From: Guenter Roeck <linux@roeck-us.net>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>, Linux MM <linux-mm@kvack.org>,
Matthew Wilcox <mawilcox@microsoft.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jan Kara <jack@suse.cz>,
jlayton@redhat.com, Mel Gorman <mgorman@techsingularity.net>,
Linux-sh list <linux-sh@vger.kernel.org>
Subject: Re: [PATCH v3 2/2] slab: __GFP_ZERO is incompatible with a constructor
Date: Sat, 4 Aug 2018 07:00:35 -0700 [thread overview]
Message-ID: <e14d7aea-233d-57ae-c1e2-1d14369dd305@roeck-us.net> (raw)
In-Reply-To: <CAMuHMdXXYH_7oVJJ5sGWFj_-WbjuMdooXTqBfV+z0CzR193T3A@mail.gmail.com>
On 08/04/2018 02:28 AM, Geert Uytterhoeven wrote:
> On Sat, Aug 4, 2018 at 12:34 AM Matthew Wilcox <willy@infradead.org> wrote:
>> On Fri, Aug 03, 2018 at 02:22:57PM -0700, Guenter Roeck wrote:
>>> On Thu, Apr 12, 2018 at 12:13:22PM -0700, Matthew Wilcox wrote:
>>>> From: Matthew Wilcox <mawilcox@microsoft.com>
>>>> __GFP_ZERO requests that the object be initialised to all-zeroes,
>>>> while the purpose of a constructor is to initialise an object to a
>>>> particular pattern. We cannot do both. Add a warning to catch any
>>>> users who mistakenly pass a __GFP_ZERO flag when allocating a slab with
>>>> a constructor.
>>>>
>>>> Fixes: d07dbea46405 ("Slab allocators: support __GFP_ZERO in all allocators")
>>>> Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
>>>> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
>>>> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>>>> Acked-by: Michal Hocko <mhocko@suse.com>
>>>
>>> Seen with v4.18-rc7-139-gef46808 and v4.18-rc7-178-g0b5b1f9a78b5 when
>>> booting sh4 images in qemu:
>>
>> Thanks! It's under discussion here:
>>
>> https://marc.info/?t=153301426900002&r=1&w=2
>
> and https://www.spinics.net/lists/linux-sh/msg53298.html
>
>> also reported here with a bogus backtrace:
>>
>> https://marc.info/?l=linux-sh&m=153305755505935&w=2
>>
>> Short version: It's a bug that's been present since 2009 and nobody
>> noticed until now. And nobody's quite sure what the effect of this
>> bug is.
Though now it is making a lot of noise :-).
I just found two more 0-day bugs, so maybe improved testing and log messages
such as the one encountered here do help a bit.
Guenter
next prev parent reply other threads:[~2018-08-04 14:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 6:03 [PATCH v2 0/2] Fix __GFP_ZERO vs constructor Matthew Wilcox
2018-04-11 6:03 ` [PATCH v2 1/2] Fix NULL pointer in page_cache_tree_insert Matthew Wilcox
2018-04-11 6:03 ` [PATCH v2 2/2] slab: __GFP_ZERO is incompatible with a constructor Matthew Wilcox
2018-04-11 6:35 ` Michal Hocko
2018-04-11 13:44 ` Christopher Lameter
2018-04-11 19:24 ` Matthew Wilcox
2018-04-11 21:11 ` Christopher Lameter
2018-04-11 23:56 ` Matthew Wilcox
2018-04-12 14:10 ` Christopher Lameter
2018-04-12 14:27 ` Matthew Wilcox
2018-04-12 15:15 ` Christopher Lameter
2018-04-12 19:13 ` [PATCH v3 " Matthew Wilcox
2018-04-16 15:10 ` Christopher Lameter
2018-08-03 21:22 ` Guenter Roeck
2018-08-03 22:33 ` Matthew Wilcox
2018-08-04 9:28 ` Geert Uytterhoeven
2018-08-04 14:00 ` Guenter Roeck [this message]
2018-04-12 0:54 ` [PATCH v2 0/2] Fix __GFP_ZERO vs constructor Minchan Kim
2018-04-12 19:24 ` Matthew Wilcox
2018-04-13 12:44 ` Michal Hocko
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