[PATCH] mm: do not print backtraces on GFP_ATOMIC failures

[Rik van Riel]

Atomic allocations cannot fall back to the page eviction code
and are expected to fail.  In fact, in some network intensive
workloads, it is common to experience hundreds of GFP_ATOMIC
allocation failures.

Printing out a backtrace for every one of those expected
allocation failures accomplishes nothing good. At multi-gigabit
network speeds with jumbo frames, a burst of allocation failure
backtraces could even slow down the system.

We're better off not printing out backtraces on GFP_ATOMIC
allocation failures.

Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 975609c..5a0bddb 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -72,7 +72,7 @@ struct vm_area_struct;
 /* This equals 0, but use constants in case they ever change */
 #define GFP_NOWAIT	(GFP_ATOMIC & ~__GFP_HIGH)
 /* GFP_ATOMIC means both !wait (__GFP_WAIT not set) and use emergency pool */
-#define GFP_ATOMIC	(__GFP_HIGH)
+#define GFP_ATOMIC	(__GFP_HIGH | __GFP_NOWARN)
 #define GFP_NOIO	(__GFP_WAIT)
 #define GFP_NOFS	(__GFP_WAIT | __GFP_IO)
 #define GFP_KERNEL	(__GFP_WAIT | __GFP_IO | __GFP_FS)
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