[PATCH v5 07/10] mm/ksm: use folio in write_protect_page

alexs
2024-04-11T06:14:40Z

Compound page is checked and skipped before write_protect_page() called,
use folio to save a few compound_head checking.

Cc: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Alex Shi (tencent) <alexs@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
mm/ksm.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index b127d39c9af0..2fdd6586a3a7 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1289,23 +1289,24 @@ static u32 calc_checksum(struct page *page)
return checksum;
}

-static int write_protect_page(struct vm_area_struct *vma, struct page *page,
+static int write_protect_page(struct vm_area_struct *vma, struct folio *folio,
pte_t *orig_pte)
{
struct mm_struct *mm = vma->vm_mm;
- DEFINE_PAGE_VMA_WALK(pvmw, page, vma, 0, 0);
+ DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, 0, 0);
int swapped;
int err = -EFAULT;
struct mmu_notifier_range range;
bool anon_exclusive;
pte_t entry;

- pvmw.address = page_address_in_vma(page, vma);
+ if (WARN_ON_ONCE(folio_test_large(folio)))
+ return err;
+
+ pvmw.address = page_address_in_vma(&folio->page, vma);
if (pvmw.address == -EFAULT)
goto out;

- BUG_ON(PageTransCompound(page));
-
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, pvmw.address,
pvmw.address + PAGE_SIZE);
mmu_notifier_invalidate_range_start(&range);
@@ -1315,12 +1316,12 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
goto out_unlock;

- anon_exclusive = PageAnonExclusive(page);
+ anon_exclusive = PageAnonExclusive(&folio->page);
entry = ptep_get(pvmw.pte);
if (pte_write(entry) || pte_dirty(entry) ||
anon_exclusive || mm_tlb_flush_pending(mm)) {
- swapped = PageSwapCache(page);
- flush_cache_page(vma, pvmw.address, page_to_pfn(page));
+ swapped = folio_test_swapcache(folio);
+ flush_cache_page(vma, pvmw.address, folio_pfn(folio));
/*
* Ok this is tricky, when get_user_pages_fast() run it doesn't
* take any lock, therefore the check that we are going to make
@@ -1340,20 +1341,20 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
* Check that no O_DIRECT or similar I/O is in progress on the
* page
*/
- if (page_mapcount(page) + 1 + swapped != page_count(page)) {
+ if (folio_mapcount(folio) + 1 + swapped != folio_ref_count(folio)) {
set_pte_at(mm, pvmw.address, pvmw.pte, entry);
goto out_unlock;
}

/* See folio_try_share_anon_rmap_pte(): clear PTE first. */
if (anon_exclusive &&
- folio_try_share_anon_rmap_pte(page_folio(page), page)) {
+ folio_try_share_anon_rmap_pte(folio, &folio->page)) {
set_pte_at(mm, pvmw.address, pvmw.pte, entry);
goto out_unlock;
}

if (pte_dirty(entry))
- set_page_dirty(page);
+ folio_mark_dirty(folio);
entry = pte_mkclean(entry);

if (pte_write(entry))
@@ -1519,7 +1520,7 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
* ptes are necessarily already write-protected. But in either
* case, we need to lock and check page_count is not raised.
*/
- if (write_protect_page(vma, page, &orig_pte) == 0) {
+ if (write_protect_page(vma, page_folio(page), &orig_pte) == 0) {
if (!kpage) {
/*
* While we hold page lock, upgrade page from
--
2.43.0