From: Baolin Wang <baolin.wang@linux.alibaba.com> mainline inclusion from mainline-v6.12-rc1 commit d6b8f296e8d74d685627fd746558745c13b8bd32 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAXCD2 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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/9ea49262308de28957596cc6e8edc2d3a4f54659.172414060... 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> Signed-off-by: Nanyong Sun <sunnanyong@huawei.com> --- mm/khugepaged.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 007684e8b888..b757299dfdc8 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2002,9 +2002,9 @@ 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 @@ -2012,7 +2012,7 @@ 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); @@ -2195,7 +2195,7 @@ 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; -- 2.33.0