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mm: convert page_try_share_anon_rmap() to folio_try_share_anon_rmap_[pte|pmd]()

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Let's convert it like we converted all the other rmap functions.  Don't
introduce folio_try_share_anon_rmap_ptes() for now, as we don't have a
user that wants rmap batching in sight.  Pretty easy to add later.

All users are easy to convert -- only ksm.c doesn't use folios yet but
that is left for future work -- so let's just do it in a single shot.

While at it, turn the BUG_ON into a WARN_ON_ONCE.

Note that page_try_share_anon_rmap() so far didn't care about pte/pmd
mappings (no compound parameter).  We're changing that so we can perform
better sanity checks and make the code actually more readable/consistent. 
For example, __folio_rmap_sanity_checks() will make sure that a PMD range
actually falls completely into the folio.

Link: https://lkml.kernel.org/r/20231220224504.646757-39-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2023-12-20 23:45:02 +01:00 committed by Andrew Morton
parent a13d096471
commit e3b4b1374f
7 changed files with 89 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

96
include/linux/rmap.h
View File

@ -269,7 +269,7 @@ static inline int hugetlb_try_dup_anon_rmap(struct folio *folio,
return 0;
}
/* See page_try_share_anon_rmap() */
/* See folio_try_share_anon_rmap_*() */
static inline int hugetlb_try_share_anon_rmap(struct folio *folio)
{
VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
@ -478,31 +478,15 @@ static inline int folio_try_dup_anon_rmap_pmd(struct folio *folio,
#endif
}
/**
* page_try_share_anon_rmap - try marking an exclusive anonymous page possibly
* shared to prepare for KSM or temporary unmapping
* @page: the exclusive anonymous page to try marking possibly shared
*
* The caller needs to hold the PT lock and has to have the page table entry
* cleared/invalidated.
*
* This is similar to folio_try_dup_anon_rmap_*(), however, not used during
* fork() to duplicate a mapping, but instead to prepare for KSM or temporarily
* unmapping a page (swap, migration) via folio_remove_rmap_*().
*
* Marking the page shared can only fail if the page may be pinned; device
* private pages cannot get pinned and consequently this function cannot fail.
*
* Returns 0 if marking the page possibly shared succeeded. Returns -EBUSY
* otherwise.
*/
static inline int page_try_share_anon_rmap(struct page *page)
static __always_inline int __folio_try_share_anon_rmap(struct folio *folio,
struct page *page, int nr_pages, enum rmap_level level)
{
VM_WARN_ON(folio_test_hugetlb(page_folio(page)));
VM_BUG_ON_PAGE(!PageAnon(page) || !PageAnonExclusive(page), page);
VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
VM_WARN_ON_FOLIO(!PageAnonExclusive(page), folio);
__folio_rmap_sanity_checks(folio, page, nr_pages, level);
/* device private pages cannot get pinned via GUP. */
if (unlikely(is_device_private_page(page))) {
/* device private folios cannot get pinned via GUP. */
if (unlikely(folio_is_device_private(folio))) {
ClearPageAnonExclusive(page);
return 0;
}
@ -553,7 +537,7 @@ static inline int page_try_share_anon_rmap(struct page *page)
if (IS_ENABLED(CONFIG_HAVE_FAST_GUP))
smp_mb();
if (unlikely(page_maybe_dma_pinned(page)))
if (unlikely(folio_maybe_dma_pinned(folio)))
return -EBUSY;
ClearPageAnonExclusive(page);
@ -566,6 +550,68 @@ static inline int page_try_share_anon_rmap(struct page *page)
return 0;
}
/**
* folio_try_share_anon_rmap_pte - try marking an exclusive anonymous page
* mapped by a PTE possibly shared to prepare
* for KSM or temporary unmapping
* @folio: The folio to share a mapping of
* @page: The mapped exclusive page
*
* The caller needs to hold the page table lock and has to have the page table
* entries cleared/invalidated.
*
* This is similar to folio_try_dup_anon_rmap_pte(), however, not used during
* fork() to duplicate mappings, but instead to prepare for KSM or temporarily
* unmapping parts of a folio (swap, migration) via folio_remove_rmap_pte().
*
* Marking the mapped page shared can only fail if the folio maybe pinned;
* device private folios cannot get pinned and consequently this function cannot
* fail.
*
* Returns 0 if marking the mapped page possibly shared succeeded. Returns
* -EBUSY otherwise.
*/
static inline int folio_try_share_anon_rmap_pte(struct folio *folio,
struct page *page)
{
return __folio_try_share_anon_rmap(folio, page, 1, RMAP_LEVEL_PTE);
}
/**
* folio_try_share_anon_rmap_pmd - try marking an exclusive anonymous page
* range mapped by a PMD possibly shared to
* prepare for temporary unmapping
* @folio: The folio to share the mapping of
* @page: The first page to share the mapping of
*
* The page range of the folio is defined by [page, page + HPAGE_PMD_NR)
*
* The caller needs to hold the page table lock and has to have the page table
* entries cleared/invalidated.
*
* This is similar to folio_try_dup_anon_rmap_pmd(), however, not used during
* fork() to duplicate a mapping, but instead to prepare for temporarily
* unmapping parts of a folio (swap, migration) via folio_remove_rmap_pmd().
*
* Marking the mapped pages shared can only fail if the folio maybe pinned;
* device private folios cannot get pinned and consequently this function cannot
* fail.
*
* Returns 0 if marking the mapped pages possibly shared succeeded. Returns
* -EBUSY otherwise.
*/
static inline int folio_try_share_anon_rmap_pmd(struct folio *folio,
struct page *page)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
return __folio_try_share_anon_rmap(folio, page, HPAGE_PMD_NR,
RMAP_LEVEL_PMD);
#else
WARN_ON_ONCE(true);
return -EBUSY;
#endif
}
/*
* Called from mm/vmscan.c to handle paging out
*/

