mm: avoid unnecessary use of is_swap_pmd()

PMD 'non-swap' swap entries are currently used for PMD-level migration
entries and device private entries.

To add to the confusion in this terminology we use is_swap_pmd() in an
inconsistent way similar to how is_swap_pte() was being used - sometimes
adopting the convention that !pmd_none(), !pmd_present() implies PMD 'swap'
entry, sometimes not.

This patch handles the low-hanging fruit of cases where we can simply
substitute other predicates for is_swap_pmd().

No functional change intended.

Link: https://lkml.kernel.org/r/8a1704b36a009c18032d5bea4cb68e71448fbbe5.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 8c35ea48a93e05e9d819b1f9daaec8cf513219a3..1bedf7fa5e7998cf3419b26bdf0d84006eb46cda 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1059,10 +1059,12 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
        bool present = false;
        struct folio *folio;
 
+       if (pmd_none(*pmd))
+               return;
        if (pmd_present(*pmd)) {
                page = vm_normal_page_pmd(vma, addr, *pmd);
                present = true;
-       } else if (unlikely(thp_migration_supported() && is_swap_pmd(*pmd))) {
+       } else if (unlikely(thp_migration_supported())) {
                swp_entry_t entry = pmd_to_swp_entry(*pmd);
 
                if (is_pfn_swap_entry(entry))
@@ -2000,6 +2002,9 @@ static int pagemap_pmd_range_thp(pmd_t *pmdp, unsigned long addr,
        if (vma->vm_flags & VM_SOFTDIRTY)
                flags |= PM_SOFT_DIRTY;
 
+       if (pmd_none(pmd))
+               goto populate_pagemap;
+
        if (pmd_present(pmd)) {
                page = pmd_page(pmd);
 
@@ -2010,7 +2015,7 @@ static int pagemap_pmd_range_thp(pmd_t *pmdp, unsigned long addr,
                        flags |= PM_UFFD_WP;
                if (pm->show_pfn)
                        frame = pmd_pfn(pmd) + idx;
-       } else if (thp_migration_supported() && is_swap_pmd(pmd)) {
+       } else if (thp_migration_supported()) {
                swp_entry_t entry = pmd_to_swp_entry(pmd);
                unsigned long offset;
 
@@ -2037,6 +2042,7 @@ static int pagemap_pmd_range_thp(pmd_t *pmdp, unsigned long addr,
                        flags |= PM_FILE;
        }
 
+populate_pagemap:
        for (; addr != end; addr += PAGE_SIZE, idx++) {
                u64 cur_flags = flags;
                pagemap_entry_t pme;
@@ -2399,6 +2405,9 @@ static unsigned long pagemap_thp_category(struct pagemap_scan_private *p,
 {
        unsigned long categories = PAGE_IS_HUGE;
 
+       if (pmd_none(pmd))
+               return categories;
+
        if (pmd_present(pmd)) {
                struct page *page;
 
@@ -2416,7 +2425,7 @@ static unsigned long pagemap_thp_category(struct pagemap_scan_private *p,
                        categories |= PAGE_IS_PFNZERO;
                if (pmd_soft_dirty(pmd))
                        categories |= PAGE_IS_SOFT_DIRTY;
-       } else if (is_swap_pmd(pmd)) {
+       } else {
                swp_entry_t swp;
 
                categories |= PAGE_IS_SWAPPED;

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index a66ac4f2105c55ab7f53a465e17692216862ef1c..3e8dd6ea94dd27ea436989cf3b418e8ee2b5a831 100644 (file)
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -509,7 +509,13 @@ static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
 
 static inline int is_pmd_migration_entry(pmd_t pmd)
 {
-       return is_swap_pmd(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
+       swp_entry_t entry;
+
+       if (pmd_present(pmd))
+               return 0;
+
+       entry = pmd_to_swp_entry(pmd);
+       return is_migration_entry(entry);
 }
 #else  /* CONFIG_ARCH_ENABLE_THP_MIGRATION */
 static inline int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
@@ -557,7 +563,13 @@ static inline int is_pmd_migration_entry(pmd_t pmd)
  */
 static inline int is_pmd_device_private_entry(pmd_t pmd)
 {
-       return is_swap_pmd(pmd) && is_device_private_entry(pmd_to_swp_entry(pmd));
+       swp_entry_t entry;
+
+       if (pmd_present(pmd))
+               return 0;
+
+       entry = pmd_to_swp_entry(pmd);
+       return is_device_private_entry(entry);
 }
 
