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authorMel Gorman <mel@csn.ul.ie>2009-06-16 18:32:18 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-16 22:47:36 -0400
commit72807a74c0172376bba6b5b27702c9f702b526e9 (patch)
treed0f4a4a835754286ec9e2b940e950b2b68a4f61b /mm/page_alloc.c
parent092cead6175bb1b3d3078a34ba71c939d526c70b (diff)
page allocator: sanity check order in the page allocator slow path
Callers may speculatively call different allocators in order of preference trying to allocate a buffer of a given size. The order needed to allocate this may be larger than what the page allocator can normally handle. While the allocator mostly does the right thing, it should not direct reclaim or wakeup kswapd with a bogus order. This patch sanity checks the order in the slow path and returns NULL if it is too large. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5dac5d8cb148..85759cdd6973 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1446,9 +1446,6 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
1446 int zlc_active = 0; /* set if using zonelist_cache */ 1446 int zlc_active = 0; /* set if using zonelist_cache */
1447 int did_zlc_setup = 0; /* just call zlc_setup() one time */ 1447 int did_zlc_setup = 0; /* just call zlc_setup() one time */
1448 1448
1449 if (WARN_ON_ONCE(order >= MAX_ORDER))
1450 return NULL;
1451
1452 classzone_idx = zone_idx(preferred_zone); 1449 classzone_idx = zone_idx(preferred_zone);
1453zonelist_scan: 1450zonelist_scan:
1454 /* 1451 /*
@@ -1707,6 +1704,15 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
1707 struct task_struct *p = current; 1704 struct task_struct *p = current;
1708 1705
1709 /* 1706 /*
1707 * In the slowpath, we sanity check order to avoid ever trying to
1708 * reclaim >= MAX_ORDER areas which will never succeed. Callers may
1709 * be using allocators in order of preference for an area that is
1710 * too large.
1711 */
1712 if (WARN_ON_ONCE(order >= MAX_ORDER))
1713 return NULL;
1714
1715 /*
1710 * GFP_THISNODE (meaning __GFP_THISNODE, __GFP_NORETRY and 1716 * GFP_THISNODE (meaning __GFP_THISNODE, __GFP_NORETRY and
1711 * __GFP_NOWARN set) should not cause reclaim since the subsystem 1717 * __GFP_NOWARN set) should not cause reclaim since the subsystem
1712 * (f.e. slab) using GFP_THISNODE may choose to trigger reclaim 1718 * (f.e. slab) using GFP_THISNODE may choose to trigger reclaim