr, mask);
        if (!p4d)
                return -ENOMEM;
        do {
                next = p4d_addr_end(addr, end);

                if (vmap_try_huge_p4d(p4d, addr, next, phys_addr, prot,
                                        max_page_shift)) {
                        *mask |= PGTBL_P4D_MODIFIED;
                        continue;
                }

                if (vmap_pud_range(p4d, addr, next, phys_addr, prot,
                                        max_page_shift, mask))
                        return -ENOMEM;
        } while (p4d++, phys_addr += (next - addr), addr = next, addr != end);
        return 0;
}

static int vmap_range_noflush(unsigned long addr, unsigned long end,
                        phys_addr_t phys_addr, pgprot_t prot,
                        unsigned int max_page_shift)
{
        pgd_t *pgd;
        unsigned long start;
        unsigned long next;
        int err;
        pgtbl_mod_mask mask = 0;

        might_sleep();
        BUG_ON(addr >= end);

        start = addr;
        pgd = pgd_offset_k(addr);
        do {
                next = pgd_addr_end(addr, end);
                err = vmap_p4d_range(pgd, addr, next, phys_addr, prot,
                                        max_page_shift, &mask);
                if (err)
                        break;
        } while (pgd++, phys_addr += (next - addr), addr = next, addr != end);

        if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
                arch_sync_kernel_mappings(start, end);

        return err;
}

int vmap_page_range(unsigned long addr, unsigned long end,
                    phys_addr_t phys_addr, pgprot_t prot)
{
        int err;

        err = vmap_range_noflush(addr, end, phys_addr, pgprot_nx(prot),
                                 ioremap_max_page_shift);
        flush_cache_vmap(addr, end);
        if (!err)
                err = kmsan_ioremap_page_range(addr, end, phys_addr, prot,
                                               ioremap_max_page_shift);
        return err;
}

int ioremap_page_range(unsigned long addr, unsigned long end,
                phys_addr_t phys_addr, pgprot_t prot)
{
        struct vm_struct *area;

        area = find_vm_area((void *)addr);
        if (!area || !(area->flags & VM_IOREMAP)) {
                WARN_ONCE(1, "vm_area at addr %lx is not marked as VM_IOREMAP\n", addr);
                return -EINVAL;
        }
        if (addr != (unsigned long)area->addr ||
            (void *)end != area->addr + get_vm_area_size(area)) {
                WARN_ONCE(1, "ioremap request [%lx,%lx) doesn't match vm_area [%lx, %lx)\n",
                          addr, end, (long)area->addr,
                          (long)area->addr + get_vm_area_size(area));
                return -ERANGE;
        }
        return vmap_page_range(addr, end, phys_addr, prot);
}

static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
                             pgtbl_mod_mask *mask)
{
        pte_t *pte;

        pte = pte_offset_kernel(pmd, addr);
        do {
                pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
                WARN_ON(!pte_none(ptent) && !pte_present(ptent));
        } while (pte++, addr += PAGE_SIZE, addr != end);
        *mask |= PGTBL_PTE_MODIFIED;
}

static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
                             pgtbl_mod_mask *mask)
{
        pmd_t *pmd;
        unsigned long next;
        int cleared;

        pmd = pmd_offset(pud, addr);
        do {
                next = pmd_addr_end(addr, end);

                cleared = pmd_clear_huge(pmd);
                if (cleared || pmd_bad(*pmd))
                        *mask |= PGTBL_PMD_MODIFIED;

                if (cleared)
                        continue;
                if (pmd_none_or_clear_bad(pmd))
                        continue;
                vunmap_pte_range(pmd, addr, next, mask);

                cond_resched();
        } while (pmd++, addr = next, addr != end);
}

static void vunmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
                             pgtbl_mod_mask *mask)
{
        pud_t *pud;
        unsigned long next;
        int cleared;

        pud = pud_offset(p4d, addr);
        do {
                next = pud_addr_end(addr, end);

                cleared = pud_clear_huge(pud);
                if (cleared || pud_bad(*pud))
                        *mask |= PGTBL_PUD_MODIFIED;

                if (cleared)
                        continue;
                if (pud_none_or_clear_bad(pud))
                        continue;
                vunmap_pmd_range(pud, addr, next, mask);
        } while (pud++, addr = next, addr != end);
}

static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
                             pgtbl_mod_mask *mask)
{
        p4d_t *p4d;
        unsigned long next;

        p4d = p4d_offset(pgd, addr);
        do {
                next = p4d_addr_end(addr, end);

                p4d_clear_huge(p4d);
                if (p4d_bad(*p4d))
                        *mask |= PGTBL_P4D_MODIFIED;

                if (p4d_none_or_clear_bad(p4d))
                        continue;
                vunmap_pud_range(p4d, addr, next, mask);
        } while (p4d++, addr = next, addr != end);
}

/*
 * vunmap_range_noflush is similar to vunmap_range, but does not
 * flush caches or TLBs.
 *
 * The caller is responsible for calling flush_cache_vmap() before calling
 * this function, and flush_tlb_kernel_range after it has returned
 * successfully (and before the addresses are expected to cause a page fault
 * or be re-mapped for something else, if TLB flushes are being delayed or
 * coalesced).
 *
 * This is an internal function only. Do not use outside mm/.
 */
void __vunmap_range_noflush(unsigned long start, unsigned long end)
{
        unsigned long next;
        pgd_t *pgd;
        unsigned long addr = start;
        pgtbl_mod_mask mask = 0;

        BUG_ON(addr >= end);
        pgd = pgd_offset_k(addr);
        do {
                next = pgd_addr_end(addr, end);
                if (pgd_bad(*pgd))
                        mask |= PGTBL_PGD_MODIFIED;
                if (pgd_none_or_clear_bad(pgd))
                        continue;
                vunmap_p4d_range(pgd, addr, next, &mask);
        } while (pgd++, addr = next, addr != end);

        if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
                arch_sync_kernel_mappings(start, end);
}

void vunmap_range_noflush(unsigned long start, unsigned long end)
{
        kmsan_vunmap_range_noflush(start, end);
        __vunmap_range_noflush(start, end);
}

/**
 * vunmap_range - unmap kernel virtual addresses
 * @addr: start of the VM area to unmap
 * @end: end of the VM area to unmap (non-inclusive)
 *
 * Clears any present PTEs in the virtual address range, flushes TLBs and
 * caches. Any subsequent access to the address before it has been re-mapped
 * is a kernel bug.
 */
void vunmap_range(unsigned long addr, unsigned long end)
{
        flush_cache_vunmap(addr, end);
        vunmap_range_noflush(addr, end);
        flush_tlb_kernel_range(addr, end);
}

static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr,
                unsigned long end, pgprot_t prot, struct page **pages, int *nr,
                pgtbl_mod_mask *mask)
{
        pte_t *pte;

        /*
         * nr is a running index into the array which helps higher level
         * callers keep track of where we're up to.
         */

        pte = pte_alloc_kernel_track(pmd, addr, mask);
        if (!pte)
                return -ENOMEM;
        do {
                struct page *page = pages[*nr];

                if (WARN_ON(!pte_none(ptep_get(pte))))
                        return -EBUSY;
                if (WARN_ON(!page))
                        return -ENOMEM;
                if (WARN_ON(!pfn_valid(page_to_pfn(page))))
                        return -EINVAL;

                set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
                (*nr)++;
        } while (pte++, addr += PAGE_SIZE, addr != end);
        *mask |= PGTBL_PTE_MODIFIED;
        return 0;
}

static int vmap_pages_pmd_range(pud_t *pud, unsigned long addr,
                unsigned long end, pgprot_t prot, struct page **pages, int *nr,
                pgtbl_mod_mask *mask)
{
        pmd_t *pmd;
        unsigned long next;

        pmd = pmd_alloc_track(&init_mm, pud, addr, mask);
        if (!pmd)
                return -ENOMEM;
        do {
                next = pmd_addr_end(addr, end);
                if (vmap_pages_pte_range(pmd, addr, next, prot, pages, nr, mask))
                        return -ENOMEM;
        } while (pmd++, addr = next, addr != end);
        return 0;
}

static int vmap_pages_pud_range(p4d_t *p4d, unsigned long addr,
                unsigned long end, pgprot_t prot, struct page **pages, int *nr,
                pgtbl_mod_mask *mask)
{
        pud_t *pud;
        unsigned long next;

        pud = pud_alloc_track(&init_mm, p4d, addr, mask);
        if (!pud)
                return -ENOMEM;
        do {
                next = pud_addr_end(addr, end);
                if (vmap_pages_pmd_range(pud, addr, next, prot, pages, nr, mask))
                        return -ENOMEM;
        } while (pud++, addr = next, addr != end);
        return 0;
}

static int vmap_pages_p4d_range(pgd_t *pgd, unsigned long addr,
                unsigned long end, pgprot_t prot, struct page **pages, int *nr,
                pgtbl_mod_mask *mask)
{
        p4d_t *p4d;
        unsigned long next;

        p4d = p4d_alloc_track(&init_mm, pgd, addr, mask);
        if (!p4d)
                return -ENOMEM;
        do {
                next = p4d_addr_end(addr, end);
                if (vmap_pages_pud_range(p4d, addr, next, prot, pages, nr, mask))
                        return -ENOMEM;
        } while (p4d++, addr = next, addr != end);
        return 0;
}

static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end,
                pgprot_t prot, struct page **pages)
{
        unsigned long start = addr;
        pgd_t *pgd;
        unsigned long next;
        int err = 0;
        int nr = 0;
        pgtbl_mod_mask mask = 0;

        BUG_ON(addr >= end);
        pgd = pgd_offset_k(addr);
        do {
                next = pgd_addr_end(addr, end);
                if (pgd_bad(*pgd))
                        mask |= PGTBL_PGD_MODIFIED;
                err = vmap_pages_p4d_range(pgd, addr, next, prot, pages, &nr, &mask);
                if (err)
                        return err;
        } while (pgd++, addr = next, addr != end);

        if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
                arch_sync_kernel_mappings(start, end);

        return 0;
}

/*
 * vmap_pages_range_noflush is similar to vmap_pages_range, but does not
 * flush caches.
 *
 * The caller is responsible for calling flush_cache_vmap() after this
 * function returns successfully and before the addresses are accessed.
 *
 * This is an internal function only. Do not use outside mm/.
 */
int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
                pgprot_t prot, struct page **pages, unsigned int page_shift)
{
        unsigned int i, nr = (end - addr) >> PAGE_SHIFT;

        WARN_ON(page_shift < PAGE_SHIFT);

        if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
                        page_shift == PAGE_SHIFT)
                return vmap_small_pages_range_noflush(addr, end, prot, pages);

        for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) {
                int err;

                err = vmap_range_noflush(addr, addr + (1UL << page_shift),
                                        page_to_phys(pages[i]), prot,
                                        page_shift);
                if (err)
                        return err;

                addr += 1UL << page_shift;
        }

        return 0;
}

int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
                pgprot_t prot, struct page **pages, unsigned int page_shift)
{
        int ret = kmsan_vmap_pages_range_noflush(addr, end, prot, pages,
                                                 page_shift);

        if (ret)
                return ret;
        return __vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
}

/**
 * vmap_pages_range - map pages to a kernel virtual address
 * @addr: start of the VM area to map
 * @end: end of the VM area to map (non-inclusive)
 * @prot: page protection flags to use
 * @pages: pages to map (always PAGE_SIZE pages)
 * @page_shift: maximum shift that the pages may be mapped with, @pages must
 * be aligned and contiguous up to at least this shift.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
static int vmap_pages_range(unsigned long addr, unsigned long end,
                pgprot_t prot, struct page **pages, unsigned int page_shift)
{
        int err;

        err = vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
        flush_cache_vmap(addr, end);
        return err;
}

static int check_sparse_vm_area(struct vm_struct *area, unsigned long start,
                                unsigned long end)
{
        might_sleep();
        if (WARN_ON_ONCE(area->flags & VM_FLUSH_RESET_PERMS))
                return -EINVAL;
        if (WARN_ON_ONCE(area->flags & VM_NO_GUARD))
                return -EINVAL;
        if (WARN_ON_ONCE(!(area->flags & VM_SPARSE)))
                return -EINVAL;
        if ((end - start) >> PAGE_SHIFT > totalram_pages())
                return -E2BIG;
        if (start < (unsigned long)area->addr ||
            (void *)end > area->addr + get_vm_area_size(area))
                return -ERANGE;
        return 0;
}

/**
 * vm_area_map_pages - map pages inside given sparse vm_area
 * @area: vm_area
 * @start: start address inside vm_area
 * @end: end address inside vm_area
 * @pages: pages to map (always PAGE_SIZE pages)
 */
int vm_area_map_pages(struct vm_struct *area, unsigned long start,
                      unsigned long end, struct page **pages)
{
        int err;

        err = check_sparse_vm_area(area, start, end);
        if (err)
                return err;

        return vmap_pages_range(start, end, PAGE_KERNEL, pages, PAGE_SHIFT);
}

/**
 * vm_area_unmap_pages - unmap pages inside given sparse vm_area
 * @area: vm_area
 * @start: start address inside vm_area
 * @end: end address inside vm_area
 */
void vm_area_unmap_pages(struct vm_struct *area, unsigned long start,
                         unsigned long end)
{
        if (check_sparse_vm_area(area, start, end))
                return;

        vunmap_range(start, end);
}

int is_vmalloc_or_module_addr(const void *x)
{
        /*
         * ARM, x86-64 and sparc64 put modules in a special place,
         * and fall back on vmalloc() if that fails. Others
         * just put it in the vmalloc space.
         */
#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
        unsigned long addr = (unsigned long)kasan_reset_tag(x);
        if (addr >= MODULES_VADDR && addr < MODULES_END)
                return 1;
#endif
        return is_vmalloc_addr(x);
}
EXPORT_SYMBOL_GPL(is_vmalloc_or_module_addr);

/*
 * Walk a vmap address to the struct page it maps. Huge vmap mappings will
 * return the tail page that corresponds to the base page address, which
 * matches small vmap mappings.
 */
struct page *vmalloc_to_page(const void *vmalloc_addr)
{
        unsigned long addr = (unsigned long) vmalloc_addr;
        struct page *page = NULL;
        pgd_t *pgd = pgd_offset_k(addr);
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *ptep, pte;

        /*
         * XXX we might need to change this if we add VIRTUAL_BUG_ON for
         * architectures that do not vmalloc module space
         */
        VIRTUAL_BUG_ON(!is_vmalloc_or_module_addr(vmalloc_addr));

        if (pgd_none(*pgd))
                return NULL;
        if (WARN_ON_ONCE(pgd_leaf(*pgd)))
                return NULL; /* XXX: no allowance for huge pgd */
        if (WARN_ON_ONCE(pgd_bad(*pgd)))
                return NULL;

        p4d = p4d_offset(pgd, addr);
        if (p4d_none(*p4d))
                return NULL;
        if (p4d_leaf(*p4d))
                return p4d_page(*p4d) + ((addr & ~P4D_MASK) >> PAGE_SHIFT);
        if (WARN_ON_ONCE(p4d_bad(*p4d)))
                return NULL;

        pud = pud_offset(p4d, addr);
        if (pud_none(*pud))
                return NULL;
        if (pud_leaf(*pud))
                return pud_page(*pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
        if (WARN_ON_ONCE(pud_bad(*pud)))
                return NULL;

        pmd = pmd_offset(pud, addr);
        if (pmd_none(*pmd))
                return NULL;
        if (pmd_leaf(*pmd))
                return pmd_page(*pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
        if (WARN_ON_ONCE(pmd_bad(*pmd)))
                return NULL;

        ptep = pte_offset_kernel(pmd, addr);
        pte = ptep_get(ptep);
        if (pte_present(pte))
                page = pte_page(pte);

        return page;
}
EXPORT_SYMBOL(vmalloc_to_page);

/*
 * Map a vmalloc()-space virtual address to the physical page frame number.
 */
unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
{
        return page_to_pfn(vmalloc_to_page(vmalloc_addr));
}
EXPORT_SYMBOL(vmalloc_to_pfn);


