mm, debug: test for online nid when allocating on single node
authorDavid Rientjes <rientjes@google.com>
Tue, 10 Jan 2012 23:07:38 +0000 (15:07 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 11 Jan 2012 00:30:43 +0000 (16:30 -0800)
commitf6d7e0cb3ecc248e98fa11d83253f6174bd7e085
tree0925b5b584c8ed6718a54e6e56202686fb5b9468
parentad8a1b558e6c76fb53901956d3c8f29b82a4ccfa
mm, debug: test for online nid when allocating on single node

Calling alloc_pages_exact_node() means the allocation only passes the
zonelist of a single node into the page allocator.  If that node isn't
online, it's zonelist may never have been initialized causing a strange
oops that may not immediately be clear.

I recently debugged an issue where node 0 wasn't online and an allocator
was passing 0 to alloc_pages_exact_node() and it resulted in a NULL
pointer on zonelist->_zoneref.  If CONFIG_DEBUG_VM is enabled, though, it
would be nice to catch this a bit earlier.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/gfp.h