The patch titled
Subject: mm/filemap.c: remove bogus VM_BUG_ON
has been added to the -mm tree. Its filename is
mm-remove-bogus-vm_bug_on.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-remove-bogus-vm_bug_on.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-remove-bogus-vm_bug_on.patch
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm/filemap.c: remove bogus VM_BUG_ON
It is not safe to check page->index without holding the page lock. It can
be changed if the page is moved between the swap cache and the page cache
for a shmem file, for example. There is a VM_BUG_ON below which checks
page->index is correct after taking the page lock.
Link: https://lkml.kernel.org/r/20210818144932.940640-1-willy@xxxxxxxxxxxxx
Fixes: 5c211ba29deb ("mm: add and use find_lock_entries")
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reported-by: <syzbot+c87be4f669d920c76330@xxxxxxxxxxxxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 1 -
1 file changed, 1 deletion(-)
--- a/mm/filemap.c~mm-remove-bogus-vm_bug_on
+++ a/mm/filemap.c
@@ -2038,7 +2038,6 @@ unsigned find_lock_entries(struct addres
if (!xa_is_value(page)) {
if (page->index < start)
goto put;
- VM_BUG_ON_PAGE(page->index != xas.xa_index, page);
if (page->index + thp_nr_pages(page) - 1 > end)
goto put;
if (!trylock_page(page))
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-remove-bogus-vm_bug_on.patch
mm-report-a-more-useful-address-for-reclaim-acquisition.patch
mm-mark-idle-page-tracking-as-broken.patch
avoid-a-warning-in-sparse-memory-support.patch
mm-move-kvmalloc-related-functions-to-slabh.patch
