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mm: khugepaged: use the number of pages in the folio to check the reference count

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Use the number of pages in the folio to check the reference count as
preparation for supporting shmem mTHP collapse.

Link: https://lkml.kernel.org/r/9ea49262308de28957596cc6e8edc2d3a4f54659.1724140601.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Baolin Wang 2024-08-20 17:49:14 +08:00 committed by Andrew Morton
parent fda6d4de06
commit d6b8f296e8
1 changed files with 4 additions and 4 deletions
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8
mm/khugepaged.c
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@ -1988,9 +1988,9 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
VM_BUG_ON_FOLIO(folio != xa_load(xas.xa, index), folio);
/*
* We control three references to the folio:
* We control 2 + nr_pages references to the folio:
* - we hold a pin on it;
* - one reference from page cache;
* - nr_pages reference from page cache;
* - one from lru_isolate_folio;
* If those are the only references, then any new usage
* of the folio will have to fetch it from the page
@ -1998,7 +1998,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
* truncate, so any new usage will be blocked until we
* unlock folio after collapse/during rollback.
*/
if (folio_ref_count(folio) != 3) {
if (folio_ref_count(folio) != 2 + folio_nr_pages(folio)) {
result = SCAN_PAGE_COUNT;
xas_unlock_irq(&xas);
folio_putback_lru(folio);
@ -2181,7 +2181,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
folio_clear_active(folio);
folio_clear_unevictable(folio);
folio_unlock(folio);
folio_put_refs(folio, 3);
folio_put_refs(folio, 2 + folio_nr_pages(folio));
}
goto out;