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From: Michal Hocko <mhocko@suse.com>
To: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	cgroups@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/memcg: remove useless check on page->mem_cgroup
Date: Mon, 10 Aug 2020 11:53:10 +0200	[thread overview]
Message-ID: <20200810095310.GD4773@dhcp22.suse.cz> (raw)
In-Reply-To: <20200810095201.GC4773@dhcp22.suse.cz>

On Mon 10-08-20 11:52:02, Michal Hocko wrote:
> On Wed 05-08-20 21:02:30, Alex Shi wrote:
> > 
> > 
> > 在 2020/8/5 下午8:28, Alex Shi 写道:
> > > The last patch has a problem on define. this version could fix it.
> > > 
> > > BTW, I see some !memcg happens when MEMCG compilered but disabled by cgroup_disable
> > > 
> > > 
> > > [   94.657666] ---[ end trace f1f34bfc3b32ed2f ]---
> > > [   95.138995] anon flags: 0x5005b48008000d(locked|uptodate|dirty|swapbacked)
> > > [   95.146220] raw: 005005b48008000d dead000000000100 dead000000000122 ffff8897c7c76ad1
> > > [   95.154549] raw: 0000000000000022 0000000000000000 0000000200000000 0000000000000000
> > > [   95.162876] page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg)
> > > 
> > > 
> > 
> > The following patch may helpful.
> > 
> > >From 8bfb26a2e37e08dc61d20212bcfa5812a367ba94 Mon Sep 17 00:00:00 2001
> > From: Alex Shi <alex.shi@linux.alibaba.com>
> > Date: Wed, 5 Aug 2020 20:32:12 +0800
> > Subject: [PATCH] mm/memcg: don't try charge swap if memcg disabled
> > 
> > If we disabled memcg by cgroup_disable=memory, the swap charges are
> > still called. Let's return from the funcs earlier and keep WARN_ON
> > monitor.
> 
> Do I get it right that this is on top of your patch to remove the memcg
> check or a preparatory work?

Sorry meant to say - add the warning rather than drop the check.

> Both are good but it would be better to
> call that out specifically for clarity (along with the warning if that
> is a follow up fix).
-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
To: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Vladimir Davydov
	<vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] mm/memcg: remove useless check on page->mem_cgroup
Date: Mon, 10 Aug 2020 11:53:10 +0200	[thread overview]
Message-ID: <20200810095310.GD4773@dhcp22.suse.cz> (raw)
In-Reply-To: <20200810095201.GC4773-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>

On Mon 10-08-20 11:52:02, Michal Hocko wrote:
> On Wed 05-08-20 21:02:30, Alex Shi wrote:
> > 
> > 
> > 在 2020/8/5 下午8:28, Alex Shi 写道:
> > > The last patch has a problem on define. this version could fix it.
> > > 
> > > BTW, I see some !memcg happens when MEMCG compilered but disabled by cgroup_disable
> > > 
> > > 
> > > [   94.657666] ---[ end trace f1f34bfc3b32ed2f ]---
> > > [   95.138995] anon flags: 0x5005b48008000d(locked|uptodate|dirty|swapbacked)
> > > [   95.146220] raw: 005005b48008000d dead000000000100 dead000000000122 ffff8897c7c76ad1
> > > [   95.154549] raw: 0000000000000022 0000000000000000 0000000200000000 0000000000000000
> > > [   95.162876] page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg)
> > > 
> > > 
> > 
> > The following patch may helpful.
> > 
> > >From 8bfb26a2e37e08dc61d20212bcfa5812a367ba94 Mon Sep 17 00:00:00 2001
> > From: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>
> > Date: Wed, 5 Aug 2020 20:32:12 +0800
> > Subject: [PATCH] mm/memcg: don't try charge swap if memcg disabled
> > 
> > If we disabled memcg by cgroup_disable=memory, the swap charges are
> > still called. Let's return from the funcs earlier and keep WARN_ON
> > monitor.
> 
> Do I get it right that this is on top of your patch to remove the memcg
> check or a preparatory work?

Sorry meant to say - add the warning rather than drop the check.

> Both are good but it would be better to
> call that out specifically for clarity (along with the warning if that
> is a follow up fix).
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2020-08-10  9:53 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31  3:34 [PATCH] mm/memcg: remove useless check on page->mem_cgroup Alex Shi
2020-07-31  3:34 ` Alex Shi
2020-07-31 15:16 ` Johannes Weiner
2020-07-31 15:16   ` Johannes Weiner
2020-08-01  3:58   ` Alex Shi
2020-08-01  3:58     ` Alex Shi
2020-08-03  8:18     ` Michal Hocko
2020-08-03  8:18       ` Michal Hocko
2020-08-04  7:35       ` Alex Shi
2020-08-04  7:35         ` Alex Shi
2020-08-05 12:28         ` Alex Shi
2020-08-05 13:02           ` Alex Shi
2020-08-08 13:22             ` Alex Shi
2020-08-08 13:22               ` Alex Shi
2020-08-08 21:43               ` Roman Gushchin
2020-08-08 21:43                 ` Roman Gushchin
2020-08-10  7:44                 ` Alex Shi
2020-08-10  7:44                   ` Alex Shi
2020-08-10  9:52             ` Michal Hocko
2020-08-10  9:52               ` Michal Hocko
2020-08-10  9:53               ` Michal Hocko [this message]
2020-08-10  9:53                 ` Michal Hocko
2020-08-10  9:55           ` Michal Hocko
2020-08-10  9:55             ` Michal Hocko
2020-08-10 12:29             ` Alex Shi
2020-08-10 12:29               ` Alex Shi

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