 #else /* CONFIG_ZONE_DEVICE && CONFIG_ARCH_ENABLE_THP_MIGRATION */

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d79a4bb363de861317ca9ff6f87ce0be8acb0370..b88b4b866cb3a7e64bf8742ee3674130a7e2f9e2 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2354,9 +2354,11 @@ static pmd_t move_soft_dirty_pmd(pmd_t pmd)
 
 static pmd_t clear_uffd_wp_pmd(pmd_t pmd)
 {
+       if (pmd_none(pmd))
+               return pmd;
        if (pmd_present(pmd))
                pmd = pmd_clear_uffd_wp(pmd);
-       else if (is_swap_pmd(pmd))
+       else
                pmd = pmd_swp_clear_uffd_wp(pmd);
 
        return pmd;

diff --git a/mm/memory.c b/mm/memory.c
index 0caf8c5c8c68e501f1f6ecbc2a8a5a30c17a3750..76c17feff88bbe7765dc4513ccbf19be7bf4f63b 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1376,6 +1376,7 @@ copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
                next = pmd_addr_end(addr, end);
                if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)) {
                        int err;
+
                        VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
                        err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
                                            addr, dst_vma, src_vma);
@@ -6340,35 +6341,40 @@ retry_pud:
        if (pmd_none(*vmf.pmd) &&
            thp_vma_allowable_order(vma, vm_flags, TVA_PAGEFAULT, PMD_ORDER)) {
                ret = create_huge_pmd(&vmf);
-               if (!(ret & VM_FAULT_FALLBACK))
+               if (ret & VM_FAULT_FALLBACK)
+                       goto fallback;
+               else
                        return ret;
-       } else {
-               vmf.orig_pmd = pmdp_get_lockless(vmf.pmd);
+       }
 
-               if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
-                       if (is_pmd_device_private_entry(vmf.orig_pmd))
-                               return do_huge_pmd_device_private(&vmf);
+       vmf.orig_pmd = pmdp_get_lockless(vmf.pmd);
+       if (pmd_none(vmf.orig_pmd))
+               goto fallback;
 
-                       if (is_pmd_migration_entry(vmf.orig_pmd))
-                               pmd_migration_entry_wait(mm, vmf.pmd);
-                       return 0;
-               }
-               if (pmd_trans_huge(vmf.orig_pmd)) {
-                       if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
-                               return do_huge_pmd_numa_page(&vmf);
+       if (unlikely(!pmd_present(vmf.orig_pmd))) {
+               if (is_pmd_device_private_entry(vmf.orig_pmd))
+                       return do_huge_pmd_device_private(&vmf);
 
-                       if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
-                           !pmd_write(vmf.orig_pmd)) {
-                               ret = wp_huge_pmd(&vmf);
-                               if (!(ret & VM_FAULT_FALLBACK))
-                                       return ret;
-                       } else {
-                               huge_pmd_set_accessed(&vmf);
-                               return 0;
-                       }
+               if (is_pmd_migration_entry(vmf.orig_pmd))
+                       pmd_migration_entry_wait(mm, vmf.pmd);
+               return 0;
+       }
+       if (pmd_trans_huge(vmf.orig_pmd)) {
+               if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
+                       return do_huge_pmd_numa_page(&vmf);
+
+               if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
+                   !pmd_write(vmf.orig_pmd)) {
+                       ret = wp_huge_pmd(&vmf);
+                       if (!(ret & VM_FAULT_FALLBACK))
+                               return ret;
+               } else {
+                       huge_pmd_set_accessed(&vmf);
+                       return 0;
                }
        }
 
+fallback:
        return handle_pte_fault(&vmf);
 }
 

diff --git a/mm/page_table_check.c b/mm/page_table_check.c
index 43f75d2f7c367111b75c1a85768e52273aa0d34a..f5f25e120f69605b63053e03b9e5a5e8cff00d96 100644 (file)
--- a/mm/page_table_check.c
+++ b/mm/page_table_check.c
@@ -215,10 +215,14 @@ EXPORT_SYMBOL(__page_table_check_ptes_set);
 
 static inline void page_table_check_pmd_flags(pmd_t pmd)
 {
-       if (pmd_present(pmd) && pmd_uffd_wp(pmd))
-               WARN_ON_ONCE(pmd_write(pmd));
-       else if (is_swap_pmd(pmd) && pmd_swp_uffd_wp(pmd))
-               WARN_ON_ONCE(swap_cached_writable(pmd_to_swp_entry(pmd)));
+       if (pmd_present(pmd)) {
+               if (pmd_uffd_wp(pmd))
+                       WARN_ON_ONCE(pmd_write(pmd));
+       } else if (pmd_swp_uffd_wp(pmd)) {
+               swp_entry_t entry = pmd_to_swp_entry(pmd);
+
+               WARN_ON_ONCE(swap_cached_writable(entry));
+       }
 }
 
 void __page_table_check_pmds_set(struct mm_struct *mm, pmd_t *pmdp, pmd_t pmd,