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From: Roman Gushchin To: Tejun Heo Cc: Vasily Averin , Michal =?iso-8859-1?Q?Koutn=FD?= , Shakeel Butt , Michal Hocko , Zefan Li , Johannes Weiner , kernel@openvz.org, linux-kernel@vger.kernel.org, Andrew Morton , linux-mm@kvack.org, Vlastimil Babka , Muchun Song , cgroups@vger.kernel.org Subject: Re: [PATCH cgroup] cgroup: set the correct return code if hierarchy limits are reached Message-ID: References: <186d5b5b-a082-3814-9963-bf57dfe08511@openvz.org> <17916824-ba97-68ba-8166-9402d5f4440c@openvz.org> <20220628091648.GA12249@blackbody.suse.cz> <525a3eea-8431-64ad-e464-5503f3297722@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656643365; a=rsa-sha256; cv=none; b=frvnbcRhZqsSgp825aaBv3gb8jrT3fTP9Ts4KKR+OHrJ7RDJaegsTg7UXXGXlrVn63FyHs a0r970A1R4tcEQNvQUFalV7wX6p0y3s+6e51Mi+nPtNjQVCdXQHb9mq8P/mx5Jx9VuLrfp 84KMefI8/43YrzH0DpxjrJsuWUxiQfo= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Scqzngmd; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf08.hostedemail.com: domain of roman.gushchin@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656643365; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=pMVELDaA6mcFkDFllRvcL5kIjjxBxBLDIIVIdn97dz4=; b=INNHpcZj9zBHcTU4LLP6TPUxEBhbk2YpY5KpJZ5RZ1FzIce9y94grrPl0E2KJ6b3AFvMJU ueIAFIPLfO41X8o2DWr6H7wE2utQYx+TizBJRKmbWc4xIJvdG4EJ+E1Btfxy6bu4ht8DfM CB9vVmnVbT3rkdb2b/VEGj/+ckjb1P0= X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 12FA2160020 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Scqzngmd; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf08.hostedemail.com: domain of roman.gushchin@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev X-Rspam-User: X-Stat-Signature: beihnfo387jdartqtenseaspwcds6r14 X-HE-Tag: 1656643364-82441 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jun 30, 2022 at 04:25:57AM +0900, Tejun Heo wrote: > On Wed, Jun 29, 2022 at 09:13:02AM +0300, Vasily Averin wrote: > > I experimented on fedora36 node with LXC and centos stream 9 container. > > and I did not noticed any critical systemd troubles with original -EAGAIN. > > When cgroup's limit is reached systemd cannot start new services, > > for example lxc-attach generates following output: > > > > [root@fc34-vvs ~]# lxc-attach c9s > > lxc-attach: c9s: cgroups/cgfsng.c: cgroup_attach_leaf: 2084 Resource temporarily unavailable - Failed to create leaf cgroup ".lxc" > > lxc-attach: c9s: cgroups/cgfsng.c: __cgroup_attach_many: 3517 Resource temporarily unavailable - Failed to attach to cgroup fd 11 > > lxc-attach: c9s: attach.c: lxc_attach: 1679 Resource temporarily unavailable - Failed to attach cgroup > > lxc-attach: c9s: attach.c: do_attach: 1237 No data available - Failed to receive lsm label fd > > lxc-attach: c9s: attach.c: do_attach: 1375 Failed to attach to container > > > > I did not found any loop in userspace caused by EAGAIN. > > Messages looks unclear, however situation with the patched kernel is not much better: > > > > [root@fc34-vvs ~]# lxc-attach c9s > > lxc-attach: c9s: cgroups/cgfsng.c: cgroup_attach_leaf: 2084 No space left on device - Failed to create leaf cgroup ".lxc" > > lxc-attach: c9s: cgroups/cgfsng.c: __cgroup_attach_many: 3517 No space left on device - Failed to attach to cgroup fd 11 > > lxc-attach: c9s: attach.c: lxc_attach: 1679 No space left on device - Failed to attach cgroup > > lxc-attach: c9s: attach.c: do_attach: 1237 No data available - Failed to receive lsm label fd > > lxc-attach: c9s: attach.c: do_attach: 1375 Failed to attach to container > > I'd say "resource temporarily unavailable" is better fitting than "no > space left on device" +1 Thanks!