mm: renovate page_address_in_vma()

This function doesn't modify any of its arguments, so if we make a few
other functions take const pointers, we can make page_address_in_vma()
take const pointers too.  All of its callers have the containing folio
already, so pass that in as an argument instead of recalculating it.  Also
add kernel-doc

Link: https://lkml.kernel.org/r/20241005200121.3231142-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index d5e93e44322e50c45ff6896ae34b32c8328e9502..78923015a2e8dfb4d52aa8b63886bc782d232002 100644 (file)
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -728,11 +728,8 @@ page_vma_mapped_walk_restart(struct page_vma_mapped_walk *pvmw)
 }
 
 bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw);
-
-/*
- * Used by swapoff to help locate where page is expected in vma.
- */
-unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
+unsigned long page_address_in_vma(const struct folio *folio,
+               const struct page *, const struct vm_area_struct *);
 
 /*
  * Cleans the PTEs of shared mappings.

diff --git a/mm/internal.h b/mm/internal.h
index cd96848be245cf47fa59c2fc45f7969253eb69b5..8674f677304a99df96878cb9a4589946e93b91db 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -841,7 +841,7 @@ static inline bool free_area_empty(struct free_area *area, int migratetype)
 }
 
 /* mm/util.c */
-struct anon_vma *folio_anon_vma(struct folio *folio);
+struct anon_vma *folio_anon_vma(const struct folio *folio);
 
 #ifdef CONFIG_MMU
 void unmap_mapping_folio(struct folio *folio);
@@ -959,7 +959,7 @@ extern pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma);
  * If any page in this range is mapped by this VMA, return the first address
  * where any of these pages appear.  Otherwise, return -EFAULT.
  */
-static inline unsigned long vma_address(struct vm_area_struct *vma,
+static inline unsigned long vma_address(const struct vm_area_struct *vma,
                pgoff_t pgoff, unsigned long nr_pages)
 {
        unsigned long address;

diff --git a/mm/ksm.c b/mm/ksm.c
index e596bc1b5fa7a1a11a992062b95bc741ef14ba3d..b813225a806d537079203c9ce90373c189e84bd3 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1256,7 +1256,7 @@ static int write_protect_page(struct vm_area_struct *vma, struct folio *folio,
        if (WARN_ON_ONCE(folio_test_large(folio)))
                return err;
 
-       pvmw.address = page_address_in_vma(&folio->page, vma);
+       pvmw.address = page_address_in_vma(folio, folio_page(folio, 0), vma);
        if (pvmw.address == -EFAULT)
                goto out;
 
@@ -1340,7 +1340,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 {
        struct folio *kfolio = page_folio(kpage);
        struct mm_struct *mm = vma->vm_mm;
-       struct folio *folio;
+       struct folio *folio = page_folio(page);
        pmd_t *pmd;
        pmd_t pmde;
        pte_t *ptep;
@@ -1350,7 +1350,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
        int err = -EFAULT;
        struct mmu_notifier_range range;
 
-       addr = page_address_in_vma(page, vma);
+       addr = page_address_in_vma(folio, page, vma);
        if (addr == -EFAULT)
                goto out;
 
@@ -1416,7 +1416,6 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
        ptep_clear_flush(vma, addr, ptep);
        set_pte_at(mm, addr, ptep, newpte);
 
-       folio = page_folio(page);
        folio_remove_rmap_pte(folio, page, vma);
        if (!folio_mapped(folio))
                folio_free_swap(folio);

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 58a3d80961a488b7e3799a797768a60ba9642e3c..ea9d883c01c16fcc6a0e34b2551d5730c36511dc 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -671,7 +671,7 @@ static void collect_procs_file(struct folio *folio, struct page *page,
                         */
                        if (vma->vm_mm != t->mm)
                                continue;
-                       addr = page_address_in_vma(page, vma);
+                       addr = page_address_in_vma(folio, page, vma);
                        add_to_kill_anon_file(t, page, vma, to_kill, addr);
                }
        }

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index a29eff5d0585d79d206898eea9355a05d5ead58a..bb37cd1a51d87f994a08c184161ec6afe5084e8f 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1367,7 +1367,7 @@ static long do_mbind(unsigned long start, unsigned long len,
                        if (!list_entry_is_head(folio, &pagelist, lru)) {
                                vma_iter_init(&vmi, mm, start);
                                for_each_vma_range(vmi, vma, end) {
-                                       addr = page_address_in_vma(
+                                       addr = page_address_in_vma(folio,
                                                folio_page(folio, 0), vma);
                                        if (addr != -EFAULT)
                                                break;

diff --git a/mm/rmap.c b/mm/rmap.c
index e5ec8304a1934a8b99357f21e50822968ca429db..d4e5fe94fa922687fd3e45c0eb902a1d129f37c1 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -767,14 +767,27 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
 }
 #endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
 
-/*
- * At what user virtual address is page expected in vma?
- * Caller should check the page is actually part of the vma.
+/**
+ * page_address_in_vma - The virtual address of a page in this VMA.
+ * @folio: The folio containing the page.
+ * @page: The page within the folio.
+ * @vma: The VMA we need to know the address in.
+ *
+ * Calculates the user virtual address of this page in the specified VMA.
+ * It is the caller's responsibililty to check the page is actually
+ * within the VMA.  There may not currently be a PTE pointing at this
+ * page, but if a page fault occurs at this address, this is the page
+ * which will be accessed.
+ *
+ * Context: Caller should hold a reference to the folio.  Caller should
+ * hold a lock (eg the i_mmap_lock or the mmap_lock) which keeps the
+ * VMA from being altered.
+ *
+ * Return: The virtual address corresponding to this page in the VMA.
  */
-unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
+unsigned long page_address_in_vma(const struct folio *folio,
+               const struct page *page, const struct vm_area_struct *vma)
 {
-       struct folio *folio = page_folio(page);
-
        if (folio_test_anon(folio)) {
                struct anon_vma *page__anon_vma = folio_anon_vma(folio);
                /*
@@ -790,7 +803,7 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
                return -EFAULT;
        }
 
-       /* The !page__anon_vma above handles KSM folios */
+       /* KSM folios don't reach here because of the !page__anon_vma check */
        return vma_address(vma, page_pgoff(folio, page), 1);
 }
 

diff --git a/mm/util.c b/mm/util.c
index 4f1275023eb7317973c061da950ef582f1660c28..60017d2a9e48946418d1842efb8e25bfd32a5681 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -820,7 +820,7 @@ void *vcalloc_noprof(size_t n, size_t size)
 }
 EXPORT_SYMBOL(vcalloc_noprof);
 
-struct anon_vma *folio_anon_vma(struct folio *folio)
+struct anon_vma *folio_anon_vma(const struct folio *folio)
 {
        unsigned long mapping = (unsigned long)folio->mapping;