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| author | Vlastimil Babka <vbabka@suse.cz> | 2017-01-24 23:18:18 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-02-01 07:33:04 (GMT) |
| commit | 9b1a1ae9b5281e12893a34bcbd1686b5bcd2cd82 (patch) | |
| tree | eeb0e09321d045b46c66a1ba5a684b4d2072154e /mm/mempolicy.c | |
| parent | 6676aa65464f23e32efe1857a51fe341dfb10e03 (diff) | |
| download | linux-9b1a1ae9b5281e12893a34bcbd1686b5bcd2cd82.tar.xz | |
mm/mempolicy.c: do not put mempolicy before using its nodemask
commit d51e9894d27492783fc6d1b489070b4ba66ce969 upstream.
Since commit be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to
alloc_pages_vma") alloc_pages_vma() can potentially free a mempolicy by
mpol_cond_put() before accessing the embedded nodemask by
__alloc_pages_nodemask(). The commit log says it's so "we can use a
single exit path within the function" but that's clearly wrong. We can
still do that when doing mpol_cond_put() after the allocation attempt.
Make sure the mempolicy is not freed prematurely, otherwise
__alloc_pages_nodemask() can end up using a bogus nodemask, which could
lead e.g. to premature OOM.
Fixes: be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma")
Link: http://lkml.kernel.org/r/20170118141124.8345-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 0b859af..f757047 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2023,8 +2023,8 @@ retry_cpuset: nmask = policy_nodemask(gfp, pol); zl = policy_zonelist(gfp, pol, node); - mpol_cond_put(pol); page = __alloc_pages_nodemask(gfp, order, zl, nmask); + mpol_cond_put(pol); out: if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) goto retry_cpuset; |