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| author |   Chengming Zhou <chengming.zhou@linux.dev> | 2024-05-28 13:15:22 +0800 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2024-06-05 19:19:26 -0700 |
| commit | c2dc78b86e0821ecf9a9d0c35dba2618279a5bb6 (patch) | |
| tree | b023d4ec8ba10a50829dae578c56b2edf698f4ee /include/linux/mm_types.h | |
| parent | mm/ksm: fix ksm_pages_scanned accounting (diff) | |
| download | wireguard-linux-c2dc78b86e0821ecf9a9d0c35dba2618279a5bb6.tar.xz wireguard-linux-c2dc78b86e0821ecf9a9d0c35dba2618279a5bb6.zip | |
mm/ksm: fix ksm_zero_pages accounting
We normally ksm_zero_pages++ in ksmd when page is merged with zero page,
but ksm_zero_pages-- is done from page tables side, where there is no any
accessing protection of ksm_zero_pages.
So we can read very exceptional value of ksm_zero_pages in rare cases,
such as -1, which is very confusing to users.
Fix it by changing to use atomic_long_t, and the same case with the
mm->ksm_zero_pages.
Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-2-34bb358fdc13@linux.dev
Fixes: e2942062e01d ("ksm: count all zero pages placed by KSM")
Fixes: 6080d19f0704 ("ksm: add ksm zero pages for each process")
Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Stefan Roesch <shr@devkernel.io>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/mm_types.h')
| -rw-r--r-- | include/linux/mm_types.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 24323c7d0bd4..af3a0256fa93 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -985,7 +985,7 @@ struct mm_struct { * Represent how many empty pages are merged with kernel zero * pages when enabling KSM use_zero_pages. */ - unsigned long ksm_zero_pages; + atomic_long_t ksm_zero_pages; #endif /* CONFIG_KSM */ #ifdef CONFIG_LRU_GEN_WALKS_MMU struct { |