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Subject[037/119] page allocator: Do not allow interrupts to use ALLOC_HARDER
2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Mel Gorman <mel@csn.ul.ie>

commit 9d0ed60fe9cd1fbf57f755cd27a23ae9114d7210 upstream.

Commit 341ce06f69abfafa31b9468410a13dbd60e2b237 ("page allocator:
calculate the alloc_flags for allocation only once") altered watermark
logic slightly by allowing rt_tasks that are handling an interrupt to set
ALLOC_HARDER. This patch brings the watermark logic more in line with
2.6.30.

This change results in a reduction of the number high-order GFP_ATOMIC
allocation failures reported. See
http://www.gossamer-threads.com/lists/linux/kernel/1144153

[rientjes@google.com: Spotted the problem]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.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@suse.de>

---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1715,7 +1715,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
* See also cpuset_zone_allowed() comment in kernel/cpuset.c.
*/
alloc_flags &= ~ALLOC_CPUSET;
- } else if (unlikely(rt_task(p)))
+ } else if (unlikely(rt_task(p)) && !in_interrupt())
alloc_flags |= ALLOC_HARDER;

if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) {



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