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05 April 2024, 19:05:47 UTC
Revision 18a2f371f5edf41810f6469cb9be39931ef9deb9 authored by Mel Gorman on 05 December 2012, 22:01:41 UTC, committed by Linus Torvalds on 06 December 2012, 19:56:43 UTC 
tmpfs: fix shared mempolicy leak
 
This fixes a regression in 3.7-rc, which has since gone into stable.

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.

Reported-and-tested-by: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent c702418
History
Tip revision: 18a2f371f5edf41810f6469cb9be39931ef9deb9 authored by Mel Gorman on 05 December 2012, 22:01:41 UTC
tmpfs: fix shared mempolicy leak
Tip revision: 18a2f37
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