/*** Global kva allocator ***/

#define DEBUG_AUGMENT_PROPAGATE_CHECK 0
#define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0


static DEFINE_SPINLOCK(vmap_area_lock);
static DEFINE_SPINLOCK(free_vmap_area_lock);
/* Export for kexec only */
LIST_HEAD(vmap_area_list);
static struct rb_root vmap_area_root = RB_ROOT;
static bool vmap_initialized __read_mostly;

static struct rb_root purge_vmap_area_root = RB_ROOT;
static LIST_HEAD(purge_vmap_area_list);
static DEFINE_SPINLOCK(purge_vmap_area_lock);

/*
 * This kmem_cache is used for vmap_area objects. Instead of
 * allocating from slab we reuse an object from this cache to
 * make things faster. Especially in "no edge" splitting of
 * free block.
 */
static struct kmem_cache *vmap_area_cachep;

/*
 * This linked list is used in pair with free_vmap_area_root.
 * It gives O(1) access to prev/next to perform fast coalescing.
 */
static LIST_HEAD(free_vmap_area_list);

/*
 * This augment red-black tree represents the free vmap space.
 * All vmap_area objects in this tree are sorted by va->va_start
 * address. It is used for allocation and merging when a vmap
 * object is released.
 *
 * Each vmap_area node contains a maximum available free block
 * of its sub-tree, right or left. Therefore it is possible to
 * find a lowest match of free area.
 */
static struct rb_root free_vmap_area_root = RB_ROOT;

/*
 * Preload a CPU with one object for "no edge" split case. The
 * aim is to get rid of allocations from the atomic context, thus
 * to use more permissive allocation masks.
 */
static DEFINE_PER_CPU(struct vmap_area *, ne_fit_preload_node);

static __always_inline unsigned long
va_size(struct vmap_area *va)
{
        return (va->va_end - va->va_start);
}

static __always_inline unsigned long
get_subtree_max_size(struct rb_node *node)
{
        struct vmap_area *va;

        va = rb_entry_safe(node, struct vmap_area, rb_node);
        return va ? va->subtree_max_size : 0;
}

RB_DECLARE_CALLBACKS_MAX(static, free_vmap_area_rb_augment_cb,
        struct vmap_area, rb_node, unsigned long, subtree_max_size, va_size)

static void reclaim_and_purge_vmap_areas(void);
static BLOCKING_NOTIFIER_HEAD(vmap_notify_list);
static void drain_vmap_area_work(struct work_struct *work);
static DECLARE_WORK(drain_vmap_work, drain_vmap_area_work);

static atomic_long_t nr_vmalloc_pages;

unsigned long vmalloc_nr_pages(void)
{
        return atomic_long_read(&nr_vmalloc_pages);
}

/* Look up the first VA which satisfies addr < va_end, NULL if none. */
static struct vmap_area *find_vmap_area_exceed_addr(unsigned long addr)
{
        struct vmap_area *va = NULL;
        struct rb_node *n = vmap_area_root.rb_node;

        addr = (unsigned long)kasan_reset_tag((void *)addr);

        while (n) {
                struct vmap_area *tmp;

                tmp = rb_entry(n, struct vmap_area, rb_node);
                if (tmp->va_end > addr) {
                        va = tmp;
                        if (tmp->va_start <= addr)
                                break;

                        n = n->rb_left;
                } else
                        n = n->rb_right;
        }

        return va;
}

static struct vmap_area *__find_vmap_area(unsigned long addr, struct rb_root *root)
{
        struct rb_node *n = root->rb_node;

        addr = (unsigned long)kasan_reset_tag((void *)addr);

        while (n) {
                struct vmap_area *va;

                va = rb_entry(n, struct vmap_area, rb_node);
                if (addr < va->va_start)
                        n = n->rb_left;
                else if (addr >= va->va_end)
                        n = n->rb_right;
                else
                        return va;
        }

        return NULL;
}

/*
 * This function returns back addresses of parent node
 * and its left or right link for further processing.
 *
 * Otherwise NULL is returned. In that case all further
 * steps regarding inserting of conflicting overlap range
 * have to be declined and actually considered as a bug.
 */
static __always_inline struct rb_node **
find_va_links(struct vmap_area *va,
        struct rb_root *root, struct rb_node *from,
        struct rb_node **parent)
{
        struct vmap_area *tmp_va;
        struct rb_node **link;

        if (root) {
                link = &root->rb_node;
                if (unlikely(!*link)) {
                        *parent = NULL;
                        return link;
                }
        } else {
                link = &from;
        }

        /*
         * Go to the bottom of the tree. When we hit the last point
         * we end up with parent rb_node and correct direction, i name
         * it link, where the new va->rb_node will be attached to.
         */
        do {
                tmp_va = rb_entry(*link, struct vmap_area, rb_node);

                /*
                 * During the traversal we also do some sanity check.
                 * Trigger the BUG() if there are sides(left/right)
                 * or full overlaps.
                 */
                if (va->va_end <= tmp_va->va_start)
                        link = &(*link)->rb_left;
                else if (va->va_start >= tmp_va->va_end)
                        link = &(*link)->rb_right;
                else {
                        WARN(1, "vmalloc bug: 0x%lx-0x%lx overlaps with 0x%lx-0x%lx\n",
                                va->va_start, va->va_end, tmp_va->va_start, tmp_va->va_end);

                        return NULL;
                }
        } while (*link);

        *parent = &tmp_va->rb_node;
        return link;
}

static __always_inline struct list_head *
get_va_next_sibling(struct rb_node *parent, struct rb_node **link)
{
        struct list_head *list;

        if (unlikely(!parent))
                /*
                 * The red-black tree where we try to find VA neighbors
                 * before merging or inserting is empty, i.e. it means
                 * there is no free vmap space. Normally it does not
                 * happen but we handle this case anyway.
                 */
                return NULL;

        list = &rb_entry(parent, struct vmap_area, rb_node)->list;
        return (&parent->rb_right == link ? list->next : list);
}

static __always_inline void
__link_va(struct vmap_area *va, struct rb_root *root,
        struct rb_node *parent, struct rb_node **link,
        struct list_head *head, bool augment)
{
        /*
         * VA is still not in the list, but we can
         * identify its future previous list_head node.
         */
        if (likely(parent)) {
                head = &rb_entry(parent, struct vmap_area, rb_node)->list;
                if (&parent->rb_right != link)
                        head = head->prev;
        }

        /* Insert to the rb-tree */
        rb_link_node(&va->rb_node, parent, link);
        if (augment) {
                /*
                 * Some explanation here. Just perform simple insertion
                 * to the tree. We do not set va->subtree_max_size to
                 * its current size before calling rb_insert_augmented().
                 * It is because we populate the tree from the bottom
                 * to parent levels when the node _is_ in the tree.
                 *
                 * Therefore we set subtree_max_size to zero after insertion,
                 * to let __augment_tree_propagate_from() puts everything to
                 * the correct order later on.
                 */
                rb_insert_augmented(&va->rb_node,
                        root, &free_vmap_area_rb_augment_cb);
                va->subtree_max_size = 0;
        } else {
                rb_insert_color(&va->rb_node, root);
        }

        /* Address-sort this list */
        list_add(&va->list, head);
}

static __always_inline void
link_va(struct vmap_area *va, struct rb_root *root,
        struct rb_node *parent, struct rb_node **link,
        struct list_head *head)
{
        __link_va(va, root, parent, link, head, false);
}

static __always_inline void
link_va_augment(struct vmap_area *va, struct rb_root *root,
        struct rb_node *parent, struct rb_node **link,
        struct list_head *head)
{
        __link_va(va, root, parent, link, head, true);
}

static __always_inline void
__unlink_va(struct vmap_area *va, struct rb_root *root, bool augment)
{
        if (WARN_ON(RB_EMPTY_NODE(&va->rb_node)))
                return;

        if (augment)
                rb_erase_augmented(&va->rb_node,
                        root, &free_vmap_area_rb_augment_cb);
        else
                rb_erase(&va->rb_node, root);

        list_del_init(&va->list);
        RB_CLEAR_NODE(&va->rb_node);
}

static __always_inline void
unlink_va(struct vmap_area *va, struct rb_root *root)
{
        __unlink_va(va, root, false);
}

static __always_inline void
unlink_va_augment(struct vmap_area *va, struct rb_root *root)
{
        __unlink_va(va, root, true);
}

#if DEBUG_AUGMENT_PROPAGATE_CHECK
/*
 * Gets called when remove the node and rotate.
 */
static __always_inline unsigned long
compute_subtree_max_size(struct vmap_area *va)
{
        return max3(va_size(va),
                get_subtree_max_size(va->rb_node.rb_left),
                get_subtree_max_size(va->rb_node.rb_right));
}

static void
augment_tree_propagate_check(void)
{
        struct vmap_area *va;
        unsigned long computed_size;

        list_for_each_entry(va, &free_vmap_area_list, list) {
                computed_size = compute_subtree_max_size(va);
                if (computed_size != va->subtree_max_size)
                        pr_emerg("tree is corrupted: %lu, %lu\n",
                                va_size(va), va->subtree_max_size);
        }
}
#endif

/*
 * This function populates subtree_max_size from bottom to upper
 * levels starting from VA point. The propagation must be done
 * when VA size is modified by changing its va_start/va_end. Or
 * in case of newly inserting of VA to the tree.
 *
 * It means that __augment_tree_propagate_from() must be called:
 * - After VA has been inserted to the tree(free path);
 * - After VA has been shrunk(allocation path);
 * - After VA has been increased(merging path).
 *
 * Please note that, it does not mean that upper parent nodes
 * and their subtree_max_size are recalculated all the time up
 * to the root node.
 *
 *       4--8
 *        /\
 *       /  \
 *      /    \
 *    2--2  8--8
 *
 * For example if we modify the node 4, shrinking it to 2, then
 * no any modification is required. If we shrink the node 2 to 1
 * its subtree_max_size is updated only, and set to 1. If we shrink
 * the node 8 to 6, then its subtree_max_size is set to 6 and parent
 * node becomes 4--6.
 */
static __always_inline void
augment_tree_propagate_from(struct vmap_area *va)
{
        /*
         * Populate the tree from bottom towards the root until
         * the calculated maximum available size of checked node
         * is equal to its current one.
         */
        free_vmap_area_rb_augment_cb_propagate(&va->rb_node, NULL);

#if DEBUG_AUGMENT_PROPAGATE_CHECK
        augment_tree_propagate_check();
#endif
}

static void
insert_vmap_area(struct vmap_area *va,
        struct rb_root *root, struct list_head *head)
{
        struct rb_node **link;
        struct rb_node *parent;

        link = find_va_links(va, root, NULL, &parent);
        if (link)
                link_va(va, root, parent, link, head);
}

static void
insert_vmap_area_augment(struct vmap_area *va,
        struct rb_node *from, struct rb_root *root,
        struct list_head *head)
{
        struct rb_node **link;
        struct rb_node *parent;

        if (from)
                link = find_va_links(va, NULL, from, &parent);
        else
                link = find_va_links(va, root, NULL, &parent);

        if (link) {
                link_va_augment(va, root, parent, link, head);
                augment_tree_propagate_from(va);
        }
}

/*
 * Merge de-allocated chunk of VA memory with previous
 * and next free blocks. If coalesce is not done a new
 * free area is inserted. If VA has been merged, it is
 * freed.
 *
 * Please note, it can return NULL in case of overlap
 * ranges, followed by WARN() report. Despite it is a
 * buggy behaviour, a system can be alive and keep
 * ongoing.
 */
static __always_inline struct vmap_area *
__merge_or_add_vmap_area(struct vmap_area *va,
        struct rb_root *root, struct list_head *head, bool augment)
{
        struct vmap_area *sibling;
        struct list_head *next;
        struct rb_node **link;
        struct rb_node *parent;
        bool merged = false;

        /*
         * Find a place in the tree where VA potentially will be
         * inserted, unless it is merged with its sibling/siblings.
         */
        link = find_va_links(va, root, NULL, &parent);
        if (!link)
                return NULL;

        /*
         * Get next node of VA to check if merging can be done.
         */
        next = get_va_next_sibling(parent, link);
        if (unlikely(next == NULL))
                goto insert;

        /*
         * start            end
         * |                |
         * |<------VA------>|<-----Next----->|
         *                  |                |
         *                  start            end
         */
        if (next != head) {
                sibling = list_entry(next, struct vmap_area, list);
                if (sibling->va_start == va->va_end) {
                        sibling->va_start = va->va_start;

                        /* Free vmap_area object. */
                        kmem_cache_free(vmap_area_cachep, va);

                        /* Point to the new merged area. */
                        va = sibling;
                        merged = true;
                }
        }

        /*
         * start            end
         * |                |
         * |<-----Prev----->|<------VA------>|
         *                  |                |
         *                  start            end
         */
        if (next->prev != head) {
                sibling = list_entry(next->prev, struct vmap_area, list);
                if (sibling->va_end == va->va_start) {
                        /*
                         * If both neighbors are coalesced, it is important
                         * to unlink the "next" node first, followed by merging
                         * with "previous" one. Otherwise the tree might not be
                         * fully populated if a sibling's augmented value is
                         * "normalized" because of rotation operations.
                         */
                        if (merged)
                                __unlink_va(va, root, augment);

                        sibling->va_end = va->va_end;

                        /* Free vmap_area object. */
                        kmem_cache_free(vmap_area_cachep, va);

                        /* Point to the new merged area. */
                        va = sibling;
                        merged = true;
                }
        }

insert:
        if (!merged)
                __link_va(va, root, parent, link, head, augment);

        return va;
}

static __always_inline struct vmap_area *
merge_or_add_vmap_area(struct vmap_area *va,
        struct rb_root *root, struct list_head *head)
{
        return __merge_or_add_vmap_area(va, root, head, false);
}

static __always_inline struct vmap_area *
merge_or_add_vmap_area_augment(struct vmap_area *va,
        struct rb_root *root, struct list_head *head)
{
        va = __merge_or_add_vmap_area(va, root, head, true);
        if (va)
                augment_tree_propagate_from(va);

        return va;
}

static __always_inline bool
is_within_this_va(struct vmap_area *va, unsigned long size,
        unsigned long align, unsigned long vstart)
{
        unsigned long nva_start_addr;

        if (va->va_start > vstart)
                nva_start_addr = ALIGN(va->va_start, align);
        else
                nva_start_addr = ALIGN(vstart, align);

        /* Can be overflowed due to big size or alignment. */
        if (nva_start_addr + size < nva_start_addr ||
                        nva_start_addr < vstart)
                return false;

        return (nva_start_addr + size <= va->va_end);
}

/*
 * Find the first free block(lowest start address) in the tree,
 * that will accomplish the request corresponding to passing
 * parameters. Please note, with an alignment bigger than PAGE_SIZE,
 * a search length is adjusted to account for worst case alignment
 * overhead.
 */
static __always_inline struct vmap_area *
find_vmap_lowest_match(struct rb_root *root, unsigned long size,
        unsigned long align, unsigned long vstart, bool adjust_search_size)
{
        struct vmap_area *va;
        struct rb_node *node;
        unsigned long length;

        /* Start from the root. */
        node = root->rb_node;

        /* Adjust the search size for alignment overhead. */
        length = adjust_search_size ? size + align - 1 : size;

        while (node) {
                va = rb_entry(node, struct vmap_area, rb_node);

                if (get_subtree_max_size(node->rb_left) >= length &&
                                vstart < va->va_start) {
                        node = node->rb_left;
                } else {
                        if (is_within_this_va(va, size, align, vstart))
                                return va;

                        /*
                         * Does not make sense to go deeper towards the right
                         * sub-tree if it does not have a free block that is
                         * equal or bigger to the requested search length.
                         */
                        if (get_subtree_max_size(node->rb_right) >= length) {
                                node = node->rb_right;
                                continue;
                        }

                        /*
                         * OK. We roll back and find the first right sub-tree,
                         * that will satisfy the search criteria. It can happen
                         * due to "vstart" restriction or an alignment overhead
                         * that is bigger then PAGE_SIZE.
                         */
                        while ((node = rb_parent(node))) {
                                va = rb_entry(node, struct vmap_area, rb_node);
                                if (is_within_this_va(va, size, align, vstart))
                                        return va;

