[PATCH] cpuset: might_sleep_if check in cpuset_zones_allowed

It's too easy to incorrectly call cpuset_zone_allowed() in an atomic
context without __GFP_HARDWALL set, and when done, it is not noticed until
a tight memory situation forces allocations to be tried outside the current
cpuset.

Add a 'might_sleep_if()' check, to catch this earlier on, instead of
waiting for a similar check in the mutex_lock() code, which is only rarely
invoked.

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/cpuset.c

@@ -2261,6 +2261,7 @@ int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 	if (in_interrupt())
 		return 1;
 	node = z->zone_pgdat->node_id;
+	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
 	if (node_isset(node, current->mems_allowed))
 		return 1;
 	if (gfp_mask & __GFP_HARDWALL)	/* If hardwall request, stop here */