The patch titled
Subject: mm/ksm: fix ksm_pages_scanned accounting
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-ksm-fix-ksm_pages_scanned-accounting.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-ksm-fix-ksm_pages_scanned-accounting.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Chengming Zhou <chengming.zhou@xxxxxxxxx>
Subject: mm/ksm: fix ksm_pages_scanned accounting
Date: Tue, 28 May 2024 13:15:21 +0800
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>
---
mm/ksm.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/mm/ksm.c~mm-ksm-fix-ksm_pages_scanned-accounting
+++ a/mm/ksm.c
@@ -2753,18 +2753,16 @@ 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)
_
Patches currently in -mm which might be from chengming.zhou@xxxxxxxxx are
mm-ksm-fix-ksm_pages_scanned-accounting.patch
mm-ksm-fix-ksm_zero_pages-accounting.patch