                                if (get_subtree_max_size(node->rb_right) >= length &&
                                                vstart <= va->va_start) {
                                        /*
                                         * Shift the vstart forward. Please note, we update it with
                                         * parent's start address adding "1" because we do not want
                                         * to enter same sub-tree after it has already been checked
                                         * and no suitable free block found there.
                                         */
                                        vstart = va->va_start + 1;
                                        node = node->rb_right;
                                        break;
                                }
                        }
                }
        }

        return NULL;
}

#if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
#include <linux/random.h>

static struct vmap_area *
find_vmap_lowest_linear_match(struct list_head *head, unsigned long size,
        unsigned long align, unsigned long vstart)
{
        struct vmap_area *va;

        list_for_each_entry(va, head, list) {
                if (!is_within_this_va(va, size, align, vstart))
                        continue;

                return va;
        }

        return NULL;
}

static void
find_vmap_lowest_match_check(struct rb_root *root, struct list_head *head,
                             unsigned long size, unsigned long align)
{
        struct vmap_area *va_1, *va_2;
        unsigned long vstart;
        unsigned int rnd;

        get_random_bytes(&rnd, sizeof(rnd));
        vstart = VMALLOC_START + rnd;

        va_1 = find_vmap_lowest_match(root, size, align, vstart, false);
        va_2 = find_vmap_lowest_linear_match(head, size, align, vstart);

        if (va_1 != va_2)
                pr_emerg("not lowest: t: 0x%p, l: 0x%p, v: 0x%lx\n",
                        va_1, va_2, vstart);
}
#endif

enum fit_type {
        NOTHING_FIT = 0,
        FL_FIT_TYPE = 1,        /* full fit */
        LE_FIT_TYPE = 2,        /* left edge fit */
        RE_FIT_TYPE = 3,        /* right edge fit */
        NE_FIT_TYPE = 4         /* no edge fit */
};

static __always_inline enum fit_type
classify_va_fit_type(struct vmap_area *va,
        unsigned long nva_start_addr, unsigned long size)
{
        enum fit_type type;

        /* Check if it is within VA. */
        if (nva_start_addr < va->va_start ||
                        nva_start_addr + size > va->va_end)
                return NOTHING_FIT;

        /* Now classify. */
        if (va->va_start == nva_start_addr) {
                if (va->va_end == nva_start_addr + size)
                        type = FL_FIT_TYPE;
                else
                        type = LE_FIT_TYPE;
        } else if (va->va_end == nva_start_addr + size) {
                type = RE_FIT_TYPE;
        } else {
                type = NE_FIT_TYPE;
        }

        return type;
}

static __always_inline int
adjust_va_to_fit_type(struct rb_root *root, struct list_head *head,
                      struct vmap_area *va, unsigned long nva_start_addr,
                      unsigned long size)
{
        struct vmap_area *lva = NULL;
        enum fit_type type = classify_va_fit_type(va, nva_start_addr, size);

        if (type == FL_FIT_TYPE) {
                /*
                 * No need to split VA, it fully fits.
                 *
                 * |               |
                 * V      NVA      V
                 * |---------------|
                 */
                unlink_va_augment(va, root);
                kmem_cache_free(vmap_area_cachep, va);
        } else if (type == LE_FIT_TYPE) {
                /*
                 * Split left edge of fit VA.
                 *
                 * |       |
                 * V  NVA  V   R
                 * |-------|-------|
                 */
                va->va_start += size;
        } else if (type == RE_FIT_TYPE) {
                /*
                 * Split right edge of fit VA.
                 *
                 *         |       |
                 *     L   V  NVA  V
                 * |-------|-------|
                 */
                va->va_end = nva_start_addr;
        } else if (type == NE_FIT_TYPE) {
                /*
                 * Split no edge of fit VA.
                 *
                 *     |       |
                 *   L V  NVA  V R
                 * |---|-------|---|
                 */
                lva = __this_cpu_xchg(ne_fit_preload_node, NULL);
                if (unlikely(!lva)) {
                        /*
                         * For percpu allocator we do not do any pre-allocation
                         * and leave it as it is. The reason is it most likely
                         * never ends up with NE_FIT_TYPE splitting. In case of
                         * percpu allocations offsets and sizes are aligned to
                         * fixed align request, i.e. RE_FIT_TYPE and FL_FIT_TYPE
                         * are its main fitting cases.
                         *
                         * There are a few exceptions though, as an example it is
                         * a first allocation (early boot up) when we have "one"
                         * big free space that has to be split.
                         *
                         * Also we can hit this path in case of regular "vmap"
                         * allocations, if "this" current CPU was not preloaded.
                         * See the comment in alloc_vmap_area() why. If so, then
                         * GFP_NOWAIT is used instead to get an extra object for
                         * split purpose. That is rare and most time does not
                         * occur.
                         *
                         * What happens if an allocation gets failed. Basically,
                         * an "overflow" path is triggered to purge lazily freed
                         * areas to free some memory, then, the "retry" path is
                         * triggered to repeat one more time. See more details
                         * in alloc_vmap_area() function.
                         */
                        lva = kmem_cache_alloc(vmap_area_cachep, GFP_NOWAIT);
                        if (!lva)
                                return -1;
                }

                /*
                 * Build the remainder.
                 */
                lva->va_start = va->va_start;
                lva->va_end = nva_start_addr;

                /*
                 * Shrink this VA to remaining size.
                 */
                va->va_start = nva_start_addr + size;
        } else {
                return -1;
        }

        if (type != FL_FIT_TYPE) {
                augment_tree_propagate_from(va);

                if (lva)        /* type == NE_FIT_TYPE */
                        insert_vmap_area_augment(lva, &va->rb_node, root, head);
        }

        return 0;
}

/*
 * Returns a start address of the newly allocated area, if success.
 * Otherwise a vend is returned that indicates failure.
 */
static __always_inline unsigned long
__alloc_vmap_area(struct rb_root *root, struct list_head *head,
        unsigned long size, unsigned long align,
        unsigned long vstart, unsigned long vend)
{
        bool adjust_search_size = true;
        unsigned long nva_start_addr;
        struct vmap_area *va;
        int ret;

        /*
         * Do not adjust when:
         *   a) align <= PAGE_SIZE, because it does not make any sense.
         *      All blocks(their start addresses) are at least PAGE_SIZE
         *      aligned anyway;
         *   b) a short range where a requested size corresponds to exactly
         *      specified [vstart:vend] interval and an alignment > PAGE_SIZE.
         *      With adjusted search length an allocation would not succeed.
         */
        if (align <= PAGE_SIZE || (align > PAGE_SIZE && (vend - vstart) == size))
                adjust_search_size = false;

        va = find_vmap_lowest_match(root, size, align, vstart, adjust_search_size);
        if (unlikely(!va))
                return vend;

        if (va->va_start > vstart)
                nva_start_addr = ALIGN(va->va_start, align);
        else
                nva_start_addr = ALIGN(vstart, align);

        /* Check the "vend" restriction. */
        if (nva_start_addr + size > vend)
                return vend;

        /* Update the free vmap_area. */
        ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size);
        if (WARN_ON_ONCE(ret))
                return vend;

#if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
        find_vmap_lowest_match_check(root, head, size, align);
#endif

        return nva_start_addr;
}

/*
 * Free a region of KVA allocated by alloc_vmap_area
 */
static void free_vmap_area(struct vmap_area *va)
{
        /*
         * Remove from the busy tree/list.
         */
        spin_lock(&vmap_area_lock);
        unlink_va(va, &vmap_area_root);
        spin_unlock(&vmap_area_lock);

        /*
         * Insert/Merge it back to the free tree/list.
         */
        spin_lock(&free_vmap_area_lock);
        merge_or_add_vmap_area_augment(va, &free_vmap_area_root, &free_vmap_area_list);
        spin_unlock(&free_vmap_area_lock);
}

static inline void
preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node)
{
        struct vmap_area *va = NULL;

        /*
         * Preload this CPU with one extra vmap_area object. It is used
         * when fit type of free area is NE_FIT_TYPE. It guarantees that
         * a CPU that does an allocation is preloaded.
         *
         * We do it in non-atomic context, thus it allows us to use more
         * permissive allocation masks to be more stable under low memory
         * condition and high memory pressure.
         */
        if (!this_cpu_read(ne_fit_preload_node))
                va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);

        spin_lock(lock);

        if (va && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, va))
                kmem_cache_free(vmap_area_cachep, va);
}

/*
 * Allocate a region of KVA of the specified size and alignment, within the
 * vstart and vend.
 */
static struct vmap_area *alloc_vmap_area(unsigned long size,
                                unsigned long align,
                                unsigned long vstart, unsigned long vend,
                                int node, gfp_t gfp_mask,
                                unsigned long va_flags)
{
        struct vmap_area *va;
        unsigned long freed;
        unsigned long addr;
        int purged = 0;
        int ret;

        if (unlikely(!size || offset_in_page(size) || !is_power_of_2(align)))
                return ERR_PTR(-EINVAL);

        if (unlikely(!vmap_initialized))
                return ERR_PTR(-EBUSY);

        might_sleep();
        gfp_mask = gfp_mask & GFP_RECLAIM_MASK;

        va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);
        if (unlikely(!va))
                return ERR_PTR(-ENOMEM);

        /*
         * Only scan the relevant parts containing pointers to other objects
         * to avoid false negatives.
         */
        kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask);

retry:
        preload_this_cpu_lock(&free_vmap_area_lock, gfp_mask, node);
        addr = __alloc_vmap_area(&free_vmap_area_root, &free_vmap_area_list,
                size, align, vstart, vend);
        spin_unlock(&free_vmap_area_lock);

        trace_alloc_vmap_area(addr, size, align, vstart, vend, addr == vend);

        /*
         * If an allocation fails, the "vend" address is
         * returned. Therefore trigger the overflow path.
         */
        if (unlikely(addr == vend))
                goto overflow;

        va->va_start = addr;
        va->va_end = addr + size;
        va->vm = NULL;
        va->flags = va_flags;

        spin_lock(&vmap_area_lock);
        insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
        spin_unlock(&vmap_area_lock);

        BUG_ON(!IS_ALIGNED(va->va_start, align));
        BUG_ON(va->va_start < vstart);
        BUG_ON(va->va_end > vend);

        ret = kasan_populate_vmalloc(addr, size);
        if (ret) {
                free_vmap_area(va);
                return ERR_PTR(ret);
        }

        return va;

overflow:
        if (!purged) {
                reclaim_and_purge_vmap_areas();
                purged = 1;
                goto retry;
        }

        freed = 0;
        blocking_notifier_call_chain(&vmap_notify_list, 0, &freed);

        if (freed > 0) {
                purged = 0;
                goto retry;
        }

        if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit())
                pr_warn("vmap allocation for size %lu failed: use vmalloc=<size> to increase size\n",
                        size);

        kmem_cache_free(vmap_area_cachep, va);
        return ERR_PTR(-EBUSY);
}

int register_vmap_purge_notifier(struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&vmap_notify_list, nb);
}
EXPORT_SYMBOL_GPL(register_vmap_purge_notifier);

int unregister_vmap_purge_notifier(struct notifier_block *nb)
{
        return blocking_notifier_chain_unregister(&vmap_notify_list, nb);
}
EXPORT_SYMBOL_GPL(unregister_vmap_purge_notifier);

/*
 * lazy_max_pages is the maximum amount of virtual address space we gather up
 * before attempting to purge with a TLB flush.
 *
 * There is a tradeoff here: a larger number will cover more kernel page tables
 * and take slightly longer to purge, but it will linearly reduce the number of
 * global TLB flushes that must be performed. It would seem natural to scale
 * this number up linearly with the number of CPUs (because vmapping activity
 * could also scale linearly with the number of CPUs), however it is likely
 * that in practice, workloads might be constrained in other ways that mean
 * vmap activity will not scale linearly with CPUs. Also, I want to be
 * conservative and not introduce a big latency on huge systems, so go with
 * a less aggressive log scale. It will still be an improvement over the old
 * code, and it will be simple to change the scale factor if we find that it
 * becomes a problem on bigger systems.
 */
static unsigned long lazy_max_pages(void)
{
        unsigned int log;

        log = fls(num_online_cpus());

        return log * (32UL * 1024 * 1024 / PAGE_SIZE);
}

static atomic_long_t vmap_lazy_nr = ATOMIC_LONG_INIT(0);

/*
 * Serialize vmap purging.  There is no actual critical section protected
 * by this lock, but we want to avoid concurrent calls for performance
 * reasons and to make the pcpu_get_vm_areas more deterministic.
 */
static DEFINE_MUTEX(vmap_purge_lock);

/* for per-CPU blocks */
static void purge_fragmented_blocks_allcpus(void);

/*
 * Purges all lazily-freed vmap areas.
 */
static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
{
        unsigned long resched_threshold;
        unsigned int num_purged_areas = 0;
        struct list_head local_purge_list;
        struct vmap_area *va, *n_va;

        lockdep_assert_held(&vmap_purge_lock);

        spin_lock(&purge_vmap_area_lock);
        purge_vmap_area_root = RB_ROOT;
        list_replace_init(&purge_vmap_area_list, &local_purge_list);
        spin_unlock(&purge_vmap_area_lock);

        if (unlikely(list_empty(&local_purge_list)))
                goto out;

        start = min(start,
                list_first_entry(&local_purge_list,
                        struct vmap_area, list)->va_start);

        end = max(end,
                list_last_entry(&local_purge_list,
                        struct vmap_area, list)->va_end);

        flush_tlb_kernel_range(start, end);
        resched_threshold = lazy_max_pages() << 1;

        spin_lock(&free_vmap_area_lock);
        list_for_each_entry_safe(va, n_va, &local_purge_list, list) {
                unsigned long nr = (va->va_end - va->va_start) >> PAGE_SHIFT;
                unsigned long orig_start = va->va_start;
                unsigned long orig_end = va->va_end;

                /*
                 * Finally insert or merge lazily-freed area. It is
                 * detached and there is no need to "unlink" it from
                 * anything.
                 */
                va = merge_or_add_vmap_area_augment(va, &free_vmap_area_root,
                                &free_vmap_area_list);

                if (!va)
                        continue;

                if (is_vmalloc_or_module_addr((void *)orig_start))
                        kasan_release_vmalloc(orig_start, orig_end,
                                              va->va_start, va->va_end);

                atomic_long_sub(nr, &vmap_lazy_nr);
                num_purged_areas++;

                if (atomic_long_read(&vmap_lazy_nr) < resched_threshold)
                        cond_resched_lock(&free_vmap_area_lock);
        }
        spin_unlock(&free_vmap_area_lock);

out:
        trace_purge_vmap_area_lazy(start, end, num_purged_areas);
        return num_purged_areas > 0;
}

/*
 * Reclaim vmap areas by purging fragmented blocks and purge_vmap_area_list.
 */
static void reclaim_and_purge_vmap_areas(void)

{
        mutex_lock(&vmap_purge_lock);
        purge_fragmented_blocks_allcpus();
        __purge_vmap_area_lazy(ULONG_MAX, 0);
        mutex_unlock(&vmap_purge_lock);
}

static void drain_vmap_area_work(struct work_struct *work)
{
        unsigned long nr_lazy;

        do {
                mutex_lock(&vmap_purge_lock);
                __purge_vmap_area_lazy(ULONG_MAX, 0);
                mutex_unlock(&vmap_purge_lock);

                /* Recheck if further work is required. */
                nr_lazy = atomic_long_read(&vmap_lazy_nr);
        } while (nr_lazy > lazy_max_pages());
}

/*
 * Free a vmap area, caller ensuring that the area has been unmapped,
 * unlinked and flush_cache_vunmap had been called for the correct
 * range previously.
 */
static void free_vmap_area_noflush(struct vmap_area *va)
{
        unsigned long nr_lazy_max = lazy_max_pages();
        unsigned long va_start = va->va_start;
        unsigned long nr_lazy;

        if (WARN_ON_ONCE(!list_empty(&va->list)))
                return;

        nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >>
                                PAGE_SHIFT, &vmap_lazy_nr);

        /*
         * Merge or place it to the purge tree/list.
         */
        spin_lock(&purge_vmap_area_lock);
        merge_or_add_vmap_area(va,
                &purge_vmap_area_root, &purge_vmap_area_list);
        spin_unlock(&purge_vmap_area_lock);

        trace_free_vmap_area_noflush(va_start, nr_lazy, nr_lazy_max);

        /* After this point, we may free va at any time */
        if (unlikely(nr_lazy > nr_lazy_max))
                schedule_work(&drain_vmap_work);
}

