From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shakeel Butt Subject: Re: [PATCH 1/4] memcg: enable accounting for large allocations in mem_cgroup_css_alloc Date: Fri, 20 May 2022 01:07:07 +0000 Message-ID: <20220520010707.77z5blxpbsddwmyo@google.com> References: <212f1b74-7d4e-29f2-9e92-2a1820beff61@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=G6gtvqYNjnVwht1zFDxId2+CvU+SMvS0Nm0E4p7o9cM=; b=Gq0rw+MrvLWVPrWEBXryZB1jQV/V1G9kqtZ5HVH9URkE6LQh50hBnHJMNqkGngRE1B OKQFxrvMTob/C1c6Prc225WuKjE8WCTLx3fHin7rlnzNSeIOtlGLTu74nl6iciYuNa6V wKGClUZev9JgvVbePXUNUNBu7Uz1/J49jE9sWsl47yg7HwP0TiOqv882QwVKD+FEXZY5 VRHfGsaPeQ8uLVWv02vR138ZcXZ+G+eh5CxwWdQnlEieVAYcg1VZgbsIj+VW85zoNOBM wo1vIABj/7CfTuXAAnloVwGNjfYF36gl6mrEArXq+HVLQCpFYG1ejzHnmXk3KpUV9HEj Th3w== In-Reply-To: <212f1b74-7d4e-29f2-9e92-2a1820beff61-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org> List-ID: Content-Transfer-Encoding: 7bit To: Vasily Averin Cc: Roman Gushchin , Michal =?utf-8?Q?Koutn=C3=BD?= , kernel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vlastimil Babka , Michal Hocko , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Fri, May 13, 2022 at 06:51:41PM +0300, Vasily Averin wrote: > cgroup mkdir can be misused inside memcg limited container. It can allocate > a lot of host memory without memcg accounting, cause global memory shortage > and force OOM to kill random host process. > > Below [1] is result of mkdir /sys/fs/cgroup/test tracing on VM with 4 cpus > > number bytes $1*$2 sum note call_site > of alloc > allocs > ------------------------------------------------------------ > 1 14448 14448 14448 = percpu_alloc_percpu: > 1 8192 8192 22640 (mem_cgroup_css_alloc+0x54) > 49 128 6272 28912 (__kernfs_new_node+0x4e) > 49 96 4704 33616 (simple_xattr_alloc+0x2c) > 49 88 4312 37928 (__kernfs_iattrs+0x56) > 1 4096 4096 42024 (cgroup_mkdir+0xc7) > 1 3840 3840 45864 = percpu_alloc_percpu: > 4 512 2048 47912 (alloc_fair_sched_group+0x166) > 4 512 2048 49960 (alloc_fair_sched_group+0x139) > 1 2048 2048 52008 (mem_cgroup_css_alloc+0x109) > [smaller objects skipped] > --- > Total 61728 > > '=' -- accounted allocations > > This patch enabled accounting for one of the main memory hogs in this > experiment: allocation which are called inside mem_cgroup_css_alloc() > > Signed-off-by: Vasily Averin > Link: [1] https://lore.kernel.org/all/1aa4cd22-fcb6-0e8d-a1c6-23661d618864-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org/ > Acked-by: Shakeel Butt