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

From: Andrew Morton
Date: Wed May 21 2014 - 18:11:49 EST


On Wed, 21 May 2014 13:09:16 +0100 Mel Gorman <mgorman@xxxxxxx> wrote:

> > From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > 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@xxxxxxxxx>
> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> > Cc: Vlastimil Babka <vbabka@xxxxxxx>
> > Cc: Jan Kara <jack@xxxxxxx>
> > Cc: Michal Hocko <mhocko@xxxxxxx>
> > Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> > Cc: Mel Gorman <mgorman@xxxxxxx>
> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>
> Acked-by: Mel Gorman <mgorman@xxxxxxx>

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.

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