From: Michal Hocko <mhocko@kernel.org>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Tejun Heo <tj@kernel.org>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH] mm: memcontrol: do not recurse in direct reclaim
Date: Tue, 25 Oct 2016 17:07:59 +0200 [thread overview]
Message-ID: <20161025150758.GN31137@dhcp22.suse.cz> (raw)
In-Reply-To: <20161025150142.GA31081@cmpxchg.org>
On Tue 25-10-16 11:01:42, Johannes Weiner wrote:
> On Tue, Oct 25, 2016 at 04:45:44PM +0200, Michal Hocko wrote:
> > On Tue 25-10-16 10:10:50, Johannes Weiner wrote:
> > > Like other direct reclaimers, mark tasks in memcg reclaim PF_MEMALLOC
> > > to avoid recursing into any other form of direct reclaim. Then let
> > > recursive charges from PF_MEMALLOC contexts bypass the cgroup limit.
> >
> > Should we mark this for stable (up to 4.5) which changed the out-out to
> > opt-in?
>
> Yes, good point.
>
> Internally, we're pulling it into our 4.6 tree as well. The commit
> that fixes the particular bug we encountered in btrfs is a9bb7e620efd
> ("memcg: only account kmem allocations marked as __GFP_ACCOUNT") in
> 4.5+, so you could argue that we don't need the backport in kernels
> with this commit. And I'm not aware of other manifestations of this
> problem. But the unbounded recursion hole is still there, technically,
> so we might just want to put it into all stable kernels and be safe.
>
> So either
>
> Cc: <stable@vger.kernel.org> # up to and including 4.5
As the patch was released in 4.5 it shouldn't be needed in 4.5 stable
tree but
> or, and I'm leaning toward that, simply
>
> Cc: <stable@vger.kernel.org>
this sounds less confusing I guess.
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2016-10-25 15:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-24 20:30 [PATCH] mm: memcontrol: do not recurse in direct reclaim Johannes Weiner
2016-10-25 9:07 ` Michal Hocko
2016-10-25 14:10 ` Johannes Weiner
2016-10-25 14:45 ` Michal Hocko
2016-10-25 15:01 ` Johannes Weiner
2016-10-25 15:07 ` Michal Hocko [this message]
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