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>,
Dan Streetman <ddstreet@ieee.org>,
Oleksiy.Avramchenko@sony.com
Subject: Re: [PATCH] z3fold: fix stale list handling
Date: Fri, 15 Sep 2017 10:34:53 +0200 [thread overview]
Message-ID: <CAMJBoFPrf_O4SeE9ve0zo1qaZdocwq=u+mYVAFQTm2NNbx9xqg@mail.gmail.com> (raw)
In-Reply-To: <20170914141532.9339436e0fb0fd85b99b8dbf@linux-foundation.org>
Hi Andrew,
2017-09-14 23:15 GMT+02:00 Andrew Morton <akpm@linux-foundation.org>:
> On Thu, 14 Sep 2017 15:59:36 +0200 Vitaly Wool <vitalywool@gmail.com> wrote:
>
>> Fix the situation when clear_bit() is called for page->private before
>> the page pointer is actually assigned. While at it, remove work_busy()
>> check because it is costly and does not give 100% guarantee anyway.
>
> Does this fix https://bugzilla.kernel.org/show_bug.cgi?id=196877 ? If
> so, the bugzilla references and a reported-by should be added.
I wish it did but it doesn't. The bug you are referring to happens
with the "unbuddied" list, and the current version of
z3fold_reclaim_page() just doesn't have that code.
This patch fixes the processing of "stale" lists, with stale lists
having been introduced with the per-CPU unbuddied lists patch, which
is pretty recent.
To fix https://bugzilla.kernel.org/show_bug.cgi?id=196877, we'll have
to either backport per-CPU unbuddied lists plus the two fixes, or
propose a separate fix.
> What are the end-user visible effects of the bug? Please always
> include this info when fixing bugs.
If page is NULL, clear_bit for page->private will result in a kernel crash.
> Should this fix be backported into -stable kernels?
No, this patch fixes the code that is not in any released kernel yet.
~vitaly
prev parent reply other threads:[~2017-09-15 8:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-14 13:59 [PATCH] z3fold: fix stale list handling Vitaly Wool
2017-09-14 21:15 ` Andrew Morton
2017-09-15 8:34 ` Vitaly Wool [this message]
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