On Thu, 2011-07-28 at 14:04 -0700, Hugh Dickins wrote:
> On Thu, 28 Jul 2011, a...@linux-foundation.org wrote:
> > From: Hugh Dickins <hu...@google.com>
> > 
> > My load tests on PowerPC freeze within minutes in __slab_free().  I
> > happened to try PPC first, didn't try without this fix on x86.
> > 
> > It looks as if the author was interrupted while devising the new
> > cmpxchg_double_slab() version of __slab_free(): its decision to
> > spin_lock_irqsave() depends on several uninitialized fields, and fixing
> > that (by copying page to new) mostly fixes it.
> > 
> > But I didn't think about it very much, and this may well not be what the
> > author intends; and I have seen a couple of much rarer freezes in
> > __slab_free() on PPC (not yet on x86) even after applying this.
> > 
> > Signed-off-by: Hugh Dickins <hu...@google.com>
> > Cc: Pekka Enberg <penb...@cs.helsinki.fi>
> > Cc: Christoph Lameter <c...@linux.com>
> > Cc: <sta...@kernel.org>
> > Signed-off-by: Andrew Morton <a...@linux-foundation.org>
> 
> Sorry, no, I don't think this patch should be going anywhere now.
> 
> Certainly not to sta...@kernel.org: it was a patch to linux-next
> and mmotm a couple of weeks ago, not to anything upstream.
> 
> Christoph refined his linux-next struct page unions, and added
> some irq disabling in slub slow path, to fix the problem without
> this hack of mine.
> 
> But I believe this is all in a branch of Pekka's tree which he
> intends to invite Linus to pull, but may or may not make it
> into 3.1 (it enlarges x86_64 struct page from 56 to 64 bytes).

Yup. Dunno why Andrew picked it up. This patch shouldn't be needed for
anything.

So NAK NAK NAK ;-)

                        Pekka

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