/*
 * Free and unmap a vmap area
 */
static void free_unmap_vmap_area(struct vmap_area *va)
{
        flush_cache_vunmap(va->va_start, va->va_end);
        vunmap_range_noflush(va->va_start, va->va_end);
        if (debug_pagealloc_enabled_static())
                flush_tlb_kernel_range(va->va_start, va->va_end);

        free_vmap_area_noflush(va);
}

struct vmap_area *find_vmap_area(unsigned long addr)
{
        struct vmap_area *va;

        spin_lock(&vmap_area_lock);
        va = __find_vmap_area(addr, &vmap_area_root);
        spin_unlock(&vmap_area_lock);

        return va;
}

static struct vmap_area *find_unlink_vmap_area(unsigned long addr)
{
        struct vmap_area *va;

        spin_lock(&vmap_area_lock);
        va = __find_vmap_area(addr, &vmap_area_root);
        if (va)
                unlink_va(va, &vmap_area_root);
        spin_unlock(&vmap_area_lock);

        return va;
}

/*** Per cpu kva allocator ***/

/*
 * vmap space is limited especially on 32 bit architectures. Ensure there is
 * room for at least 16 percpu vmap blocks per CPU.
 */
/*
 * If we had a constant VMALLOC_START and VMALLOC_END, we'd like to be able
 * to #define VMALLOC_SPACE             (VMALLOC_END-VMALLOC_START). Guess
 * instead (we just need a rough idea)
 */
#if BITS_PER_LONG == 32
#define VMALLOC_SPACE           (128UL*1024*1024)
#else
#define VMALLOC_SPACE           (128UL*1024*1024*1024)
#endif

#define VMALLOC_PAGES           (VMALLOC_SPACE / PAGE_SIZE)
#define VMAP_MAX_ALLOC          BITS_PER_LONG   /* 256K with 4K pages */
#define VMAP_BBMAP_BITS_MAX     1024    /* 4MB with 4K pages */
#define VMAP_BBMAP_BITS_MIN     (VMAP_MAX_ALLOC*2)
#define VMAP_MIN(x, y)          ((x) < (y) ? (x) : (y)) /* can't use min() */
#define VMAP_MAX(x, y)          ((x) > (y) ? (x) : (y)) /* can't use max() */
#define VMAP_BBMAP_BITS         \
                VMAP_MIN(VMAP_BBMAP_BITS_MAX,   \
                VMAP_MAX(VMAP_BBMAP_BITS_MIN,   \
                        VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16))

#define VMAP_BLOCK_SIZE         (VMAP_BBMAP_BITS * PAGE_SIZE)

/*
 * Purge threshold to prevent overeager purging of fragmented blocks for
 * regular operations: Purge if vb->free is less than 1/4 of the capacity.
 */
#define VMAP_PURGE_THRESHOLD    (VMAP_BBMAP_BITS / 4)

#define VMAP_RAM                0x1 /* indicates vm_map_ram area*/
#define VMAP_BLOCK              0x2 /* mark out the vmap_block sub-type*/
#define VMAP_FLAGS_MASK         0x3

struct vmap_block_queue {
        spinlock_t lock;
        struct list_head free;

        /*
         * An xarray requires an extra memory dynamically to
         * be allocated. If it is an issue, we can use rb-tree
         * instead.
         */
        struct xarray vmap_blocks;
};

struct vmap_block {
        spinlock_t lock;
        struct vmap_area *va;
        unsigned long free, dirty;
        DECLARE_BITMAP(used_map, VMAP_BBMAP_BITS);
        unsigned long dirty_min, dirty_max; /*< dirty range */
        struct list_head free_list;
        struct rcu_head rcu_head;
        struct list_head purge;
};

/* Queue of free and dirty vmap blocks, for allocation and flushing purposes */
static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);

/*
 * In order to fast access to any "vmap_block" associated with a
 * specific address, we use a hash.
 *
 * A per-cpu vmap_block_queue is used in both ways, to serialize
 * an access to free block chains among CPUs(alloc path) and it
 * also acts as a vmap_block hash(alloc/free paths). It means we
 * overload it, since we already have the per-cpu array which is
 * used as a hash table. When used as a hash a 'cpu' passed to
 * per_cpu() is not actually a CPU but rather a hash index.
 *
 * A hash function is addr_to_vb_xa() which hashes any address
 * to a specific index(in a hash) it belongs to. This then uses a
 * per_cpu() macro to access an array with generated index.
 *
 * An example:
 *
 *  CPU_1  CPU_2  CPU_0
 *    |      |      |
 *    V      V      V
 * 0     10     20     30     40     50     60
 * |------|------|------|------|------|------|...<vmap address space>
 *   CPU0   CPU1   CPU2   CPU0   CPU1   CPU2
 *
 * - CPU_1 invokes vm_unmap_ram(6), 6 belongs to CPU0 zone, thus
 *   it access: CPU0/INDEX0 -> vmap_blocks -> xa_lock;
 *
 * - CPU_2 invokes vm_unmap_ram(11), 11 belongs to CPU1 zone, thus
 *   it access: CPU1/INDEX1 -> vmap_blocks -> xa_lock;
 *
 * - CPU_0 invokes vm_unmap_ram(20), 20 belongs to CPU2 zone, thus
 *   it access: CPU2/INDEX2 -> vmap_blocks -> xa_lock.
 *
 * This technique almost always avoids lock contention on insert/remove,
 * however xarray spinlocks protect against any contention that remains.
 */
static struct xarray *
addr_to_vb_xa(unsigned long addr)
{
        int index = (addr / VMAP_BLOCK_SIZE) % num_possible_cpus();

        return &per_cpu(vmap_block_queue, index).vmap_blocks;
}

/*
 * We should probably have a fallback mechanism to allocate virtual memory
 * out of partially filled vmap blocks. However vmap block sizing should be
 * fairly reasonable according to the vmalloc size, so it shouldn't be a
 * big problem.
 */

static unsigned long addr_to_vb_idx(unsigned long addr)
{
        addr -= VMALLOC_START & ~(VMAP_BLOCK_SIZE-1);
        addr /= VMAP_BLOCK_SIZE;
        return addr;
}

static void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off)
{
        unsigned long addr;

        addr = va_start + (pages_off << PAGE_SHIFT);
        BUG_ON(addr_to_vb_idx(addr) != addr_to_vb_idx(va_start));
        return (void *)addr;
}

/**
 * new_vmap_block - allocates new vmap_block and occupies 2^order pages in this
 *                  block. Of course pages number can't exceed VMAP_BBMAP_BITS
 * @order:    how many 2^order pages should be occupied in newly allocated block
 * @gfp_mask: flags for the page level allocator
 *
 * Return: virtual address in a newly allocated block or ERR_PTR(-errno)
 */
static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
{
        struct vmap_block_queue *vbq;
        struct vmap_block *vb;
        struct vmap_area *va;
        struct xarray *xa;
        unsigned long vb_idx;
        int node, err;
        void *vaddr;

        node = numa_node_id();

        vb = kmalloc_node(sizeof(struct vmap_block),
                        gfp_mask & GFP_RECLAIM_MASK, node);
        if (unlikely(!vb))
                return ERR_PTR(-ENOMEM);

        va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
                                        VMALLOC_START, VMALLOC_END,
                                        node, gfp_mask,
                                        VMAP_RAM|VMAP_BLOCK);
        if (IS_ERR(va)) {
                kfree(vb);
                return ERR_CAST(va);
        }

        vaddr = vmap_block_vaddr(va->va_start, 0);
        spin_lock_init(&vb->lock);
        vb->va = va;
        /* At least something should be left free */
        BUG_ON(VMAP_BBMAP_BITS <= (1UL << order));
        bitmap_zero(vb->used_map, VMAP_BBMAP_BITS);
        vb->free = VMAP_BBMAP_BITS - (1UL << order);
        vb->dirty = 0;
        vb->dirty_min = VMAP_BBMAP_BITS;
        vb->dirty_max = 0;
        bitmap_set(vb->used_map, 0, (1UL << order));
        INIT_LIST_HEAD(&vb->free_list);

        xa = addr_to_vb_xa(va->va_start);
        vb_idx = addr_to_vb_idx(va->va_start);
        err = xa_insert(xa, vb_idx, vb, gfp_mask);
        if (err) {
                kfree(vb);
                free_vmap_area(va);
                return ERR_PTR(err);
        }

        vbq = raw_cpu_ptr(&vmap_block_queue);
        spin_lock(&vbq->lock);
        list_add_tail_rcu(&vb->free_list, &vbq->free);
        spin_unlock(&vbq->lock);

        return vaddr;
}

static void free_vmap_block(struct vmap_block *vb)
{
        struct vmap_block *tmp;
        struct xarray *xa;

        xa = addr_to_vb_xa(vb->va->va_start);
        tmp = xa_erase(xa, addr_to_vb_idx(vb->va->va_start));
        BUG_ON(tmp != vb);

        spin_lock(&vmap_area_lock);
        unlink_va(vb->va, &vmap_area_root);
        spin_unlock(&vmap_area_lock);

        free_vmap_area_noflush(vb->va);
        kfree_rcu(vb, rcu_head);
}

static bool purge_fragmented_block(struct vmap_block *vb,
                struct vmap_block_queue *vbq, struct list_head *purge_list,
                bool force_purge)
{
        if (vb->free + vb->dirty != VMAP_BBMAP_BITS ||
            vb->dirty == VMAP_BBMAP_BITS)
                return false;

        /* Don't overeagerly purge usable blocks unless requested */
        if (!(force_purge || vb->free < VMAP_PURGE_THRESHOLD))
                return false;

        /* prevent further allocs after releasing lock */
        WRITE_ONCE(vb->free, 0);
        /* prevent purging it again */
        WRITE_ONCE(vb->dirty, VMAP_BBMAP_BITS);
        vb->dirty_min = 0;
        vb->dirty_max = VMAP_BBMAP_BITS;
        spin_lock(&vbq->lock);
        list_del_rcu(&vb->free_list);
        spin_unlock(&vbq->lock);
        list_add_tail(&vb->purge, purge_list);
        return true;
}

static void free_purged_blocks(struct list_head *purge_list)
{
        struct vmap_block *vb, *n_vb;

        list_for_each_entry_safe(vb, n_vb, purge_list, purge) {
                list_del(&vb->purge);
                free_vmap_block(vb);
        }
}

static void purge_fragmented_blocks(int cpu)
{
        LIST_HEAD(purge);
        struct vmap_block *vb;
        struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);

        rcu_read_lock();
        list_for_each_entry_rcu(vb, &vbq->free, free_list) {
                unsigned long free = READ_ONCE(vb->free);
                unsigned long dirty = READ_ONCE(vb->dirty);

                if (free + dirty != VMAP_BBMAP_BITS ||
                    dirty == VMAP_BBMAP_BITS)
                        continue;

                spin_lock(&vb->lock);
                purge_fragmented_block(vb, vbq, &purge, true);
                spin_unlock(&vb->lock);
        }
        rcu_read_unlock();
        free_purged_blocks(&purge);
}

static void purge_fragmented_blocks_allcpus(void)
{
        int cpu;

        for_each_possible_cpu(cpu)
                purge_fragmented_blocks(cpu);
}

static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
{
        struct vmap_block_queue *vbq;
        struct vmap_block *vb;
        void *vaddr = NULL;
        unsigned int order;

        BUG_ON(offset_in_page(size));
        BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
        if (WARN_ON(size == 0)) {
                /*
                 * Allocating 0 bytes isn't what caller wants since
                 * get_order(0) returns funny result. Just warn and terminate
                 * early.
                 */
                return NULL;
        }
        order = get_order(size);

        rcu_read_lock();
        vbq = raw_cpu_ptr(&vmap_block_queue);
        list_for_each_entry_rcu(vb, &vbq->free, free_list) {
                unsigned long pages_off;

                if (READ_ONCE(vb->free) < (1UL << order))
                        continue;

                spin_lock(&vb->lock);
                if (vb->free < (1UL << order)) {
                        spin_unlock(&vb->lock);
                        continue;
                }

                pages_off = VMAP_BBMAP_BITS - vb->free;
                vaddr = vmap_block_vaddr(vb->va->va_start, pages_off);
                WRITE_ONCE(vb->free, vb->free - (1UL << order));
                bitmap_set(vb->used_map, pages_off, (1UL << order));
                if (vb->free == 0) {
                        spin_lock(&vbq->lock);
                        list_del_rcu(&vb->free_list);
                        spin_unlock(&vbq->lock);
                }

                spin_unlock(&vb->lock);
                break;
        }

        rcu_read_unlock();

        /* Allocate new block if nothing was found */
        if (!vaddr)
                vaddr = new_vmap_block(order, gfp_mask);

        return vaddr;
}

static void vb_free(unsigned long addr, unsigned long size)
{
        unsigned long offset;
        unsigned int order;
        struct vmap_block *vb;
        struct xarray *xa;

        BUG_ON(offset_in_page(size));
        BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);

        flush_cache_vunmap(addr, addr + size);

        order = get_order(size);
        offset = (addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT;

        xa = addr_to_vb_xa(addr);
        vb = xa_load(xa, addr_to_vb_idx(addr));

        spin_lock(&vb->lock);
        bitmap_clear(vb->used_map, offset, (1UL << order));
        spin_unlock(&vb->lock);

        vunmap_range_noflush(addr, addr + size);

        if (debug_pagealloc_enabled_static())
                flush_tlb_kernel_range(addr, addr + size);

        spin_lock(&vb->lock);

        /* Expand the not yet TLB flushed dirty range */
        vb->dirty_min = min(vb->dirty_min, offset);
        vb->dirty_max = max(vb->dirty_max, offset + (1UL << order));

        WRITE_ONCE(vb->dirty, vb->dirty + (1UL << order));
        if (vb->dirty == VMAP_BBMAP_BITS) {
                BUG_ON(vb->free);
                spin_unlock(&vb->lock);
                free_vmap_block(vb);
        } else
                spin_unlock(&vb->lock);
}

static void _vm_unmap_aliases(unsigned long start, unsigned long end, int flush)
{
        LIST_HEAD(purge_list);
        int cpu;

        if (unlikely(!vmap_initialized))
                return;

        mutex_lock(&vmap_purge_lock);

        for_each_possible_cpu(cpu) {
                struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
                struct vmap_block *vb;
                unsigned long idx;

                rcu_read_lock();
                xa_for_each(&vbq->vmap_blocks, idx, vb) {
                        spin_lock(&vb->lock);

                        /*
                         * Try to purge a fragmented block first. If it's
                         * not purgeable, check whether there is dirty
                         * space to be flushed.
                         */
                        if (!purge_fragmented_block(vb, vbq, &purge_list, false) &&
                            vb->dirty_max && vb->dirty != VMAP_BBMAP_BITS) {
                                unsigned long va_start = vb->va->va_start;
                                unsigned long s, e;

                                s = va_start + (vb->dirty_min << PAGE_SHIFT);
                                e = va_start + (vb->dirty_max << PAGE_SHIFT);

                                start = min(s, start);
                                end   = max(e, end);

                                /* Prevent that this is flushed again */
                                vb->dirty_min = VMAP_BBMAP_BITS;
                                vb->dirty_max = 0;

                                flush = 1;
                        }
                        spin_unlock(&vb->lock);
                }
                rcu_read_unlock();
        }
        free_purged_blocks(&purge_list);

        if (!__purge_vmap_area_lazy(start, end) && flush)
                flush_tlb_kernel_range(start, end);
        mutex_unlock(&vmap_purge_lock);
}

/**
 * vm_unmap_aliases - unmap outstanding lazy aliases in the vmap layer
 *
 * The vmap/vmalloc layer lazily flushes kernel virtual mappings primarily
 * to amortize TLB flushing overheads. What this means is that any page you
 * have now, may, in a former life, have been mapped into kernel virtual
 * address by the vmap layer and so there might be some CPUs with TLB entries
 * still referencing that page (additional to the regular 1:1 kernel mapping).
 *
 * vm_unmap_aliases flushes all such lazy mappings. After it returns, we can
 * be sure that none of the pages we have control over will have any aliases
 * from the vmap layer.
 */
void vm_unmap_aliases(void)
{
        unsigned long start = ULONG_MAX, end = 0;
        int flush = 0;

        _vm_unmap_aliases(start, end, flush);
}
EXPORT_SYMBOL_GPL(vm_unmap_aliases);

