Commit f6d7e0cb authored Jan 10, 2012 by David Rientjes Committed by Linus Torvalds Jan 10, 2012

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>

parent ad8a1b55

include/linux/gfp.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -313,7 +313,7 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
		static inline struct page *alloc_pages_exact_node(int nid, gfp_t gfp_mask,
		unsigned int order)
		{
		VM_BUG_ON(nid < 0 \|\| nid >= MAX_NUMNODES);
		VM_BUG_ON(nid < 0 \|\| nid >= MAX_NUMNODES \|\| !node_online(nid));

		return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
		}

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