linux-kernel - [PATCH v3 1/8] mm: memcontrol: fix page charging in page replacement

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210417043538.9793-2-songmuchun@bytedance.com>
Date:   Sat, 17 Apr 2021 12:35:31 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     guro@...com, hannes@...xchg.org, mhocko@...nel.org,
        akpm@...ux-foundation.org, shakeelb@...gle.com,
        vdavydov.dev@...il.com
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        duanxiongchun@...edance.com,
        Muchun Song <songmuchun@...edance.com>,
        Michal Hocko <mhocko@...e.com>
Subject: [PATCH v3 1/8] mm: memcontrol: fix page charging in page replacement

The pages aren't accounted at the root level, so do not charge the page
to the root memcg in page replacement. Although we do not display the
value (mem_cgroup_usage) so there shouldn't be any actual problem, but
there is a WARN_ON_ONCE in the page_counter_cancel(). Who knows if it
will trigger? So it is better to fix it.

Signed-off-by: Muchun Song <songmuchun@...edance.com>
Acked-by: Johannes Weiner <hannes@...xchg.org>
Reviewed-by: Shakeel Butt <shakeelb@...gle.com>
Acked-by: Roman Gushchin <guro@...com>
Acked-by: Michal Hocko <mhocko@...e.com>
---
 mm/memcontrol.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 64ada9e650a5..f229de925aa5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6806,9 +6806,11 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
 	/* Force-charge the new page. The old one will be freed soon */
 	nr_pages = thp_nr_pages(newpage);
 
-	page_counter_charge(&memcg->memory, nr_pages);
-	if (do_memsw_account())
-		page_counter_charge(&memcg->memsw, nr_pages);
+	if (!mem_cgroup_is_root(memcg)) {
+		page_counter_charge(&memcg->memory, nr_pages);
+		if (do_memsw_account())
+			page_counter_charge(&memcg->memsw, nr_pages);
+	}
 
 	css_get(&memcg->css);
 	commit_charge(newpage, memcg);
-- 
2.11.0