Messages in this thread | | | Date | Tue, 3 Jul 2012 13:19:01 -0700 | Subject | Re: [ 07/48] mm: fix slab->page _count corruption when using slub | From | Pravin Shelar <> |
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Applying just this patch does not solve whole problem. There is another patch which needs to be backported. Discussion on that is not concluded yet. so I think we can drop this patch for now. ref : http://www.vacationhomexchg.com/lists/linux-mm/msg36054.html
Thanks, Pravin.
On Mon, Jul 2, 2012 at 6:17 PM, Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com> wrote: > On Mon, Jul 02, 2012 at 08:56:32PM -0300, Herton Ronaldo Krzesinski wrote: >> So, 3.2 didn't have the CONFIG_HAVE_CMPXCHG_DOUBLE and >> CONFIG_HAVE_ALIGNED_STRUCT_PAGE defines, it had instead CMPXCHG_DOUBLE >> and HAVE_ALIGNED_STRUCT_PAGE is a new logic. So the patch is broken for >> 3.2 indeed. > > So here is a proposed backport for 3.2, I tested it etc., but please > someone review/ack it as well... > > From: Pravin B Shelar <pshelar@nicira.com> > Subject: mm: fix slab->page _count corruption when using slub > > commit abca7c4965845924f65d40e0aa1092bdd895e314 upstream. > > On arches that do not support this_cpu_cmpxchg_double() slab_lock is used > to do atomic cmpxchg() on double word which contains page->_count. The > page count can be changed from get_page() or put_page() without taking > slab_lock. That corrupts page counter. > > Fix it by moving page->_count out of cmpxchg_double data. So that slub > does no change it while updating slub meta-data in struct page. > > [akpm@linux-foundation.org: use standard comment layout, tweak comment text] > Reported-by: Amey Bhide <abhide@nicira.com> > Signed-off-by: Pravin B Shelar <pshelar@nicira.com> > Acked-by: Christoph Lameter <cl@linux.com> > Cc: Pekka Enberg <penberg@cs.helsinki.fi> > Cc: Andrea Arcangeli <aarcange@redhat.com> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Ben Hutchings <ben@decadent.org.uk> > [herton: backport to 3.2, use CONFIG_CMPXCHG_DOUBLE] > Signed-off-by: Herton R. Krzesinski <herton@canonical.com> > --- > include/linux/mm_types.h | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 5b42f1b..2153639 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -56,8 +56,17 @@ struct page { > }; > > union { > +#ifdef CONFIG_CMPXCHG_DOUBLE > /* Used for cmpxchg_double in slub */ > unsigned long counters; > +#else > + /* > + * Keep _count separate from slub cmpxchg_double data. > + * As the rest of the double word is protected by > + * slab_lock but _count is not. > + */ > + unsigned counters; > +#endif > > struct { > > -- > 1.7.9.5 > > > -- > []'s > Herton
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