linux-kernel - Re: [PATCH] mm: non-atomically mark page accessed during page cache allocation where possible -fix

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Message-ID: <20140522000755.GB23991@suse.de>
Date:	Thu, 22 May 2014 01:07:56 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Johannes Weiner <hannes@...xchg.org>,
	Vlastimil Babka <vbabka@...e.cz>, Jan Kara <jack@...e.cz>,
	Michal Hocko <mhocko@...e.cz>, Hugh Dickins <hughd@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Dave Hansen <dave.hansen@...el.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux-MM <linux-mm@...ck.org>,
	Linux-FSDevel <linux-fsdevel@...r.kernel.org>,
	Prabhakar Lad <prabhakar.csengg@...il.com>
Subject: Re: [PATCH] mm: non-atomically mark page accessed during page cache
 allocation where possible -fix

On Wed, May 21, 2014 at 03:11:42PM -0700, Andrew Morton wrote:
> On Wed, 21 May 2014 13:09:16 +0100 Mel Gorman <mgorman@...e.de> wrote:
> 
> > > From: Andrew Morton <akpm@...ux-foundation.org>
> > > Subject: mm/shmem.c: don't run init_page_accessed() against an uninitialised pointer
> > > 
> > > If shmem_getpage() returned an error then it didn't necessarily initialise
> > > *pagep.  So shmem_write_begin() shouldn't be playing with *pagep in this
> > > situation.
> > > 
> > > Fixes an oops when "mm: non-atomically mark page accessed during page
> > > cache allocation where possible" (quite reasonably) left *pagep
> > > uninitialized.
> > > 
> > > Reported-by: Prabhakar Lad <prabhakar.csengg@...il.com>
> > > Cc: Johannes Weiner <hannes@...xchg.org>
> > > Cc: Vlastimil Babka <vbabka@...e.cz>
> > > Cc: Jan Kara <jack@...e.cz>
> > > Cc: Michal Hocko <mhocko@...e.cz>
> > > Cc: Hugh Dickins <hughd@...gle.com>
> > > Cc: Peter Zijlstra <peterz@...radead.org>
> > > Cc: Dave Hansen <dave.hansen@...el.com>
> > > Cc: Mel Gorman <mgorman@...e.de>
> > > Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> > 
> > Acked-by: Mel Gorman <mgorman@...e.de>
> 
> What to do with
> http://ozlabs.org/~akpm/mmots/broken-out/mm-non-atomically-mark-page-accessed-during-page-cache-allocation-where-possible-fix.patch?
> 
> We shouldn't need it any more.  otoh it's pretty harmless.  otooh it
> will hide bugs such as this one.
> 

Drop it.

-- 
Mel Gorman
SUSE Labs
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