From c2dc78b86e0821ecf9a9d0c35dba2618279a5bb6 Mon Sep 17 00:00:00 2001 From: Chengming Zhou Date: Tue, 28 May 2024 13:15:22 +0800 Subject: 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 Acked-by: David Hildenbrand Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Ran Xiaokai Cc: Stefan Roesch Cc: xu xin Cc: Yang Yang Cc: Signed-off-by: Andrew Morton --- fs/proc/base.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/proc/base.c b/fs/proc/base.c index 18550c071d71..72a1acd03675 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3214,7 +3214,7 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns, mm = get_task_mm(task); if (mm) { seq_printf(m, "ksm_rmap_items %lu\n", mm->ksm_rmap_items); - seq_printf(m, "ksm_zero_pages %lu\n", mm->ksm_zero_pages); + seq_printf(m, "ksm_zero_pages %ld\n", mm_ksm_zero_pages(mm)); seq_printf(m, "ksm_merging_pages %lu\n", mm->ksm_merging_pages); seq_printf(m, "ksm_process_profit %ld\n", ksm_process_profit(mm)); mmput(mm); -- cgit v1.2.3