/**
 * vm_unmap_ram - unmap linear kernel address space set up by vm_map_ram
 * @mem: the pointer returned by vm_map_ram
 * @count: the count passed to that vm_map_ram call (cannot unmap partial)
 */
void vm_unmap_ram(const void *mem, unsigned int count)
{
        unsigned long size = (unsigned long)count << PAGE_SHIFT;
        unsigned long addr = (unsigned long)kasan_reset_tag(mem);
        struct vmap_area *va;

        might_sleep();
        BUG_ON(!addr);
        BUG_ON(addr < VMALLOC_START);
        BUG_ON(addr > VMALLOC_END);
        BUG_ON(!PAGE_ALIGNED(addr));

        kasan_poison_vmalloc(mem, size);

        if (likely(count <= VMAP_MAX_ALLOC)) {
                debug_check_no_locks_freed(mem, size);
                vb_free(addr, size);
                return;
        }

        va = find_unlink_vmap_area(addr);
        if (WARN_ON_ONCE(!va))
                return;

        debug_check_no_locks_freed((void *)va->va_start,
                                    (va->va_end - va->va_start));
        free_unmap_vmap_area(va);
}
EXPORT_SYMBOL(vm_unmap_ram);

/**
 * vm_map_ram - map pages linearly into kernel virtual address (vmalloc space)
 * @pages: an array of pointers to the pages to be mapped
 * @count: number of pages
 * @node: prefer to allocate data structures on this node
 *
 * If you use this function for less than VMAP_MAX_ALLOC pages, it could be
 * faster than vmap so it's good.  But if you mix long-life and short-life
 * objects with vm_map_ram(), it could consume lots of address space through
 * fragmentation (especially on a 32bit machine).  You could see failures in
 * the end.  Please use this function for short-lived objects.
 *
 * Returns: a pointer to the address that has been mapped, or %NULL on failure
 */
void *vm_map_ram(struct page **pages, unsigned int count, int node)
{
        unsigned long size = (unsigned long)count << PAGE_SHIFT;
        unsigned long addr;
        void *mem;

        if (likely(count <= VMAP_MAX_ALLOC)) {
                mem = vb_alloc(size, GFP_KERNEL);
                if (IS_ERR(mem))
                        return NULL;
                addr = (unsigned long)mem;
        } else {
                struct vmap_area *va;
                va = alloc_vmap_area(size, PAGE_SIZE,
                                VMALLOC_START, VMALLOC_END,
                                node, GFP_KERNEL, VMAP_RAM);
                if (IS_ERR(va))
                        return NULL;

                addr = va->va_start;
                mem = (void *)addr;
        }

        if (vmap_pages_range(addr, addr + size, PAGE_KERNEL,
                                pages, PAGE_SHIFT) < 0) {
                vm_unmap_ram(mem, count);
                return NULL;
        }

        /*
         * Mark the pages as accessible, now that they are mapped.
         * With hardware tag-based KASAN, marking is skipped for
         * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc().
         */
        mem = kasan_unpoison_vmalloc(mem, size, KASAN_VMALLOC_PROT_NORMAL);

        return mem;
}
EXPORT_SYMBOL(vm_map_ram);

static struct vm_struct *vmlist __initdata;

static inline unsigned int vm_area_page_order(struct vm_struct *vm)
{
#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
        return vm->page_order;
#else
        return 0;
#endif
}

static inline void set_vm_area_page_order(struct vm_struct *vm, unsigned int order)
{
#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
        vm->page_order = order;
#else
        BUG_ON(order != 0);
#endif
}

/**
 * vm_area_add_early - add vmap area early during boot
 * @vm: vm_struct to add
 *
 * This function is used to add fixed kernel vm area to vmlist before
 * vmalloc_init() is called.  @vm->addr, @vm->size, and @vm->flags
 * should contain proper values and the other fields should be zero.
 *
 * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
 */
void __init vm_area_add_early(struct vm_struct *vm)
{
        struct vm_struct *tmp, **p;

        BUG_ON(vmap_initialized);
        for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
                if (tmp->addr >= vm->addr) {
                        BUG_ON(tmp->addr < vm->addr + vm->size);
                        break;
                } else
                        BUG_ON(tmp->addr + tmp->size > vm->addr);
        }
        vm->next = *p;
        *p = vm;
}

/**
 * vm_area_register_early - register vmap area early during boot
 * @vm: vm_struct to register
 * @align: requested alignment
 *
 * This function is used to register kernel vm area before
 * vmalloc_init() is called.  @vm->size and @vm->flags should contain
 * proper values on entry and other fields should be zero.  On return,
 * vm->addr contains the allocated address.
 *
 * DO NOT USE THIS FUNCTION UNLESS YOU KNOW WHAT YOU'RE DOING.
 */
void __init vm_area_register_early(struct vm_struct *vm, size_t align)
{
        unsigned long addr = ALIGN(VMALLOC_START, align);
        struct vm_struct *cur, **p;

        BUG_ON(vmap_initialized);

        for (p = &vmlist; (cur = *p) != NULL; p = &cur->next) {
                if ((unsigned long)cur->addr - addr >= vm->size)
                        break;
                addr = ALIGN((unsigned long)cur->addr + cur->size, align);
        }

        BUG_ON(addr > VMALLOC_END - vm->size);
        vm->addr = (void *)addr;
        vm->next = *p;
        *p = vm;
        kasan_populate_early_vm_area_shadow(vm->addr, vm->size);
}

static void vmap_init_free_space(void)
{
        unsigned long vmap_start = 1;
        const unsigned long vmap_end = ULONG_MAX;
        struct vmap_area *busy, *free;

        /*
         *     B     F     B     B     B     F
         * -|-----|.....|-----|-----|-----|.....|-
         *  |           The KVA space           |
         *  |<--------------------------------->|
         */
        list_for_each_entry(busy, &vmap_area_list, list) {
                if (busy->va_start - vmap_start > 0) {
                        free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
                        if (!WARN_ON_ONCE(!free)) {
                                free->va_start = vmap_start;
                                free->va_end = busy->va_start;

                                insert_vmap_area_augment(free, NULL,
                                        &free_vmap_area_root,
                                                &free_vmap_area_list);
                        }
                }

                vmap_start = busy->va_end;
        }

        if (vmap_end - vmap_start > 0) {
                free = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
                if (!WARN_ON_ONCE(!free)) {
                        free->va_start = vmap_start;
                        free->va_end = vmap_end;

                        insert_vmap_area_augment(free, NULL,
                                &free_vmap_area_root,
                                        &free_vmap_area_list);
                }
        }
}

static inline void setup_vmalloc_vm_locked(struct vm_struct *vm,
        struct vmap_area *va, unsigned long flags, const void *caller)
{
        vm->flags = flags;
        vm->addr = (void *)va->va_start;
        vm->size = va->va_end - va->va_start;
        vm->caller = caller;
        va->vm = vm;
}

static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
                              unsigned long flags, const void *caller)
{
        spin_lock(&vmap_area_lock);
        setup_vmalloc_vm_locked(vm, va, flags, caller);
        spin_unlock(&vmap_area_lock);
}

static void clear_vm_uninitialized_flag(struct vm_struct *vm)
{
        /*
         * Before removing VM_UNINITIALIZED,
         * we should make sure that vm has proper values.
         * Pair with smp_rmb() in show_numa_info().
         */
        smp_wmb();
        vm->flags &= ~VM_UNINITIALIZED;
}

static struct vm_struct *__get_vm_area_node(unsigned long size,
                unsigned long align, unsigned long shift, unsigned long flags,
                unsigned long start, unsigned long end, int node,
                gfp_t gfp_mask, const void *caller)
{
        struct vmap_area *va;
        struct vm_struct *area;
        unsigned long requested_size = size;

        BUG_ON(in_interrupt());
        size = ALIGN(size, 1ul << shift);
        if (unlikely(!size))
                return NULL;

        if (flags & VM_IOREMAP)
                align = 1ul << clamp_t(int, get_count_order_long(size),
                                       PAGE_SHIFT, IOREMAP_MAX_ORDER);

        area = kzalloc_node(sizeof(*area), gfp_mask & GFP_RECLAIM_MASK, node);
        if (unlikely(!area))
                return NULL;

        if (!(flags & VM_NO_GUARD))
                size += PAGE_SIZE;

        va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0);
        if (IS_ERR(va)) {
                kfree(area);
                return NULL;
        }

        setup_vmalloc_vm(area, va, flags, caller);

        /*
         * Mark pages for non-VM_ALLOC mappings as accessible. Do it now as a
         * best-effort approach, as they can be mapped outside of vmalloc code.
         * For VM_ALLOC mappings, the pages are marked as accessible after
         * getting mapped in __vmalloc_node_range().
         * With hardware tag-based KASAN, marking is skipped for
         * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc().
         */
        if (!(flags & VM_ALLOC))
                area->addr = kasan_unpoison_vmalloc(area->addr, requested_size,
                                                    KASAN_VMALLOC_PROT_NORMAL);

        return area;
}

struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
                                       unsigned long start, unsigned long end,
                                       const void *caller)
{
        return __get_vm_area_node(size, 1, PAGE_SHIFT, flags, start, end,
                                  NUMA_NO_NODE, GFP_KERNEL, caller);
}

/**
 * get_vm_area - reserve a contiguous kernel virtual area
 * @size:        size of the area
 * @flags:       %VM_IOREMAP for I/O mappings or VM_ALLOC
 *
 * Search an area of @size in the kernel virtual mapping area,
 * and reserved it for out purposes.  Returns the area descriptor
 * on success or %NULL on failure.
 *
 * Return: the area descriptor on success or %NULL on failure.
 */
struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
{
        return __get_vm_area_node(size, 1, PAGE_SHIFT, flags,
                                  VMALLOC_START, VMALLOC_END,
                                  NUMA_NO_NODE, GFP_KERNEL,
                                  __builtin_return_address(0));
}

struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
                                const void *caller)
{
        return __get_vm_area_node(size, 1, PAGE_SHIFT, flags,
                                  VMALLOC_START, VMALLOC_END,
                                  NUMA_NO_NODE, GFP_KERNEL, caller);
}

/**
 * find_vm_area - find a continuous kernel virtual area
 * @addr:         base address
 *
 * Search for the kernel VM area starting at @addr, and return it.
 * It is up to the caller to do all required locking to keep the returned
 * pointer valid.
 *
 * Return: the area descriptor on success or %NULL on failure.
 */
struct vm_struct *find_vm_area(const void *addr)
{
        struct vmap_area *va;

        va = find_vmap_area((unsigned long)addr);
        if (!va)
                return NULL;

        return va->vm;
}

/**
 * remove_vm_area - find and remove a continuous kernel virtual area
 * @addr:           base address
 *
 * Search for the kernel VM area starting at @addr, and remove it.
 * This function returns the found VM area, but using it is NOT safe
 * on SMP machines, except for its size or flags.
 *
 * Return: the area descriptor on success or %NULL on failure.
 */
struct vm_struct *remove_vm_area(const void *addr)
{
        struct vmap_area *va;
        struct vm_struct *vm;

        might_sleep();

        if (WARN(!PAGE_ALIGNED(addr), "Trying to vfree() bad address (%p)\n",
                        addr))
                return NULL;

        va = find_unlink_vmap_area((unsigned long)addr);
        if (!va || !va->vm)
                return NULL;
        vm = va->vm;

        debug_check_no_locks_freed(vm->addr, get_vm_area_size(vm));
        debug_check_no_obj_freed(vm->addr, get_vm_area_size(vm));
        kasan_free_module_shadow(vm);
        kasan_poison_vmalloc(vm->addr, get_vm_area_size(vm));

        free_unmap_vmap_area(va);
        return vm;
}

static inline void set_area_direct_map(const struct vm_struct *area,
                                       int (*set_direct_map)(struct page *page))
{
        int i;

        /* HUGE_VMALLOC passes small pages to set_direct_map */
        for (i = 0; i < area->nr_pages; i++)
                if (page_address(area->pages[i]))
                        set_direct_map(area->pages[i]);
}

/*
 * Flush the vm mapping and reset the direct map.
 */
static void vm_reset_perms(struct vm_struct *area)
{
        unsigned long start = ULONG_MAX, end = 0;
        unsigned int page_order = vm_area_page_order(area);
        int flush_dmap = 0;
        int i;

        /*
         * Find the start and end range of the direct mappings to make sure that
         * the vm_unmap_aliases() flush includes the direct map.
         */
        for (i = 0; i < area->nr_pages; i += 1U << page_order) {
                unsigned long addr = (unsigned long)page_address(area->pages[i]);

                if (addr) {
                        unsigned long page_size;

                        page_size = PAGE_SIZE << page_order;
                        start = min(addr, start);
                        end = max(addr + page_size, end);
                        flush_dmap = 1;
                }
        }

        /*
         * Set direct map to something invalid so that it won't be cached if
         * there are any accesses after the TLB flush, then flush the TLB and
         * reset the direct map permissions to the default.
         */
        set_area_direct_map(area, set_direct_map_invalid_noflush);
        _vm_unmap_aliases(start, end, flush_dmap);
        set_area_direct_map(area, set_direct_map_default_noflush);
}

static void delayed_vfree_work(struct work_struct *w)
{
        struct vfree_deferred *p = container_of(w, struct vfree_deferred, wq);
        struct llist_node *t, *llnode;

        llist_for_each_safe(llnode, t, llist_del_all(&p->list))
                vfree(llnode);
}

/**
 * vfree_atomic - release memory allocated by vmalloc()
 * @addr:         memory base address
 *
 * This one is just like vfree() but can be called in any atomic context
 * except NMIs.
 */
void vfree_atomic(const void *addr)
{
        struct vfree_deferred *p = raw_cpu_ptr(&vfree_deferred);

        BUG_ON(in_nmi());
        kmemleak_free(addr);

        /*
         * Use raw_cpu_ptr() because this can be called from preemptible
         * context. Preemption is absolutely fine here, because the llist_add()
         * implementation is lockless, so it works even if we are adding to
         * another cpu's list. schedule_work() should be fine with this too.
         */
        if (addr && llist_add((struct llist_node *)addr, &p->list))
                schedule_work(&p->wq);
}

/**
 * vfree - Release memory allocated by vmalloc()
 * @addr:  Memory base address
 *
 * Free the virtually continuous memory area starting at @addr, as obtained
 * from one of the vmalloc() family of APIs.  This will usually also free the
 * physical memory underlying the virtual allocation, but that memory is
 * reference counted, so it will not be freed until the last user goes away.
 *
 * If @addr is NULL, no operation is performed.
 *
 * Context:
 * May sleep if called *not* from interrupt context.
 * Must not be called in NMI context (strictly speaking, it could be
 * if we have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, but making the calling
 * conventions for vfree() arch-dependent would be a really bad idea).
 */
void vfree(const void *addr)
{
        struct vm_struct *vm;
        int i;

        if (unlikely(in_interrupt())) {
                vfree_atomic(addr);
                return;
        }

        BUG_ON(in_nmi());
        kmemleak_free(addr);
        might_sleep();

        if (!addr)
                return;

        vm = remove_vm_area(addr);
        if (unlikely(!vm)) {
                WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
                                addr);
                return;
        }

        if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS))
                vm_reset_perms(vm);
        for (i = 0; i < vm->nr_pages; i++) {
                struct page *page = vm->pages[i];

                BUG_ON(!page);
                mod_memcg_page_state(page, MEMCG_VMALLOC, -1);
                /*
                 * High-order allocs for huge vmallocs are split, so
                 * can be freed as an array of order-0 allocations
                 */
                __free_page(page);
                cond_resched();
        }
        atomic_long_sub(vm->nr_pages, &nr_vmalloc_pages);
        kvfree(vm->pages);
        kfree(vm);
}
EXPORT_SYMBOL(vfree);

/**
 * vunmap - release virtual mapping obtained by vmap()
 * @addr:   memory base address
 *
 * Free the virtually contiguous memory area starting at @addr,
 * which was created from the page array passed to vmap().
 *
 * Must not be called in interrupt context.
 */
void vunmap(const void *addr)
{
        struct vm_struct *vm;

        BUG_ON(in_interrupt());
        might_sleep();

        if (!addr)
                return;
        vm = remove_vm_area(addr);
        if (unlikely(!vm)) {
                WARN(1, KERN_ERR "Trying to vunmap() nonexistent vm area (%p)\n",
                                addr);
                return;
        }
        kfree(vm);
}
EXPORT_SYMBOL(vunmap);

