From: Matthew Wilcox <willy@infradead.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Christopher Lameter <cl@linux.com>,
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@vger.kernel.org, Jan Kara <jack@suse.cz>,
Jeff Layton <jlayton@redhat.com>,
Mel Gorman <mgorman@techsingularity.net>,
linux-sh@vger.kernel.org
Subject: Re: [PATCH v3 2/2] slab: __GFP_ZERO is incompatible with a constructor
Date: Fri, 3 Aug 2018 15:33:57 -0700 [thread overview]
Message-ID: <20180803223357.GA23284@bombadil.infradead.org> (raw)
In-Reply-To: <20180803212257.GA5922@roeck-us.net>
On Fri, Aug 03, 2018 at 02:22:57PM -0700, Guenter Roeck wrote:
> Hi,
>
> 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
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.
next prev parent reply other threads:[~2018-08-03 22:34 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 [this message]
2018-08-04 9:28 ` Geert Uytterhoeven
2018-08-04 14:00 ` Guenter Roeck
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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