From: Chengming Zhou <chengming.zhou@linux.dev> stable inclusion from stable-v6.6.34 commit 0a82b46a0172dae696b04999f42b5c5697611b7f category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAD6H2 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 730cdc2c72c6905a2eda2fccbbf67dcef1206590 upstream. Patch series "mm/ksm: fix some accounting problems", v3. We encountered some abnormal ksm_pages_scanned and ksm_zero_pages during some random tests. 1. ksm_pages_scanned unchanged even ksmd scanning has progress. 2. ksm_zero_pages maybe -1 in some rare cases. This patch (of 2): During testing, I found ksm_pages_scanned is unchanged although the scan_get_next_rmap_item() did return valid rmap_item that is not NULL. The reason is the scan_get_next_rmap_item() will return NULL after a full scan, so ksm_do_scan() just return without accounting of the ksm_pages_scanned. Fix it by just putting ksm_pages_scanned accounting in that loop, and it will be accounted more timely if that loop would last for a long time. Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-0-34bb358fdc13@linux.d... Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-1-34bb358fdc13@linux.d... Fixes: b348b5fe2b5f ("mm/ksm: add pages scanned metric") Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: xu xin <xu.xin16@zte.com.cn> 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: Yang Yang <yang.yang29@zte.com.cn> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Wang Hai <wanghai38@huawei.com> --- mm/ksm.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/ksm.c b/mm/ksm.c index 09411079262b..e0a2f9d58db3 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2491,18 +2491,16 @@ static void ksm_do_scan(unsigned int scan_npages) { struct ksm_rmap_item *rmap_item; struct page *page; - unsigned int npages = scan_npages; - while (npages-- && likely(!freezing(current))) { + while (scan_npages-- && likely(!freezing(current))) { cond_resched(); rmap_item = scan_get_next_rmap_item(&page); if (!rmap_item) return; cmp_and_merge_page(page, rmap_item); put_page(page); + ksm_pages_scanned++; } - - ksm_pages_scanned += scan_npages - npages; } static int ksmd_should_run(void) -- 2.17.1