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From:   Vasily Averin <vvs@virtuozzo.com>
Subject: [PATCH v7 07/10] memcg: enable accounting for signals
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     cgroups@vger.kernel.org, Michal Hocko <mhocko@kernel.org>,
        Shakeel Butt <shakeelb@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Roman Gushchin <guro@fb.com>, Jens Axboe <axboe@kernel.dk>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Oleg Nesterov <oleg@redhat.com>, linux-kernel@vger.kernel.org
References: <6f21a0e0-bd36-b6be-1ffa-0dc86c06c470@virtuozzo.com>
 <cover.1627362057.git.vvs@virtuozzo.com>
Message-ID: <e34e958c-e785-712e-a62a-2c7b66c646c7@virtuozzo.com>
Date:   Tue, 27 Jul 2021 08:34:01 +0300
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When a user send a signal to any another processes it forces the kernel
to allocate memory for 'struct sigqueue' objects. The number of signals
is limited by RLIMIT_SIGPENDING resource limit, but even the default
settings allow each user to consume up to several megabytes of memory.

It makes sense to account for these allocations to restrict the host's
memory consumption from inside the memcg-limited container.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
---
 kernel/signal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index a3229ad..8921c4a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -4663,7 +4663,7 @@ void __init signals_init(void)
 {
 	siginfo_buildtime_checks();
 
-	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
+	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC | SLAB_ACCOUNT);
 }
 
 #ifdef CONFIG_KGDB_KDB
-- 
1.8.3.1