/**
 * vmap - map an array of pages into virtually contiguous space
 * @pages: array of page pointers
 * @count: number of pages to map
 * @flags: vm_area->flags
 * @prot: page protection for the mapping
 *
 * Maps @count pages from @pages into contiguous kernel virtual space.
 * If @flags contains %VM_MAP_PUT_PAGES the ownership of the pages array itself
 * (which must be kmalloc or vmalloc memory) and one reference per pages in it
 * are transferred from the caller to vmap(), and will be freed / dropped when
 * vfree() is called on the return value.
 *
 * Return: the address of the area or %NULL on failure
 */
void *vmap(struct page **pages, unsigned int count,
           unsigned long flags, pgprot_t prot)
{
        struct vm_struct *area;
        unsigned long addr;
        unsigned long size;             /* In bytes */

        might_sleep();

        if (WARN_ON_ONCE(flags & VM_FLUSH_RESET_PERMS))
                return NULL;

        /*
         * Your top guard is someone else's bottom guard. Not having a top
         * guard compromises someone else's mappings too.
         */
        if (WARN_ON_ONCE(flags & VM_NO_GUARD))
                flags &= ~VM_NO_GUARD;

        if (count > totalram_pages())
                return NULL;

        size = (unsigned long)count << PAGE_SHIFT;
        area = get_vm_area_caller(size, flags, __builtin_return_address(0));
        if (!area)
                return NULL;

        addr = (unsigned long)area->addr;
        if (vmap_pages_range(addr, addr + size, pgprot_nx(prot),
                                pages, PAGE_SHIFT) < 0) {
                vunmap(area->addr);
                return NULL;
        }

        if (flags & VM_MAP_PUT_PAGES) {
                area->pages = pages;
                area->nr_pages = count;
        }
        return area->addr;
}
EXPORT_SYMBOL(vmap);

#ifdef CONFIG_VMAP_PFN
struct vmap_pfn_data {
        unsigned long   *pfns;
        pgprot_t        prot;
        unsigned int    idx;
};

static int vmap_pfn_apply(pte_t *pte, unsigned long addr, void *private)
{
        struct vmap_pfn_data *data = private;
        unsigned long pfn = data->pfns[data->idx];
        pte_t ptent;

        if (WARN_ON_ONCE(pfn_valid(pfn)))
                return -EINVAL;

        ptent = pte_mkspecial(pfn_pte(pfn, data->prot));
        set_pte_at(&init_mm, addr, pte, ptent);

        data->idx++;
        return 0;
}

/**
 * vmap_pfn - map an array of PFNs into virtually contiguous space
 * @pfns: array of PFNs
 * @count: number of pages to map
 * @prot: page protection for the mapping
 *
 * Maps @count PFNs from @pfns into contiguous kernel virtual space and returns
 * the start address of the mapping.
 */
void *vmap_pfn(unsigned long *pfns, unsigned int count, pgprot_t prot)
{
        struct vmap_pfn_data data = { .pfns = pfns, .prot = pgprot_nx(prot) };
        struct vm_struct *area;

        area = get_vm_area_caller(count * PAGE_SIZE, VM_IOREMAP,
                        __builtin_return_address(0));
        if (!area)
                return NULL;
        if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
                        count * PAGE_SIZE, vmap_pfn_apply, &data)) {
                free_vm_area(area);
                return NULL;
        }

        flush_cache_vmap((unsigned long)area->addr,
                         (unsigned long)area->addr + count * PAGE_SIZE);

        return area->addr;
}
EXPORT_SYMBOL_GPL(vmap_pfn);
#endif /* CONFIG_VMAP_PFN */

static inline unsigned int
vm_area_alloc_pages(gfp_t gfp, int nid,
                unsigned int order, unsigned int nr_pages, struct page **pages)
{
        unsigned int nr_allocated = 0;
        gfp_t alloc_gfp = gfp;
        bool nofail = false;
        struct page *page;
        int i;

        /*
         * For order-0 pages we make use of bulk allocator, if
         * the page array is partly or not at all populated due
         * to fails, fallback to a single page allocator that is
         * more permissive.
         */
        if (!order) {
                /* bulk allocator doesn't support nofail req. officially */
                gfp_t bulk_gfp = gfp & ~__GFP_NOFAIL;

                while (nr_allocated < nr_pages) {
                        unsigned int nr, nr_pages_request;

                        /*
                         * A maximum allowed request is hard-coded and is 100
                         * pages per call. That is done in order to prevent a
                         * long preemption off scenario in the bulk-allocator
                         * so the range is [1:100].
                         */
                        nr_pages_request = min(100U, nr_pages - nr_allocated);

                        /* memory allocation should consider mempolicy, we can't
                         * wrongly use nearest node when nid == NUMA_NO_NODE,
                         * otherwise memory may be allocated in only one node,
                         * but mempolicy wants to alloc memory by interleaving.
                         */
                        if (IS_ENABLED(CONFIG_NUMA) && nid == NUMA_NO_NODE)
                                nr = alloc_pages_bulk_array_mempolicy(bulk_gfp,
                                                        nr_pages_request,
                                                        pages + nr_allocated);

                        else
                                nr = alloc_pages_bulk_array_node(bulk_gfp, nid,
                                                        nr_pages_request,
                                                        pages + nr_allocated);

                        nr_allocated += nr;
                        cond_resched();

                        /*
                         * If zero or pages were obtained partly,
                         * fallback to a single page allocator.
                         */
                        if (nr != nr_pages_request)
                                break;
                }
        } else if (gfp & __GFP_NOFAIL) {
                /*
                 * Higher order nofail allocations are really expensive and
                 * potentially dangerous (pre-mature OOM, disruptive reclaim
                 * and compaction etc.
                 */
                alloc_gfp &= ~__GFP_NOFAIL;
                nofail = true;
        }

        /* High-order pages or fallback path if "bulk" fails. */
        while (nr_allocated < nr_pages) {
                if (fatal_signal_pending(current))
                        break;

                if (nid == NUMA_NO_NODE)
                        page = alloc_pages(alloc_gfp, order);
                else
                        page = alloc_pages_node(nid, alloc_gfp, order);
                if (unlikely(!page)) {
                        if (!nofail)
                                break;

                        /* fall back to the zero order allocations */
                        alloc_gfp |= __GFP_NOFAIL;
                        order = 0;
                        continue;
                }

                /*
                 * Higher order allocations must be able to be treated as
                 * indepdenent small pages by callers (as they can with
                 * small-page vmallocs). Some drivers do their own refcounting
                 * on vmalloc_to_page() pages, some use page->mapping,
                 * page->lru, etc.
                 */
                if (order)
                        split_page(page, order);

                /*
                 * Careful, we allocate and map page-order pages, but
                 * tracking is done per PAGE_SIZE page so as to keep the
                 * vm_struct APIs independent of the physical/mapped size.
                 */
                for (i = 0; i < (1U << order); i++)
                        pages[nr_allocated + i] = page + i;

                cond_resched();
                nr_allocated += 1U << order;
        }

        return nr_allocated;
}

static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
                                 pgprot_t prot, unsigned int page_shift,
                                 int node)
{
        const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
        bool nofail = gfp_mask & __GFP_NOFAIL;
        unsigned long addr = (unsigned long)area->addr;
        unsigned long size = get_vm_area_size(area);
        unsigned long array_size;
        unsigned int nr_small_pages = size >> PAGE_SHIFT;
        unsigned int page_order;
        unsigned int flags;
        int ret;

        array_size = (unsigned long)nr_small_pages * sizeof(struct page *);

        if (!(gfp_mask & (GFP_DMA | GFP_DMA32)))
                gfp_mask |= __GFP_HIGHMEM;

        /* Please note that the recursion is strictly bounded. */
        if (array_size > PAGE_SIZE) {
                area->pages = __vmalloc_node(array_size, 1, nested_gfp, node,
                                        area->caller);
        } else {
                area->pages = kmalloc_node(array_size, nested_gfp, node);
        }

        if (!area->pages) {
                warn_alloc(gfp_mask, NULL,
                        "vmalloc error: size %lu, failed to allocated page array size %lu",
                        nr_small_pages * PAGE_SIZE, array_size);
                free_vm_area(area);
                return NULL;
        }

        set_vm_area_page_order(area, page_shift - PAGE_SHIFT);
        page_order = vm_area_page_order(area);

        area->nr_pages = vm_area_alloc_pages(gfp_mask | __GFP_NOWARN,
                node, page_order, nr_small_pages, area->pages);

        atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
        if (gfp_mask & __GFP_ACCOUNT) {
                int i;

                for (i = 0; i < area->nr_pages; i++)
                        mod_memcg_page_state(area->pages[i], MEMCG_VMALLOC, 1);
        }

        /*
         * If not enough pages were obtained to accomplish an
         * allocation request, free them via vfree() if any.
         */
        if (area->nr_pages != nr_small_pages) {
                /*
                 * vm_area_alloc_pages() can fail due to insufficient memory but
                 * also:-
                 *
                 * - a pending fatal signal
                 * - insufficient huge page-order pages
                 *
                 * Since we always retry allocations at order-0 in the huge page
                 * case a warning for either is spurious.
                 */
                if (!fatal_signal_pending(current) && page_order == 0)
                        warn_alloc(gfp_mask, NULL,
                                "vmalloc error: size %lu, failed to allocate pages",
                                area->nr_pages * PAGE_SIZE);
                goto fail;
        }

        /*
         * page tables allocations ignore external gfp mask, enforce it
         * by the scope API
         */
        if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
                flags = memalloc_nofs_save();
        else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
                flags = memalloc_noio_save();

        do {
                ret = vmap_pages_range(addr, addr + size, prot, area->pages,
                        page_shift);
                if (nofail && (ret < 0))
                        schedule_timeout_uninterruptible(1);
        } while (nofail && (ret < 0));

        if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
                memalloc_nofs_restore(flags);
        else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
                memalloc_noio_restore(flags);

        if (ret < 0) {
                warn_alloc(gfp_mask, NULL,
                        "vmalloc error: size %lu, failed to map pages",
                        area->nr_pages * PAGE_SIZE);
                goto fail;
        }

        return area->addr;

fail:
        vfree(area->addr);
        return NULL;
}

/**
 * __vmalloc_node_range - allocate virtually contiguous memory
 * @size:                 allocation size
 * @align:                desired alignment
 * @start:                vm area range start
 * @end:                  vm area range end
 * @gfp_mask:             flags for the page level allocator
 * @prot:                 protection mask for the allocated pages
 * @vm_flags:             additional vm area flags (e.g. %VM_NO_GUARD)
 * @node:                 node to use for allocation or NUMA_NO_NODE
 * @caller:               caller's return address
 *
 * Allocate enough pages to cover @size from the page level
 * allocator with @gfp_mask flags. Please note that the full set of gfp
 * flags are not supported. GFP_KERNEL, GFP_NOFS and GFP_NOIO are all
 * supported.
 * Zone modifiers are not supported. From the reclaim modifiers
 * __GFP_DIRECT_RECLAIM is required (aka GFP_NOWAIT is not supported)
 * and only __GFP_NOFAIL is supported (i.e. __GFP_NORETRY and
 * __GFP_RETRY_MAYFAIL are not supported).
 *
 * __GFP_NOWARN can be used to suppress failures messages.
 *
 * Map them into contiguous kernel virtual space, using a pagetable
 * protection of @prot.
 *
 * Return: the address of the area or %NULL on failure
 */
void *__vmalloc_node_range(unsigned long size, unsigned long align,
                        unsigned long start, unsigned long end, gfp_t gfp_mask,
                        pgprot_t prot, unsigned long vm_flags, int node,
                        const void *caller)
{
        struct vm_struct *area;
        void *ret;
        kasan_vmalloc_flags_t kasan_flags = KASAN_VMALLOC_NONE;
        unsigned long real_size = size;
        unsigned long real_align = align;
        unsigned int shift = PAGE_SHIFT;

        if (WARN_ON_ONCE(!size))
                return NULL;

        if ((size >> PAGE_SHIFT) > totalram_pages()) {
                warn_alloc(gfp_mask, NULL,
                        "vmalloc error: size %lu, exceeds total pages",
                        real_size);
                return NULL;
        }

        if (vmap_allow_huge && (vm_flags & VM_ALLOW_HUGE_VMAP)) {
                unsigned long size_per_node;

                /*
                 * Try huge pages. Only try for PAGE_KERNEL allocations,
                 * others like modules don't yet expect huge pages in
                 * their allocations due to apply_to_page_range not
                 * supporting them.
                 */

                size_per_node = size;
                if (node == NUMA_NO_NODE)
                        size_per_node /= num_online_nodes();
                if (arch_vmap_pmd_supported(prot) && size_per_node >= PMD_SIZE)
                        shift = PMD_SHIFT;
                else
                        shift = arch_vmap_pte_supported_shift(size_per_node);

                align = max(real_align, 1UL << shift);
                size = ALIGN(real_size, 1UL << shift);
        }

again:
        area = __get_vm_area_node(real_size, align, shift, VM_ALLOC |
                                  VM_UNINITIALIZED | vm_flags, start, end, node,
                                  gfp_mask, caller);
        if (!area) {
                bool nofail = gfp_mask & __GFP_NOFAIL;
                warn_alloc(gfp_mask, NULL,
                        "vmalloc error: size %lu, vm_struct allocation failed%s",
                        real_size, (nofail) ? ". Retrying." : "");
                if (nofail) {
                        schedule_timeout_uninterruptible(1);
                        goto again;
                }
                goto fail;
        }

        /*
         * Prepare arguments for __vmalloc_area_node() and
         * kasan_unpoison_vmalloc().
         */
        if (pgprot_val(prot) == pgprot_val(PAGE_KERNEL)) {
                if (kasan_hw_tags_enabled()) {
                        /*
                         * Modify protection bits to allow tagging.
                         * This must be done before mapping.
                         */
                        prot = arch_vmap_pgprot_tagged(prot);

                        /*
                         * Skip page_alloc poisoning and zeroing for physical
                         * pages backing VM_ALLOC mapping. Memory is instead
                         * poisoned and zeroed by kasan_unpoison_vmalloc().
                         */
                        gfp_mask |= __GFP_SKIP_KASAN | __GFP_SKIP_ZERO;
                }

                /* Take note that the mapping is PAGE_KERNEL. */
                kasan_flags |= KASAN_VMALLOC_PROT_NORMAL;
        }

        /* Allocate physical pages and map them into vmalloc space. */
        ret = __vmalloc_area_node(area, gfp_mask, prot, shift, node);
        if (!ret)
                goto fail;

        /*
         * Mark the pages as accessible, now that they are mapped.
         * The condition for setting KASAN_VMALLOC_INIT should complement the
         * one in post_alloc_hook() with regards to the __GFP_SKIP_ZERO check
         * to make sure that memory is initialized under the same conditions.
         * Tag-based KASAN modes only assign tags to normal non-executable
         * allocations, see __kasan_unpoison_vmalloc().
         */
        kasan_flags |= KASAN_VMALLOC_VM_ALLOC;
        if (!want_init_on_free() && want_init_on_alloc(gfp_mask) &&
            (gfp_mask & __GFP_SKIP_ZERO))
                kasan_flags |= KASAN_VMALLOC_INIT;
        /* KASAN_VMALLOC_PROT_NORMAL already set if required. */
        area->addr = kasan_unpoison_vmalloc(area->addr, real_size, kasan_flags);

