6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chengming Zhou <chengming.zhou@xxxxxxxxx> 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@xxxxxxxxx Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-1-34bb358fdc13@xxxxxxxxx Fixes: b348b5fe2b5f ("mm/ksm: add pages scanned metric") Signed-off-by: Chengming Zhou <chengming.zhou@xxxxxxxxx> Acked-by: David Hildenbrand <david@xxxxxxxxxx> Reviewed-by: xu xin <xu.xin16@xxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Ran Xiaokai <ran.xiaokai@xxxxxxxxxx> Cc: Stefan Roesch <shr@xxxxxxxxxxxx> Cc: Yang Yang <yang.yang29@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/ksm.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2486,18 +2486,16 @@ static void ksm_do_scan(unsigned int sca { 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)
