[PATCH 09/10] mm/ksm: calc_checksum for folio

alexs
2024-06-04T04:21:58Z

From: "Alex Shi (tencent)" <alexs@kernel.org>

Let's check the whole folio for contents change, don't count it if the
folio changed.

Signed-off-by: Alex Shi (tencent) <alexs@kernel.org>
---
mm/ksm.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index b9c04ce677b9..dc2b5e6a9659 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1258,11 +1258,13 @@ static int unmerge_and_remove_all_rmap_items(void)
}
#endif /* CONFIG_SYSFS */

-static u32 calc_checksum(struct page *page)
+static u32 calc_checksum(struct folio *folio)
{
u32 checksum;
- void *addr = kmap_local_page(page);
- checksum = xxhash(addr, PAGE_SIZE, 0);
+ int nr = folio_nr_pages(folio);
+ void *addr = kmap_local_page(folio_page(folio, 0));
+
+ checksum = xxhash(addr, nr * PAGE_SIZE, 0);
kunmap_local(addr);
return checksum;
}
@@ -2369,7 +2371,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
* don't want to insert it in the unstable tree, and we don't want
* to waste our time searching for something identical to it there.
*/
- checksum = calc_checksum(page);
+ checksum = calc_checksum(folio);
if (rmap_item->oldchecksum != checksum) {
rmap_item->oldchecksum = checksum;
return;
@@ -2385,7 +2387,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
mmap_read_lock(mm);
vma = find_mergeable_vma(mm, rmap_item->address);
if (vma) {
- err = try_to_merge_one_page(vma, page_folio(page), rmap_item,
+ err = try_to_merge_one_page(vma, folio, rmap_item,
page_folio(ZERO_PAGE(rmap_item->address)));
trace_ksm_merge_one_page(
page_to_pfn(ZERO_PAGE(rmap_item->address)),
@@ -3916,7 +3918,7 @@ static int __init ksm_init(void)
int err;

/* The correct value depends on page size and endianness */
- zero_checksum = calc_checksum(ZERO_PAGE(0));
+ zero_checksum = calc_checksum(page_folio(ZERO_PAGE(0)));
/* Default to false for backwards compatibility */
ksm_use_zero_pages = false;

--
2.43.0