From: Vitaly Wool <vitalywool@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Oleksiy.Avramchenko@sony.com
Subject: Re: [PATCH] z3fold: limit use of stale list for allocation
Date: Sun, 4 Mar 2018 12:18:47 -0800 [thread overview]
Message-ID: <CAMJBoFNLF6__MnHEqOqPQpRucsp3hrSba6qSSjorEVttGx=LyA@mail.gmail.com> (raw)
In-Reply-To: <20180216162809.30b2278f0cacefa66c95c1aa@linux-foundation.org>
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[sorry for answering only now, this email slipped through somehow]
2018-02-16 16:28 GMT-08:00 Andrew Morton <akpm@linux-foundation.org>:
> On Sat, 10 Feb 2018 12:02:52 +0100 Vitaly Wool <vitalywool@gmail.com>
> wrote:
>
> > Currently if z3fold couldn't find an unbuddied page it would first
> > try to pull a page off the stale list. The problem with this
> > approach is that we can't 100% guarantee that the page is not
> > processed by the workqueue thread at the same time unless we run
> > cancel_work_sync() on it, which we can't do if we're in an atomic
> > context. So let's just limit stale list usage to non-atomic
> > contexts only.
>
> This smells like a bugfix. What are the end-user visible effects of
> the bug?
>
>
I have only seen this happening in real life once, and then z3fold ended up
using a page which had been already freed and got blocked on a spinlock.
~Vitaly
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next prev parent reply other threads:[~2018-03-04 20:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-10 11:02 Vitaly Wool
2018-02-17 0:28 ` Andrew Morton
2018-03-04 20:18 ` Vitaly Wool [this message]
-- strict thread matches above, loose matches on Subject: below --
2018-02-10 8:57 Vitaly Vul
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