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From: Andrew Morton <akpm@linux-foundation.org>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	bugzilla-daemon@bugzilla.kernel.org, linux-mm@kvack.org,
	Luke Dashjr <luke@dashjr.org>, Ming Lei <ming.lei@canonical.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	luke-jr+linuxbugs@utopios.org, dri-devel@lists.freedesktop.org,
	Pekka Enberg <penberg@kernel.org>, Mel Gorman <mel@csn.ul.ie>,
	David Rientjes <rientjes@google.com>,
	Christoph Lameter <cl@linux.com>
Subject: Re: [Bug 87891] New: kernel BUG at mm/slab.c:2625!
Date: Tue, 11 Nov 2014 17:44:12 -0800	[thread overview]
Message-ID: <20141111174412.ba0ac86f.akpm@linux-foundation.org> (raw)
In-Reply-To: <20141112012244.GA21576@js1304-P5Q-DELUXE>

On Wed, 12 Nov 2014 10:22:45 +0900 Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:

> On Tue, Nov 11, 2014 at 05:02:43PM -0800, Andrew Morton wrote:
> > On Wed, 12 Nov 2014 00:54:01 +0000 Luke Dashjr <luke@dashjr.org> wrote:
> > 
> > > On Wednesday, November 12, 2014 12:49:13 AM Andrew Morton wrote:
> > > > But anyway - Luke, please attach your .config to
> > > > https://bugzilla.kernel.org/show_bug.cgi?id=87891?
> > > 
> > > Done: https://bugzilla.kernel.org/attachment.cgi?id=157381
> > > 
> > 
> > OK, thanks.  No CONFIG_HIGHMEM of course.  I'm stumped.
> 
> Hello, Andrew.
> 
> I think that the cause is GFP_HIGHMEM.
> GFP_HIGHMEM is always defined regardless CONFIG_HIGHMEM.
> Please look at the do_huge_pmd_anonymous_page().
> It calls alloc_hugepage_vma() and then alloc_pages_vma() is called
> with alloc_hugepage_gfpmask(). This gfpmask includes GFP_TRANSHUGE
> and then GFP_HIGHUSER_MOVABLE.

OK.

So where's the bug?  I'm inclined to say that it's in ttm.  It's taking
a gfp_mask which means "this is the allocation attempt which we are
attempting to satisfy" and uses that for its own allocation.

But ttm has no business using that gfp_mask for its own allocation
attempt.  If anything it should use something like, err,

	GFP_KERNEL & ~__GFP_IO & ~__GFP_FS | __GFP_HIGH

although as I mentioned earlier, it would be better to avoid allocation
altogether.

Poor ttm guys - this is a bit of a trap we set for them.
_______________________________________________
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dri-devel@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Luke Dashjr <luke@dashjr.org>, Christoph Lameter <cl@linux.com>,
	Ming Lei <ming.lei@canonical.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>, Mel Gorman <mel@csn.ul.ie>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Pauli Nieminen <suokkos@gmail.com>,
	Dave Airlie <airlied@linux.ie>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	bugzilla-daemon@bugzilla.kernel.org,
	luke-jr+linuxbugs@utopios.org, dri-devel@lists.freedesktop.org,
	linux-mm@kvack.org
Subject: Re: [Bug 87891] New: kernel BUG at mm/slab.c:2625!
Date: Tue, 11 Nov 2014 17:44:12 -0800	[thread overview]
Message-ID: <20141111174412.ba0ac86f.akpm@linux-foundation.org> (raw)
In-Reply-To: <20141112012244.GA21576@js1304-P5Q-DELUXE>

On Wed, 12 Nov 2014 10:22:45 +0900 Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:

> On Tue, Nov 11, 2014 at 05:02:43PM -0800, Andrew Morton wrote:
> > On Wed, 12 Nov 2014 00:54:01 +0000 Luke Dashjr <luke@dashjr.org> wrote:
> > 
> > > On Wednesday, November 12, 2014 12:49:13 AM Andrew Morton wrote:
> > > > But anyway - Luke, please attach your .config to
> > > > https://bugzilla.kernel.org/show_bug.cgi?id=87891?
> > > 
> > > Done: https://bugzilla.kernel.org/attachment.cgi?id=157381
> > > 
> > 
> > OK, thanks.  No CONFIG_HIGHMEM of course.  I'm stumped.
> 
> Hello, Andrew.
> 
> I think that the cause is GFP_HIGHMEM.
> GFP_HIGHMEM is always defined regardless CONFIG_HIGHMEM.
> Please look at the do_huge_pmd_anonymous_page().
> It calls alloc_hugepage_vma() and then alloc_pages_vma() is called
> with alloc_hugepage_gfpmask(). This gfpmask includes GFP_TRANSHUGE
> and then GFP_HIGHUSER_MOVABLE.

OK.

So where's the bug?  I'm inclined to say that it's in ttm.  It's taking
a gfp_mask which means "this is the allocation attempt which we are
attempting to satisfy" and uses that for its own allocation.

But ttm has no business using that gfp_mask for its own allocation
attempt.  If anything it should use something like, err,

	GFP_KERNEL & ~__GFP_IO & ~__GFP_FS | __GFP_HIGH

although as I mentioned earlier, it would be better to avoid allocation
altogether.

Poor ttm guys - this is a bit of a trap we set for them.

--
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  reply	other threads:[~2014-11-12  1:43 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-87891-27@https.bugzilla.kernel.org/>
2014-11-11 23:31 ` [Bug 87891] New: kernel BUG at mm/slab.c:2625! Andrew Morton
2014-11-11 23:31   ` Andrew Morton
2014-11-12  0:36   ` Christoph Lameter
2014-11-12  0:49     ` Andrew Morton
2014-11-12  0:54       ` Luke Dashjr
2014-11-12  1:02         ` Andrew Morton
2014-11-12  1:22           ` Joonsoo Kim
2014-11-12  1:44             ` Andrew Morton [this message]
2014-11-12  1:44               ` Andrew Morton
2014-11-12  2:13               ` Joonsoo Kim
2014-11-12  4:08               ` Tetsuo Handa
2014-11-12  4:38                 ` Andrew Morton
2014-11-12  4:38                   ` Andrew Morton
2014-11-13 13:43                   ` [PATCH] drm/ttm: Avoid memory allocation from shrinker functions Tetsuo Handa
2014-11-12  1:22       ` [Bug 87891] New: kernel BUG at mm/slab.c:2625! Kirill A. Shutemov
2014-11-12  1:47         ` Kirill A. Shutemov
2014-11-12  1:56           ` Andrew Morton
2014-11-12  1:56             ` Andrew Morton
2014-11-12  2:07             ` Kirill A. Shutemov
2014-11-12  2:17         ` Joonsoo Kim
2014-11-12  2:37           ` Kirill A. Shutemov
2014-11-12  8:21             ` Joonsoo Kim
2014-11-12 10:39           ` Mel Gorman
2014-11-13  6:37             ` Joonsoo Kim
2014-11-12  0:44   ` Joonsoo Kim
2014-11-12  0:53     ` Andrew Morton
2014-11-12  0:53       ` Andrew Morton
2014-11-12  1:04       ` Christoph Lameter
2014-11-13  7:04   ` Vlastimil Babka

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