From: Baolin Wang baolin.wang@linux.alibaba.com
mainline inclusion from mainline-v6.11-rc2 commit 4cbf320b1500fe64fcef8c96ed74dfc1ae2c9e2c category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAIHPC
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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/07433b0f16a152bffb8cee34934a5c040e8e2ad6.172240407... Fixes: e7a2ab7b3bb5 ("mm: shmem: add mTHP support for anonymous shmem") Signed-off-by: Baolin Wang baolin.wang@linux.alibaba.com Acked-by: David Hildenbrand david@redhat.com Cc: Barry Song 21cnbao@gmail.com Cc: Gavin Shan gshan@redhat.com Cc: Hugh Dickins hughd@google.com Cc: Lance Yang ioworker0@gmail.com Cc: Matthew Wilcox willy@infradead.org Cc: Ryan Roberts ryan.roberts@arm.com Cc: Zi Yan ziy@nvidia.com Cc: Barry Song baohua@kernel.org Cc: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/shmem.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c index f579367c5968..69593d2b1566 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1698,6 +1698,7 @@ 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;
@@ -1709,9 +1710,9 @@ 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); }