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From: Roman Gushchin To: Michal Hocko Cc: Andrew Morton , Johannes Weiner , Shakeel Butt , Muchun Song , linux-mm@kvack.org Subject: Re: [PATCH] memcg: drop kmem.limit_in_bytes Message-ID: References: <20230704115240.14672-1-mhocko@kernel.org> <20230705134434.GA156754@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 376B9160010 X-Stat-Signature: xsmah59diaejgfhpzckzjkqzsknnowij X-Rspam-User: X-HE-Tag: 1688748029-690422 X-HE-Meta: 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 jjcQA+xb 1wxu6yPH6dmi2wnkDgthpZi1haFTunAqtyJCllaRp7g9DzKA1K/jG9TDsubixUE83Ub3O50glRo6CSpOOOWHdBvEjyCA8ALiDgRoxwa5UTPfGjDmBHExvuBUbqvVx+6IuVP8tdylDCVcSbN1UCVV2Yb7dxVua/iesVblIaeFlGwBq155MtO0BVIIMQomMVjFoNvSlNJVxNkMQd3gQGMt8S2I/nxe/N8gASadArNojjBInlFUMt3aMnVu5GKw4HBlCo5N7dbClG6rQhjQ= 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 Fri, Jul 07, 2023 at 09:07:47AM +0200, Michal Hocko wrote: > On Wed 05-07-23 09:44:34, Johannes Weiner wrote: > [...] > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > index 4b27e245a055..a0d3ed8d02e2 100644 > > > --- a/mm/memcontrol.c > > > +++ b/mm/memcontrol.c > > > @@ -3750,9 +3750,6 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, > > > case _MEMSWAP: > > > counter = &memcg->memsw; > > > break; > > > - case _KMEM: > > > - counter = &memcg->kmem; > > > - break; > > > case _TCP: > > > counter = &memcg->tcpmem; > > > break; > > > > This case is still needed for the remaining kmem files: > > > > { > > .name = "kmem.usage_in_bytes", > > .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE), > > .read_u64 = mem_cgroup_read_u64, > > }, > > { > > .name = "kmem.failcnt", > > .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT), > > .write = mem_cgroup_reset, > > .read_u64 = mem_cgroup_read_u64, > > }, > > { > > .name = "kmem.max_usage_in_bytes", > > .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE), > > .write = mem_cgroup_reset, > > .read_u64 = mem_cgroup_read_u64, > > }, > > > > otherwise they BUG() when reading. > > > > Without this hunk, the patch looks good to me. > > You are right! Thanks. The updated patch below. Andrew could you replace > by this version please? > --- > From b1bbc63b6baff9c5aaf30393cec29112b3abca25 Mon Sep 17 00:00:00 2001 > From: Michal Hocko > Date: Tue, 4 Jul 2023 13:38:11 +0200 > Subject: [PATCH] memcg: drop kmem.limit_in_bytes > > kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been > deprecated since 58056f77502f ("memcg, kmem: further deprecate > kmem.limit_in_bytes") merged in 5.16. We haven't heard about any > serious users since then but it seems that the mere presence of the file > is causing more harm thatn good. We (SUSE) have had several bug reports > from customers where Docker based containers started to fail because a > write to kmem.limit_in_bytes has failed. > > This was unexpected because runc code only expects ENOENT (kmem > disabled) or EBUSY (tasks already running within cgroup). So a new error > code was unexpected and the whole container startup failed. This has > been later addressed by > https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380 > so current Docker runtimes do not suffer from the problem anymore. There > are still older version of Docker in use and likely hard to get rid of > completely. > > Address this by wiping out the file completely and effectively get back > to pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration. > > I would recommend backporting to stable trees which have picked up > 58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes"). > > Cc: stable > Signed-off-by: Michal Hocko Acked-by: Roman Gushchin Thanks!