        /*
         * In this function, newly allocated vm_struct has VM_UNINITIALIZED
         * flag. It means that vm_struct is not fully initialized.
         * Now, it is fully initialized, so remove this flag here.
         */
        clear_vm_uninitialized_flag(area);

        size = PAGE_ALIGN(size);
        if (!(vm_flags & VM_DEFER_KMEMLEAK))
                kmemleak_vmalloc(area, size, gfp_mask);

        return area->addr;

fail:
        if (shift > PAGE_SHIFT) {
                shift = PAGE_SHIFT;
                align = real_align;
                size = real_size;
                goto again;
        }

        return NULL;
}

/**
 * __vmalloc_node - allocate virtually contiguous memory
 * @size:           allocation size
 * @align:          desired alignment
 * @gfp_mask:       flags for the page level allocator
 * @node:           node to use for allocation or NUMA_NO_NODE
 * @caller:         caller's return address
 *
 * Allocate enough pages to cover @size from the page level allocator with
 * @gfp_mask flags.  Map them into contiguous kernel virtual space.
 *
 * Reclaim modifiers in @gfp_mask - __GFP_NORETRY, __GFP_RETRY_MAYFAIL
 * and __GFP_NOFAIL are not supported
 *
 * Any use of gfp flags outside of GFP_KERNEL should be consulted
 * with mm people.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *__vmalloc_node(unsigned long size, unsigned long align,
                            gfp_t gfp_mask, int node, const void *caller)
{
        return __vmalloc_node_range(size, align, VMALLOC_START, VMALLOC_END,
                                gfp_mask, PAGE_KERNEL, 0, node, caller);
}
/*
 * This is only for performance analysis of vmalloc and stress purpose.
 * It is required by vmalloc test module, therefore do not use it other
 * than that.
 */
#ifdef CONFIG_TEST_VMALLOC_MODULE
EXPORT_SYMBOL_GPL(__vmalloc_node);
#endif

void *__vmalloc(unsigned long size, gfp_t gfp_mask)
{
        return __vmalloc_node(size, 1, gfp_mask, NUMA_NO_NODE,
                                __builtin_return_address(0));
}
EXPORT_SYMBOL(__vmalloc);

/**
 * vmalloc - allocate virtually contiguous memory
 * @size:    allocation size
 *
 * Allocate enough pages to cover @size from the page level
 * allocator and map them into contiguous kernel virtual space.
 *
 * For tight control over page level allocator and protection flags
 * use __vmalloc() instead.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *vmalloc(unsigned long size)
{
        return __vmalloc_node(size, 1, GFP_KERNEL, NUMA_NO_NODE,
                                __builtin_return_address(0));
}
EXPORT_SYMBOL(vmalloc);

/**
 * vmalloc_huge - allocate virtually contiguous memory, allow huge pages
 * @size:      allocation size
 * @gfp_mask:  flags for the page level allocator
 *
 * Allocate enough pages to cover @size from the page level
 * allocator and map them into contiguous kernel virtual space.
 * If @size is greater than or equal to PMD_SIZE, allow using
 * huge pages for the memory
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *vmalloc_huge(unsigned long size, gfp_t gfp_mask)
{
        return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
                                    gfp_mask, PAGE_KERNEL, VM_ALLOW_HUGE_VMAP,
                                    NUMA_NO_NODE, __builtin_return_address(0));
}
EXPORT_SYMBOL_GPL(vmalloc_huge);

/**
 * vzalloc - allocate virtually contiguous memory with zero fill
 * @size:    allocation size
 *
 * Allocate enough pages to cover @size from the page level
 * allocator and map them into contiguous kernel virtual space.
 * The memory allocated is set to zero.
 *
 * For tight control over page level allocator and protection flags
 * use __vmalloc() instead.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *vzalloc(unsigned long size)
{
        return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_ZERO, NUMA_NO_NODE,
                                __builtin_return_address(0));
}
EXPORT_SYMBOL(vzalloc);

/**
 * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
 * @size: allocation size
 *
 * The resulting memory area is zeroed so it can be mapped to userspace
 * without leaking data.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *vmalloc_user(unsigned long size)
{
        return __vmalloc_node_range(size, SHMLBA,  VMALLOC_START, VMALLOC_END,
                                    GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL,
                                    VM_USERMAP, NUMA_NO_NODE,
                                    __builtin_return_address(0));
}
EXPORT_SYMBOL(vmalloc_user);

/**
 * vmalloc_node - allocate memory on a specific node
 * @size:         allocation size
 * @node:         numa node
 *
 * Allocate enough pages to cover @size from the page level
 * allocator and map them into contiguous kernel virtual space.
 *
 * For tight control over page level allocator and protection flags
 * use __vmalloc() instead.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *vmalloc_node(unsigned long size, int node)
{
        return __vmalloc_node(size, 1, GFP_KERNEL, node,
                        __builtin_return_address(0));
}
EXPORT_SYMBOL(vmalloc_node);

/**
 * vzalloc_node - allocate memory on a specific node with zero fill
 * @size:       allocation size
 * @node:       numa node
 *
 * Allocate enough pages to cover @size from the page level
 * allocator and map them into contiguous kernel virtual space.
 * The memory allocated is set to zero.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *vzalloc_node(unsigned long size, int node)
{
        return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_ZERO, node,
                                __builtin_return_address(0));
}
EXPORT_SYMBOL(vzalloc_node);

#if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
#define GFP_VMALLOC32 (GFP_DMA32 | GFP_KERNEL)
#elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
#define GFP_VMALLOC32 (GFP_DMA | GFP_KERNEL)
#else
/*
 * 64b systems should always have either DMA or DMA32 zones. For others
 * GFP_DMA32 should do the right thing and use the normal zone.
 */
#define GFP_VMALLOC32 (GFP_DMA32 | GFP_KERNEL)
#endif

/**
 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
 * @size:       allocation size
 *
 * Allocate enough 32bit PA addressable pages to cover @size from the
 * page level allocator and map them into contiguous kernel virtual space.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *vmalloc_32(unsigned long size)
{
        return __vmalloc_node(size, 1, GFP_VMALLOC32, NUMA_NO_NODE,
                        __builtin_return_address(0));
}
EXPORT_SYMBOL(vmalloc_32);

/**
 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 * @size:            allocation size
 *
 * The resulting memory area is 32bit addressable and zeroed so it can be
 * mapped to userspace without leaking data.
 *
 * Return: pointer to the allocated memory or %NULL on error
 */
void *vmalloc_32_user(unsigned long size)
{
        return __vmalloc_node_range(size, SHMLBA,  VMALLOC_START, VMALLOC_END,
                                    GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL,
                                    VM_USERMAP, NUMA_NO_NODE,
                                    __builtin_return_address(0));
}
EXPORT_SYMBOL(vmalloc_32_user);

/*
 * Atomically zero bytes in the iterator.
 *
 * Returns the number of zeroed bytes.
 */
static size_t zero_iter(struct iov_iter *iter, size_t count)
{
        size_t remains = count;

        while (remains > 0) {
                size_t num, copied;

                num = min_t(size_t, remains, PAGE_SIZE);
                copied = copy_page_to_iter_nofault(ZERO_PAGE(0), 0, num, iter);
                remains -= copied;

                if (copied < num)
                        break;
        }

        return count - remains;
}

/*
 * small helper routine, copy contents to iter from addr.
 * If the page is not present, fill zero.
 *
 * Returns the number of copied bytes.
 */
static size_t aligned_vread_iter(struct iov_iter *iter,
                                 const char *addr, size_t count)
{
        size_t remains = count;
        struct page *page;

        while (remains > 0) {
                unsigned long offset, length;
                size_t copied = 0;

                offset = offset_in_page(addr);
                length = PAGE_SIZE - offset;
                if (length > remains)
                        length = remains;
                page = vmalloc_to_page(addr);
                /*
                 * To do safe access to this _mapped_ area, we need lock. But
                 * adding lock here means that we need to add overhead of
                 * vmalloc()/vfree() calls for this _debug_ interface, rarely
                 * used. Instead of that, we'll use an local mapping via
                 * copy_page_to_iter_nofault() and accept a small overhead in
                 * this access function.
                 */
                if (page)
                        copied = copy_page_to_iter_nofault(page, offset,
                                                           length, iter);
                else
                        copied = zero_iter(iter, length);

                addr += copied;
                remains -= copied;

                if (copied != length)
                        break;
        }

        return count - remains;
}

/*
 * Read from a vm_map_ram region of memory.
 *
 * Returns the number of copied bytes.
 */
static size_t vmap_ram_vread_iter(struct iov_iter *iter, const char *addr,
                                  size_t count, unsigned long flags)
{
        char *start;
        struct vmap_block *vb;
        struct xarray *xa;
        unsigned long offset;
        unsigned int rs, re;
        size_t remains, n;

        /*
         * If it's area created by vm_map_ram() interface directly, but
         * not further subdividing and delegating management to vmap_block,
         * handle it here.
         */
        if (!(flags & VMAP_BLOCK))
                return aligned_vread_iter(iter, addr, count);

        remains = count;

        /*
         * Area is split into regions and tracked with vmap_block, read out
         * each region and zero fill the hole between regions.
         */
        xa = addr_to_vb_xa((unsigned long) addr);
        vb = xa_load(xa, addr_to_vb_idx((unsigned long)addr));
        if (!vb)
                goto finished_zero;

        spin_lock(&vb->lock);
        if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) {
                spin_unlock(&vb->lock);
                goto finished_zero;
        }

        for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) {
                size_t copied;

                if (remains == 0)
                        goto finished;

                start = vmap_block_vaddr(vb->va->va_start, rs);

                if (addr < start) {
                        size_t to_zero = min_t(size_t, start - addr, remains);
                        size_t zeroed = zero_iter(iter, to_zero);

                        addr += zeroed;
                        remains -= zeroed;

                        if (remains == 0 || zeroed != to_zero)
                                goto finished;
                }

                /*it could start reading from the middle of used region*/
                offset = offset_in_page(addr);
                n = ((re - rs + 1) << PAGE_SHIFT) - offset;
                if (n > remains)
                        n = remains;

                copied = aligned_vread_iter(iter, start + offset, n);

                addr += copied;
                remains -= copied;

                if (copied != n)
                        goto finished;
        }

        spin_unlock(&vb->lock);

finished_zero:
        /* zero-fill the left dirty or free regions */
        return count - remains + zero_iter(iter, remains);
finished:
        /* We couldn't copy/zero everything */
        spin_unlock(&vb->lock);
        return count - remains;
}

/**
 * vread_iter() - read vmalloc area in a safe way to an iterator.
 * @iter:         the iterator to which data should be written.
 * @addr:         vm address.
 * @count:        number of bytes to be read.
 *
 * This function checks that addr is a valid vmalloc'ed area, and
 * copy data from that area to a given buffer. If the given memory range
 * of [addr...addr+count) includes some valid address, data is copied to
 * proper area of @buf. If there are memory holes, they'll be zero-filled.
 * IOREMAP area is treated as memory hole and no copy is done.
 *
 * If [addr...addr+count) doesn't includes any intersects with alive
 * vm_struct area, returns 0. @buf should be kernel's buffer.
 *
 * Note: In usual ops, vread() is never necessary because the caller
 * should know vmalloc() area is valid and can use memcpy().
 * This is for routines which have to access vmalloc area without
 * any information, as /proc/kcore.
 *
 * Return: number of bytes for which addr and buf should be increased
 * (same number as @count) or %0 if [addr...addr+count) doesn't
 * include any intersection with valid vmalloc area
 */
long vread_iter(struct iov_iter *iter, const char *addr, size_t count)
{
        struct vmap_area *va;
        struct vm_struct *vm;
        char *vaddr;
        size_t n, size, flags, remains;

        addr = kasan_reset_tag(addr);

        /* Don't allow overflow */
        if ((unsigned long) addr + count < count)
                count = -(unsigned long) addr;

        remains = count;

        spin_lock(&vmap_area_lock);
        va = find_vmap_area_exceed_addr((unsigned long)addr);
        if (!va)
                goto finished_zero;

        /* no intersects with alive vmap_area */
        if ((unsigned long)addr + remains <= va->va_start)
                goto finished_zero;

        list_for_each_entry_from(va, &vmap_area_list, list) {
                size_t copied;

                if (remains == 0)
                        goto finished;

                vm = va->vm;
                flags = va->flags & VMAP_FLAGS_MASK;
                /*
                 * VMAP_BLOCK indicates a sub-type of vm_map_ram area, need
                 * be set together with VMAP_RAM.
                 */
                WARN_ON(flags == VMAP_BLOCK);

                if (!vm && !flags)
                        continue;

                if (vm && (vm->flags & VM_UNINITIALIZED))
                        continue;

                /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
                smp_rmb();

                vaddr = (char *) va->va_start;
                size = vm ? get_vm_area_size(vm) : va_size(va);

                if (addr >= vaddr + size)
                        continue;

                if (addr < vaddr) {
                        size_t to_zero = min_t(size_t, vaddr - addr, remains);
                        size_t zeroed = zero_iter(iter, to_zero);

                        addr += zeroed;
                        remains -= zeroed;

                        if (remains == 0 || zeroed != to_zero)
                                goto finished;
                }

                n = vaddr + size - addr;
                if (n > remains)
                        n = remains;

                if (flags & VMAP_RAM)
                        copied = vmap_ram_vread_iter(iter, addr, n, flags);
                else if (!(vm && (vm->flags & (VM_IOREMAP | VM_SPARSE))))
                        copied = aligned_vread_iter(iter, addr, n);
                else /* IOREMAP | SPARSE area is treated as memory hole */
                        copied = zero_iter(iter, n);

                addr += copied;
                remains -= copied;

                if (copied != n)
                        goto finished;
        }

finished_zero:
        spin_unlock(&vmap_area_lock);
        /* zero-fill memory holes */
        return count - remains + zero_iter(iter, remains);
finished:
        /* Nothing remains, or We couldn't copy/zero everything. */
        spin_unlock(&vmap_area_lock);

        return count - remains;
}

/**
 * remap_vmalloc_range_partial - map vmalloc pages to userspace
 * @vma:                vma to cover
 * @uaddr:              target user address to start at
 * @kaddr:              virtual address of vmalloc kernel memory
 * @pgoff:              offset from @kaddr to start at
 * @size:               size of map area
 *
 * Returns:     0 for success, -Exxx on failure
 *
 * This function checks that @kaddr is a valid vmalloc'ed area,
 * and that it is big enough to cover the range starting at
 * @uaddr in @vma. Will return failure if that criteria isn't
 * met.
 *
 * Similar to remap_pfn_range() (see mm/memory.c)
 */
int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
                                void *kaddr, unsigned long pgoff,
                                unsigned long size)
{
        struct vm_struct *area;
        unsigned long off;
        unsigned long end_index;

        if (check_shl_overflow(pgoff, PAGE_SHIFT, &off))
                return -EINVAL;

        size = PAGE_ALIGN(size);

        if (!PAGE_ALIGNED(uaddr) || !PAGE_ALIGNED(kaddr))
                return -EINVAL;

        area = find_vm_area(kaddr);
        if (!area)
                return -EINVAL;

        if (!(area->flags & (VM_USERMAP | VM_DMA_COHERENT)))
                return -EINVAL;

        if (check_add_overflow(size, off, &end_index) ||
            end_index > get_vm_area_size(area))
                return -EINVAL;
        kaddr += off;

        do {
                struct page *page = vmalloc_to_page(kaddr);
                int ret;

                ret = vm_insert_page(vma, uaddr, page);
                if (ret)
                        return ret;

                uaddr += PAGE_SIZE;
                kaddr += PAGE_SIZE;
                size -= PAGE_SIZE;
        } while (size > 0);

        vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP);

        return 0;
}

/**
 * remap_vmalloc_range - map vmalloc pages to userspace
 * @vma:                vma to cover (map full range of vma)
 * @addr:               vmalloc memory
 * @pgoff:              number of pages into addr before first page to map
 *
 * Returns:     0 for success, -Exxx on failure
 *
 * This function checks that addr is a valid vmalloc'ed area, and
 * that it is big enough to cover the vma. Will return failure if
 * that criteria isn't met.
 *
 * Similar to remap_pfn_range() (see mm/memory.c)
 */
int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
                                                unsigned long pgoff)
{
        return remap_vmalloc_range_partial(vma, vma->vm_start,
                                           addr, pgoff,
                                           vma->vm_end - vma->vm_start);
}
EXPORT_SYMBOL(remap_vmalloc_range);

void free_vm_area(struct vm_struct *area)
{
        struct vm_struct *ret;
        ret = remove_vm_area(area->addr);
        BUG_ON(ret != area);
        kfree(area);
}
EXPORT_SYMBOL_GPL(free_vm_area);

#ifdef CONFIG_SMP
static struct vmap_area *node_to_va(struct rb_node *n)
{
        return rb_entry_safe(n, struct vmap_area, rb_node);
}

