The patch titled
Subject: mm: shmem: fix incorrect aligned index when checking conflicts
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-shmem-fix-incorrect-aligned-index-when-checking-conflicts.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-fix-incorrect-aligned-index-when-checking-conflicts.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Subject: mm: shmem: fix incorrect aligned index when checking conflicts
Date: Wed, 31 Jul 2024 13:46:20 +0800
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@xxxxxxxxxxxxxxxxx
Fixes: e7a2ab7b3bb5 ("mm: shmem: add mTHP support for anonymous shmem")
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Barry Song <21cnbao@xxxxxxxxx>
Cc: Gavin Shan <gshan@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Lance Yang <ioworker0@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Barry Song <baohua@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/mm/shmem.c~mm-shmem-fix-incorrect-aligned-index-when-checking-conflicts
+++ a/mm/shmem.c
@@ -1681,6 +1681,7 @@ static unsigned long shmem_suitable_orde
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_orde
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);
}
_
Patches currently in -mm which might be from baolin.wang@xxxxxxxxxxxxxxxxx are
mm-shmem-avoid-allocating-huge-pages-larger-than-max_pagecache_order-for-shmem.patch
mm-shmem-avoid-allocating-huge-pages-larger-than-max_pagecache_order-for-shmem-fix.patch
mm-shmem-fix-incorrect-aligned-index-when-checking-conflicts.patch
mm-shmem-simplify-the-suitable-huge-orders-validation-for-tmpfs.patch
mm-shmem-rename-shmem_is_huge-to-shmem_huge_global_enabled.patch
mm-shmem-move-shmem_huge_global_enabled-into-shmem_allowable_huge_orders.patch
