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From: Andrew Morton <akpm@linux-foundation.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shakeel Butt <shakeelb@google.com>, Roman Gushchin <guro@fb.com>,
	Lorenzo Stoakes <lstoakes@gmail.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	Yafang Shao <laoar.shao@gmail.com>,
	Wei Yang <richard.weiyang@gmail.com>,
	linux-kernel@vger.kernel.org,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] mm/memcg: bail out early when !memcg in mem_cgroup_lruvec
Date: Mon, 30 Nov 2020 12:19:56 -0800	[thread overview]
Message-ID: <20201130121956.d03efaa95d3112d0b91291d6@linux-foundation.org> (raw)
In-Reply-To: <67aacbba-7049-bee8-0ad4-ab4db588c841@gmail.com>

On Mon, 30 Nov 2020 22:44:11 +0300 Dmitry Osipenko <digetx@gmail.com> wrote:

> > From: Alex Shi <alex.shi@linux.alibaba.com>
> > Date: Wed, 25 Nov 2020 14:06:33 +0800
> > Subject: [PATCH v2] mm/memcg: bail out early when !memcg in mem_cgroup_lruvec
> > 
> > Sometime, we use NULL memcg in mem_cgroup_lruvec(memcg, pgdat)
> > so we could get out early in the situation to avoid useless checking.
> > 
> > Polished as Andrew Morton's suggestion.
> > 
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -610,20 +610,17 @@ mem_cgroup_nodeinfo(struct mem_cgroup *memcg, int nid)
> >  static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
> >  					       struct pglist_data *pgdat)
> >  {
> > -	struct mem_cgroup_per_node *mz;
> >  	struct lruvec *lruvec;
> >  
> > -	if (mem_cgroup_disabled()) {
> > +	if (mem_cgroup_disabled() || !memcg) {
> >  		lruvec = &pgdat->__lruvec;
> > -		goto out;
> > -	}
> > +	} else {
> > +		struct mem_cgroup_per_node *mz;
> >  
> > -	if (!memcg)
> > -		memcg = root_mem_cgroup;
> > +		mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id);
> > +		lruvec = &mz->lruvec;
> > +	}
> >  
> > -	mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id);
> > -	lruvec = &mz->lruvec;
> > -out:
> >  	/*
> >  	 * Since a node can be onlined after the mem_cgroup was created,
> >  	 * we have to be prepared to initialize lruvec->pgdat here;
> > 
> 
> Hi,
> 
> This patch causes a hard lock on one of my ARM32 devices using today's
> linux-next, please fix.

Thanks.

This is unexpected.  I assume you've confirmed that reverting this
change from linux-next fixes things?



WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	Lorenzo Stoakes <lstoakes@gmail.com>,
	linux-kernel@vger.kernel.org,
	Wei Yang <richard.weiyang@gmail.com>,
	Yafang Shao <laoar.shao@gmail.com>,
	Shakeel Butt <shakeelb@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	Alex Shi <alex.shi@linux.alibaba.com>,
	Roman Gushchin <guro@fb.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] mm/memcg: bail out early when !memcg in mem_cgroup_lruvec
Date: Mon, 30 Nov 2020 12:19:56 -0800	[thread overview]
Message-ID: <20201130121956.d03efaa95d3112d0b91291d6@linux-foundation.org> (raw)
In-Reply-To: <67aacbba-7049-bee8-0ad4-ab4db588c841@gmail.com>

On Mon, 30 Nov 2020 22:44:11 +0300 Dmitry Osipenko <digetx@gmail.com> wrote:

> > From: Alex Shi <alex.shi@linux.alibaba.com>
> > Date: Wed, 25 Nov 2020 14:06:33 +0800
> > Subject: [PATCH v2] mm/memcg: bail out early when !memcg in mem_cgroup_lruvec
> > 
> > Sometime, we use NULL memcg in mem_cgroup_lruvec(memcg, pgdat)
> > so we could get out early in the situation to avoid useless checking.
> > 
> > Polished as Andrew Morton's suggestion.
> > 
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -610,20 +610,17 @@ mem_cgroup_nodeinfo(struct mem_cgroup *memcg, int nid)
> >  static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
> >  					       struct pglist_data *pgdat)
> >  {
> > -	struct mem_cgroup_per_node *mz;
> >  	struct lruvec *lruvec;
> >  
> > -	if (mem_cgroup_disabled()) {
> > +	if (mem_cgroup_disabled() || !memcg) {
> >  		lruvec = &pgdat->__lruvec;
> > -		goto out;
> > -	}
> > +	} else {
> > +		struct mem_cgroup_per_node *mz;
> >  
> > -	if (!memcg)
> > -		memcg = root_mem_cgroup;
> > +		mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id);
> > +		lruvec = &mz->lruvec;
> > +	}
> >  
> > -	mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id);
> > -	lruvec = &mz->lruvec;
> > -out:
> >  	/*
> >  	 * Since a node can be onlined after the mem_cgroup was created,
> >  	 * we have to be prepared to initialize lruvec->pgdat here;
> > 
> 
> Hi,
> 
> This patch causes a hard lock on one of my ARM32 devices using today's
> linux-next, please fix.

Thanks.

This is unexpected.  I assume you've confirmed that reverting this
change from linux-next fixes things?



_______________________________________________
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  reply	other threads:[~2020-11-30 20:20 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-27  3:08 [PATCH] mm/memcg: bail out early when !memcg in mem_cgroup_lruvec Alex Shi
2020-11-28  4:02 ` Andrew Morton
2020-11-29  4:43   ` Alex Shi
2020-11-30 19:44     ` Dmitry Osipenko
2020-11-30 19:44       ` Dmitry Osipenko
2020-11-30 20:19       ` Andrew Morton [this message]
2020-11-30 20:19         ` Andrew Morton

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