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| author | David Stevens <stevensd@chromium.org> | 2023-06-07 07:31:35 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-06-19 22:19:32 +0200 |
| commit | c8a8f3b4a95ace7683b615ad9c9aa0eac59013ae (patch) | |
| tree | 5e898bb9a54517d556e8e68d9123c5deb1627a92 /mm/khugepaged.c | |
| parent | memfd: check for non-NULL file_seals in memfd_create() syscall (diff) | |
| download | linux-c8a8f3b4a95ace7683b615ad9c9aa0eac59013ae.tar.xz linux-c8a8f3b4a95ace7683b615ad9c9aa0eac59013ae.zip | |
mm/khugepaged: fix iteration in collapse_file
Remove an unnecessary call to xas_set(index) when iterating over the
target range in collapse_file. The extra call to xas_set reset the xas
cursor to the top of the tree, causing the xas_next call on the next
iteration to walk the tree to index instead of advancing to index+1. This
returned the same page again, which would cause collapse_file to fail
because the page is already locked.
This bug was hidden when CONFIG_DEBUG_VM was set. When that config was
used, the xas_load in a subsequent VM_BUG_ON assert would walk xas from
the top of the tree to index, causing the xas_next call on the next loop
iteration to advance the cursor as expected.
Link: https://lkml.kernel.org/r/20230607053135.2087354-1-stevensd@google.com
Fixes: a2e17cc2efc7 ("mm/khugepaged: maintain page cache uptodate flag")
Signed-off-by: David Stevens <stevensd@chromium.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Kirill A . Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/khugepaged.c')
| -rw-r--r-- | mm/khugepaged.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 6b9d39d65b73..2d0d58fb4e7f 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2070,7 +2070,6 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, TTU_IGNORE_MLOCK | TTU_BATCH_FLUSH); xas_lock_irq(&xas); - xas_set(&xas, index); VM_BUG_ON_PAGE(page != xas_load(&xas), page); |