/**
 * pvm_find_va_enclose_addr - find the vmap_area @addr belongs to
 * @addr: target address
 *
 * Returns: vmap_area if it is found. If there is no such area
 *   the first highest(reverse order) vmap_area is returned
 *   i.e. va->va_start < addr && va->va_end < addr or NULL
 *   if there are no any areas before @addr.
 */
static struct vmap_area *
pvm_find_va_enclose_addr(unsigned long addr)
{
        struct vmap_area *va, *tmp;
        struct rb_node *n;

        n = free_vmap_area_root.rb_node;
        va = NULL;

        while (n) {
                tmp = rb_entry(n, struct vmap_area, rb_node);
                if (tmp->va_start <= addr) {
                        va = tmp;
                        if (tmp->va_end >= addr)
                                break;

                        n = n->rb_right;
                } else {
                        n = n->rb_left;
                }
        }

        return va;
}

/**
 * pvm_determine_end_from_reverse - find the highest aligned address
 * of free block below VMALLOC_END
 * @va:
 *   in - the VA we start the search(reverse order);
 *   out - the VA with the highest aligned end address.
 * @align: alignment for required highest address
 *
 * Returns: determined end address within vmap_area
 */
static unsigned long
pvm_determine_end_from_reverse(struct vmap_area **va, unsigned long align)
{
        unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
        unsigned long addr;

        if (likely(*va)) {
                list_for_each_entry_from_reverse((*va),
                                &free_vmap_area_list, list) {
                        addr = min((*va)->va_end & ~(align - 1), vmalloc_end);
                        if ((*va)->va_start < addr)
                                return addr;
                }
        }

        return 0;
}

/**
 * pcpu_get_vm_areas - allocate vmalloc areas for percpu allocator
 * @offsets: array containing offset of each area
 * @sizes: array containing size of each area
 * @nr_vms: the number of areas to allocate
 * @align: alignment, all entries in @offsets and @sizes must be aligned to this
 *
 * Returns: kmalloc'd vm_struct pointer array pointing to allocated
 *          vm_structs on success, %NULL on failure
 *
 * Percpu allocator wants to use congruent vm areas so that it can
 * maintain the offsets among percpu areas.  This function allocates
 * congruent vmalloc areas for it with GFP_KERNEL.  These areas tend to
 * be scattered pretty far, distance between two areas easily going up
 * to gigabytes.  To avoid interacting with regular vmallocs, these
 * areas are allocated from top.
 *
 * Despite its complicated look, this allocator is rather simple. It
 * does everything top-down and scans free blocks from the end looking
 * for matching base. While scanning, if any of the areas do not fit the
 * base address is pulled down to fit the area. Scanning is repeated till
 * all the areas fit and then all necessary data structures are inserted
 * and the result is returned.
 */
struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
                                     const size_t *sizes, int nr_vms,
                                     size_t align)
{
        const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
        const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
        struct vmap_area **vas, *va;
        struct vm_struct **vms;
        int area, area2, last_area, term_area;
        unsigned long base, start, size, end, last_end, orig_start, orig_end;
        bool purged = false;

        /* verify parameters and allocate data structures */
        BUG_ON(offset_in_page(align) || !is_power_of_2(align));
        for (last_area = 0, area = 0; area < nr_vms; area++) {
                start = offsets[area];
                end = start + sizes[area];

                /* is everything aligned properly? */
                BUG_ON(!IS_ALIGNED(offsets[area], align));
                BUG_ON(!IS_ALIGNED(sizes[area], align));

                /* detect the area with the highest address */
                if (start > offsets[last_area])
                        last_area = area;

                for (area2 = area + 1; area2 < nr_vms; area2++) {
                        unsigned long start2 = offsets[area2];
                        unsigned long end2 = start2 + sizes[area2];

                        BUG_ON(start2 < end && start < end2);
                }
        }
        last_end = offsets[last_area] + sizes[last_area];

        if (vmalloc_end - vmalloc_start < last_end) {
                WARN_ON(true);
                return NULL;
        }

        vms = kcalloc(nr_vms, sizeof(vms[0]), GFP_KERNEL);
        vas = kcalloc(nr_vms, sizeof(vas[0]), GFP_KERNEL);
        if (!vas || !vms)
                goto err_free2;

        for (area = 0; area < nr_vms; area++) {
                vas[area] = kmem_cache_zalloc(vmap_area_cachep, GFP_KERNEL);
                vms[area] = kzalloc(sizeof(struct vm_struct), GFP_KERNEL);
                if (!vas[area] || !vms[area])
                        goto err_free;
        }
retry:
        spin_lock(&free_vmap_area_lock);

        /* start scanning - we scan from the top, begin with the last area */
        area = term_area = last_area;
        start = offsets[area];
        end = start + sizes[area];

        va = pvm_find_va_enclose_addr(vmalloc_end);
        base = pvm_determine_end_from_reverse(&va, align) - end;

        while (true) {
                /*
                 * base might have underflowed, add last_end before
                 * comparing.
                 */
                if (base + last_end < vmalloc_start + last_end)
                        goto overflow;

                /*
                 * Fitting base has not been found.
                 */
                if (va == NULL)
                        goto overflow;

                /*
                 * If required width exceeds current VA block, move
                 * base downwards and then recheck.
                 */
                if (base + end > va->va_end) {
                        base = pvm_determine_end_from_reverse(&va, align) - end;
                        term_area = area;
                        continue;
                }

                /*
                 * If this VA does not fit, move base downwards and recheck.
                 */
                if (base + start < va->va_start) {
                        va = node_to_va(rb_prev(&va->rb_node));
                        base = pvm_determine_end_from_reverse(&va, align) - end;
                        term_area = area;
                        continue;
                }

                /*
                 * This area fits, move on to the previous one.  If
                 * the previous one is the terminal one, we're done.
                 */
                area = (area + nr_vms - 1) % nr_vms;
                if (area == term_area)
                        break;

                start = offsets[area];
                end = start + sizes[area];
                va = pvm_find_va_enclose_addr(base + end);
        }

        /* we've found a fitting base, insert all va's */
        for (area = 0; area < nr_vms; area++) {
                int ret;

                start = base + offsets[area];
                size = sizes[area];

                va = pvm_find_va_enclose_addr(start);
                if (WARN_ON_ONCE(va == NULL))
                        /* It is a BUG(), but trigger recovery instead. */
                        goto recovery;

                ret = adjust_va_to_fit_type(&free_vmap_area_root,
                                            &free_vmap_area_list,
                                            va, start, size);
                if (WARN_ON_ONCE(unlikely(ret)))
                        /* It is a BUG(), but trigger recovery instead. */
                        goto recovery;

                /* Allocated area. */
                va = vas[area];
                va->va_start = start;
                va->va_end = start + size;
        }

        spin_unlock(&free_vmap_area_lock);

        /* populate the kasan shadow space */
        for (area = 0; area < nr_vms; area++) {
                if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area]))
                        goto err_free_shadow;
        }

        /* insert all vm's */
        spin_lock(&vmap_area_lock);
        for (area = 0; area < nr_vms; area++) {
                insert_vmap_area(vas[area], &vmap_area_root, &vmap_area_list);

                setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
                                 pcpu_get_vm_areas);
        }
        spin_unlock(&vmap_area_lock);

        /*
         * Mark allocated areas as accessible. Do it now as a best-effort
         * approach, as they can be mapped outside of vmalloc code.
         * With hardware tag-based KASAN, marking is skipped for
         * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc().
         */
        for (area = 0; area < nr_vms; area++)
                vms[area]->addr = kasan_unpoison_vmalloc(vms[area]->addr,
                                vms[area]->size, KASAN_VMALLOC_PROT_NORMAL);

        kfree(vas);
        return vms;

recovery:
        /*
         * Remove previously allocated areas. There is no
         * need in removing these areas from the busy tree,
         * because they are inserted only on the final step
         * and when pcpu_get_vm_areas() is success.
         */
        while (area--) {
                orig_start = vas[area]->va_start;
                orig_end = vas[area]->va_end;
                va = merge_or_add_vmap_area_augment(vas[area], &free_vmap_area_root,
                                &free_vmap_area_list);
                if (va)
                        kasan_release_vmalloc(orig_start, orig_end,
                                va->va_start, va->va_end);
                vas[area] = NULL;
        }

overflow:
        spin_unlock(&free_vmap_area_lock);
        if (!purged) {
                reclaim_and_purge_vmap_areas();
                purged = true;

                /* Before "retry", check if we recover. */
                for (area = 0; area < nr_vms; area++) {
                        if (vas[area])
                                continue;

                        vas[area] = kmem_cache_zalloc(
                                vmap_area_cachep, GFP_KERNEL);
                        if (!vas[area])
                                goto err_free;
                }

                goto retry;
        }

err_free:
        for (area = 0; area < nr_vms; area++) {
                if (vas[area])
                        kmem_cache_free(vmap_area_cachep, vas[area]);

                kfree(vms[area]);
        }
err_free2:
        kfree(vas);
        kfree(vms);
        return NULL;

err_free_shadow:
        spin_lock(&free_vmap_area_lock);
        /*
         * We release all the vmalloc shadows, even the ones for regions that
         * hadn't been successfully added. This relies on kasan_release_vmalloc
         * being able to tolerate this case.
         */
        for (area = 0; area < nr_vms; area++) {
                orig_start = vas[area]->va_start;
                orig_end = vas[area]->va_end;
                va = merge_or_add_vmap_area_augment(vas[area], &free_vmap_area_root,
                                &free_vmap_area_list);
                if (va)
                        kasan_release_vmalloc(orig_start, orig_end,
                                va->va_start, va->va_end);
                vas[area] = NULL;
                kfree(vms[area]);
        }
        spin_unlock(&free_vmap_area_lock);
        kfree(vas);
        kfree(vms);
        return NULL;
}

/**
 * pcpu_free_vm_areas - free vmalloc areas for percpu allocator
 * @vms: vm_struct pointer array returned by pcpu_get_vm_areas()
 * @nr_vms: the number of allocated areas
 *
 * Free vm_structs and the array allocated by pcpu_get_vm_areas().
 */
void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
{
        int i;

        for (i = 0; i < nr_vms; i++)
                free_vm_area(vms[i]);
        kfree(vms);
}
#endif  /* CONFIG_SMP */

#ifdef CONFIG_PRINTK
bool vmalloc_dump_obj(void *object)
{
        void *objp = (void *)PAGE_ALIGN((unsigned long)object);
        const void *caller;
        struct vm_struct *vm;
        struct vmap_area *va;
        unsigned long addr;
        unsigned int nr_pages;

        if (!spin_trylock(&vmap_area_lock))
                return false;
        va = __find_vmap_area((unsigned long)objp, &vmap_area_root);
        if (!va) {
                spin_unlock(&vmap_area_lock);
                return false;
        }

        vm = va->vm;
        if (!vm) {
                spin_unlock(&vmap_area_lock);
                return false;
        }
        addr = (unsigned long)vm->addr;
        caller = vm->caller;
        nr_pages = vm->nr_pages;
        spin_unlock(&vmap_area_lock);
        pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
                nr_pages, addr, caller);
        return true;
}
#endif

#ifdef CONFIG_PROC_FS
static void *s_start(struct seq_file *m, loff_t *pos)
        __acquires(&vmap_purge_lock)
        __acquires(&vmap_area_lock)
{
        mutex_lock(&vmap_purge_lock);
        spin_lock(&vmap_area_lock);

        return seq_list_start(&vmap_area_list, *pos);
}

static void *s_next(struct seq_file *m, void *p, loff_t *pos)
{
        return seq_list_next(p, &vmap_area_list, pos);
}

static void s_stop(struct seq_file *m, void *p)
        __releases(&vmap_area_lock)
        __releases(&vmap_purge_lock)
{
        spin_unlock(&vmap_area_lock);
        mutex_unlock(&vmap_purge_lock);
}

static void show_numa_info(struct seq_file *m, struct vm_struct *v)
{
        if (IS_ENABLED(CONFIG_NUMA)) {
                unsigned int nr, *counters = m->private;
                unsigned int step = 1U << vm_area_page_order(v);

                if (!counters)
                        return;

                if (v->flags & VM_UNINITIALIZED)
                        return;
                /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
                smp_rmb();

                memset(counters, 0, nr_node_ids * sizeof(unsigned int));

                for (nr = 0; nr < v->nr_pages; nr += step)
                        counters[page_to_nid(v->pages[nr])] += step;
                for_each_node_state(nr, N_HIGH_MEMORY)
                        if (counters[nr])
                                seq_printf(m, " N%u=%u", nr, counters[nr]);
        }
}

static void show_purge_info(struct seq_file *m)
{
        struct vmap_area *va;

        spin_lock(&purge_vmap_area_lock);
        list_for_each_entry(va, &purge_vmap_area_list, list) {
                seq_printf(m, "0x%pK-0x%pK %7ld unpurged vm_area\n",
                        (void *)va->va_start, (void *)va->va_end,
                        va->va_end - va->va_start);
        }
        spin_unlock(&purge_vmap_area_lock);
}

static int s_show(struct seq_file *m, void *p)
{
        struct vmap_area *va;
        struct vm_struct *v;

        va = list_entry(p, struct vmap_area, list);

        if (!va->vm) {
                if (va->flags & VMAP_RAM)
                        seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
                                (void *)va->va_start, (void *)va->va_end,
                                va->va_end - va->va_start);

                goto final;
        }

        v = va->vm;

        seq_printf(m, "0x%pK-0x%pK %7ld",
                v->addr, v->addr + v->size, v->size);

        if (v->caller)
                seq_printf(m, " %pS", v->caller);

        if (v->nr_pages)
                seq_printf(m, " pages=%d", v->nr_pages);

        if (v->phys_addr)
                seq_printf(m, " phys=%pa", &v->phys_addr);

        if (v->flags & VM_IOREMAP)
                seq_puts(m, " ioremap");

        if (v->flags & VM_SPARSE)
                seq_puts(m, " sparse");

        if (v->flags & VM_ALLOC)
                seq_puts(m, " vmalloc");

        if (v->flags & VM_MAP)
                seq_puts(m, " vmap");

        if (v->flags & VM_USERMAP)
                seq_puts(m, " user");

        if (v->flags & VM_DMA_COHERENT)
                seq_puts(m, " dma-coherent");

        if (is_vmalloc_addr(v->pages))
                seq_puts(m, " vpages");

        show_numa_info(m, v);
        seq_putc(m, '\n');

        /*
         * As a final step, dump "unpurged" areas.
         */
final:
        if (list_is_last(&va->list, &vmap_area_list))
                show_purge_info(m);

        return 0;
}

static const struct seq_operations vmalloc_op = {
        .start = s_start,
        .next = s_next,
        .stop = s_stop,
        .show = s_show,
};

static int __init proc_vmalloc_init(void)
{
        if (IS_ENABLED(CONFIG_NUMA))
                proc_create_seq_private("vmallocinfo", 0400, NULL,
                                &vmalloc_op,
                                nr_node_ids * sizeof(unsigned int), NULL);
        else
                proc_create_seq("vmallocinfo", 0400, NULL, &vmalloc_op);
        return 0;
}
module_init(proc_vmalloc_init);

#endif

void __init vmalloc_init(void)
{
        struct vmap_area *va;
        struct vm_struct *tmp;
        int i;

        /*
         * Create the cache for vmap_area objects.
         */
        vmap_area_cachep = KMEM_CACHE(vmap_area, SLAB_PANIC);

        for_each_possible_cpu(i) {
                struct vmap_block_queue *vbq;
                struct vfree_deferred *p;

                vbq = &per_cpu(vmap_block_queue, i);
                spin_lock_init(&vbq->lock);
                INIT_LIST_HEAD(&vbq->free);
                p = &per_cpu(vfree_deferred, i);
                init_llist_head(&p->list);
                INIT_WORK(&p->wq, delayed_vfree_work);
                xa_init(&vbq->vmap_blocks);
        }

        /* Import existing vmlist entries. */
        for (tmp = vmlist; tmp; tmp = tmp->next) {
                va = kmem_cache_zalloc(vmap_area_cachep, GFP_NOWAIT);
                if (WARN_ON_ONCE(!va))
                        continue;

                va->va_start = (unsigned long)tmp->addr;
                va->va_end = va->va_start + tmp->size;
                va->vm = tmp;
                insert_vmap_area(va, &vmap_area_root, &vmap_area_list);
        }

        /*
         * Now we can initialize a free vmap space.
         */
        vmap_init_free_space();
        vmap_initialized = true;
}