2
mm/gup.c
View File

@ -177,7 +177,7 @@ struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags)
/*
* Adjust the pincount before re-checking the PTE for changes.
* This is essentially a smp_mb() and is paired with a memory
* barrier in page_try_share_anon_rmap().
* barrier in folio_try_share_anon_rmap_*().
*/
smp_mb__after_atomic();

9
mm/huge_memory.c
View File

@ -2523,10 +2523,11 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
* In case we cannot clear PageAnonExclusive(), split the PMD
* only and let try_to_migrate_one() fail later.
*
* See page_try_share_anon_rmap(): invalidate PMD first.
* See folio_try_share_anon_rmap_pmd(): invalidate PMD first.
*/
anon_exclusive = PageAnonExclusive(page);
if (freeze && anon_exclusive && page_try_share_anon_rmap(page))
if (freeze && anon_exclusive &&
folio_try_share_anon_rmap_pmd(folio, page))
freeze = false;
if (!freeze) {
rmap_t rmap_flags = RMAP_NONE;
@ -3554,9 +3555,9 @@ int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
/* See page_try_share_anon_rmap(): invalidate PMD first. */
/* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */
anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page);
if (anon_exclusive && page_try_share_anon_rmap(page)) {
if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) {
set_pmd_at(mm, address, pvmw->pmd, pmdval);
return -EBUSY;
}

4
mm/internal.h
View File

@ -1047,7 +1047,7 @@ enum {
* * Ordinary GUP: Using the PT lock
* * GUP-fast and fork(): mm->write_protect_seq
* * GUP-fast and KSM or temporary unmapping (swap, migration): see
* page_try_share_anon_rmap()
* folio_try_share_anon_rmap_*()
*
* Must be called with the (sub)page that's actually referenced via the
* page table entry, which might not necessarily be the head page for a
@ -1090,7 +1090,7 @@ static inline bool gup_must_unshare(struct vm_area_struct *vma,
return is_cow_mapping(vma->vm_flags);
}
/* Paired with a memory barrier in page_try_share_anon_rmap(). */
/* Paired with a memory barrier in folio_try_share_anon_rmap_*(). */
if (IS_ENABLED(CONFIG_HAVE_FAST_GUP))
smp_rmb();

5
mm/ksm.c
View File

@ -1331,8 +1331,9 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
goto out_unlock;
}
/* See page_try_share_anon_rmap(): clear PTE first. */
if (anon_exclusive && page_try_share_anon_rmap(page)) {
/* See folio_try_share_anon_rmap_pte(): clear PTE first. */
if (anon_exclusive &&
folio_try_share_anon_rmap_pte(page_folio(page), page)) {
set_pte_at(mm, pvmw.address, pvmw.pte, entry);
goto out_unlock;
}

2
mm/migrate_device.c
View File

@ -202,7 +202,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
if (anon_exclusive) {
pte = ptep_clear_flush(vma, addr, ptep);
if (page_try_share_anon_rmap(page)) {
if (folio_try_share_anon_rmap_pte(folio, page)) {
set_pte_at(mm, addr, ptep, pte);
folio_unlock(folio);
folio_put(folio);

11
mm/rmap.c
View File

@ -1866,9 +1866,9 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
break;
}
/* See page_try_share_anon_rmap(): clear PTE first. */
/* See folio_try_share_anon_rmap(): clear PTE first. */
if (anon_exclusive &&
page_try_share_anon_rmap(subpage)) {
folio_try_share_anon_rmap_pte(folio, subpage)) {
swap_free(entry);
set_pte_at(mm, address, pvmw.pte, pteval);
ret = false;
@ -2142,7 +2142,8 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
pte_t swp_pte;
if (anon_exclusive)
BUG_ON(page_try_share_anon_rmap(subpage));
WARN_ON_ONCE(folio_try_share_anon_rmap_pte(folio,
subpage));
/*
* Store the pfn of the page in a special migration
@ -2213,7 +2214,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
VM_BUG_ON_PAGE(pte_write(pteval) && folio_test_anon(folio) &&
!anon_exclusive, subpage);
/* See page_try_share_anon_rmap(): clear PTE first. */
/* See folio_try_share_anon_rmap_pte(): clear PTE first. */
if (folio_test_hugetlb(folio)) {
if (anon_exclusive &&
hugetlb_try_share_anon_rmap(folio)) {
@ -2224,7 +2225,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
break;
}
} else if (anon_exclusive &&
page_try_share_anon_rmap(subpage)) {
folio_try_share_anon_rmap_pte(folio, subpage)) {
set_pte_at(mm, address, pvmw.pte, pteval);
ret = false;
page_vma_mapped_walk_done(&pvmw);