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authorChristoph Lameter <clameter@sgi.com>2006-12-06 20:33:26 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-07 08:39:25 -0800
commit952f3b51beb592f3f1de15adcdef802fc086ea91 (patch)
tree45d9b240230494d3d985400f81f963b67db1e788
parent5bcd234d881d83ac0259c6d42d98f134e31c60a8 (diff)
[PATCH] GFP_THISNODE must not trigger global reclaim
The intent of GFP_THISNODE is to make sure that an allocation occurs on a particular node. If this is not possible then NULL needs to be returned so that the caller can choose what to do next on its own (the slab allocator depends on that). However, GFP_THISNODE currently triggers reclaim before returning a failure (GFP_THISNODE means GFP_NORETRY is set). If we have over allocated a node then we will currently do some reclaim before returning NULL. The caller may want memory from other nodes before reclaim should be triggered. (If the caller wants reclaim then he can directly use __GFP_THISNODE instead). There is no flag to avoid reclaim in the page allocator and adding yet another GFP_xx flag would be difficult given that we are out of available flags. So just compare and see if all bits for GFP_THISNODE (__GFP_THISNODE, __GFP_NORETRY and __GFP_NOWARN) are set. If so then we return NULL before waking up kswapd. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--mm/page_alloc.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5d123b39971..dc8753bdd47 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1151,6 +1151,17 @@ restart:
if (page)
goto got_pg;
+ /*
+ * GFP_THISNODE (meaning __GFP_THISNODE, __GFP_NORETRY and
+ * __GFP_NOWARN set) should not cause reclaim since the subsystem
+ * (f.e. slab) using GFP_THISNODE may choose to trigger reclaim
+ * using a larger set of nodes after it has established that the
+ * allowed per node queues are empty and that nodes are
+ * over allocated.
+ */
+ if (NUMA_BUILD && (gfp_mask & GFP_THISNODE) == GFP_THISNODE)
+ goto nopage;
+
for (z = zonelist->zones; *z; z++)
wakeup_kswapd(*z, order);