Messages in this thread | | | Date | Wed, 5 Dec 2012 09:52:21 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH] tmpfs: fix shared mempolicy leak |
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On Tue, Dec 04, 2012 at 11:24:30PM -0800, Hugh Dickins wrote: > From: Mel Gorman <mgorman@suse.de> > > Commit 00442ad04a5e ("mempolicy: fix a memory corruption by refcount > imbalance in alloc_pages_vma()") changed get_vma_policy() to raise the > refcount on a shmem shared mempolicy; whereas shmem_alloc_page() went > on expecting alloc_page_vma() to drop the refcount it had acquired. > This deserves a rework: but for now fix the leak in shmem_alloc_page(). > > Hugh: shmem_swapin() did not need a fix, but surely it's clearer to use > the same refcounting there as in shmem_alloc_page(), delete its onstack > mempolicy, and the strange mpol_cond_copy() and __mpol_cond_copy() - > those were invented to let swapin_readahead() make an unknown number of > calls to alloc_pages_vma() with one mempolicy; but since 00442ad04a5e, > alloc_pages_vma() has kept refcount in balance, so now no problem. >
Agreed. Anything that reduces the complexity of the mempolicy ref counting is worthwhile even if it's only by a small bit.
> Reported-by: Tommi Rantala <tt.rantala@gmail.com> > Awaiting-signed-off-by: Mel Gorman <mgorman@suse.de> > Signed-off-by: Hugh Dickins <hughd@google.com> > Cc: stable@vger.kernel.org
Thanks Hugh for turning gibber into a patch!
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tommi, just in case, can you confirm this fixes the problem for you please?
-- Mel Gorman SUSE Labs
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