From 4cbf320b1500fe64fcef8c96ed74dfc1ae2c9e2c Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Wed, 31 Jul 2024 13:46:20 +0800 Subject: mm: shmem: fix incorrect aligned index when checking conflicts In the shmem_suitable_orders() function, xa_find() is used to check for conflicts in the pagecache to select suitable huge orders. However, when checking each huge order in every loop, the aligned index is calculated from the previous iteration, which may cause suitable huge orders to be missed. We should use the original index each time in the loop to calculate a new aligned index for checking conflicts to avoid this issue. Link: https://lkml.kernel.org/r/07433b0f16a152bffb8cee34934a5c040e8e2ad6.1722404078.git.baolin.wang@linux.alibaba.com Fixes: e7a2ab7b3bb5 ("mm: shmem: add mTHP support for anonymous shmem") Signed-off-by: Baolin Wang Acked-by: David Hildenbrand Cc: Barry Song <21cnbao@gmail.com> Cc: Gavin Shan Cc: Hugh Dickins Cc: Lance Yang Cc: Matthew Wilcox Cc: Ryan Roberts Cc: Zi Yan Cc: Barry Song Cc: Kefeng Wang Signed-off-by: Andrew Morton --- mm/shmem.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index b5be73b04329..5a77acf6ac6a 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1681,6 +1681,7 @@ static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault unsigned long orders) { struct vm_area_struct *vma = vmf->vma; + pgoff_t aligned_index; unsigned long pages; int order; @@ -1692,9 +1693,9 @@ static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault order = highest_order(orders); while (orders) { pages = 1UL << order; - index = round_down(index, pages); - if (!xa_find(&mapping->i_pages, &index, - index + pages - 1, XA_PRESENT)) + aligned_index = round_down(index, pages); + if (!xa_find(&mapping->i_pages, &aligned_index, + aligned_index + pages - 1, XA_PRESENT)) break; order = next_order(&orders, order); } -- cgit v1.2.3