From: Baolin Wang baolin.wang@linux.alibaba.com
mainline inclusion from mainline-v6.12-rc4 commit d60fcaf00d752c52fdf566d4184e6d04d9d08879 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...
--------------------------------
Khugepaged already supports collapsing file large folios (including shmem mTHP) by commit 7de856ffd007 ("mm: khugepaged: support shmem mTHP collapse"), and the control parameters in khugepaged: 'khugepaged_max_ptes_swap' and 'khugepaged_max_ptes_none', still compare based on PTE granularity to determine whether a file collapse is needed. However, the statistics for 'present' and 'swap' in hpage_collapse_scan_file() do not take into account the large folios, which may lead to incorrect judgments regarding the khugepaged_max_ptes_swap/none parameters, resulting in unnecessary file collapses.
To fix this issue, take into account the large folios' statistics for 'present' and 'swap' variables in the hpage_collapse_scan_file().
Link: https://lkml.kernel.org/r/c76305d96d12d030a1a346b50503d148364246d2.172890139... Fixes: 7de856ffd007 ("mm: khugepaged: support shmem mTHP collapse") Signed-off-by: Baolin Wang baolin.wang@linux.alibaba.com Acked-by: David Hildenbrand david@redhat.com Reviewed-by: Barry Song baohua@kernel.org Reviewed-by: Zi Yan ziy@nvidia.com Reviewed-by: Yang Shi shy828301@gmail.com Cc: Hugh Dickins hughd@google.com Cc: Matthew Wilcox willy@infradead.org Cc: Ryan Roberts ryan.roberts@arm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Nanyong Sun sunnanyong@huawei.com --- mm/khugepaged.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 574aacbca7e7..7f87636c530e 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2266,7 +2266,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, continue;
if (xa_is_value(folio)) { - ++swap; + swap += 1 << xas_get_order(&xas); if (cc->is_khugepaged && swap > khugepaged_max_ptes_swap) { result = SCAN_EXCEED_SWAP_PTE; @@ -2318,7 +2318,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, * is just too costly... */
- present++; + present += folio_nr_pages(folio);
if (need_resched()) { xas_pause(&xas);