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mm, show_mem: suppress page counts in non-blockable contexts

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On large systems with a lot of memory, walking all RAM to determine page
types may take a half second or even more.

In non-blockable contexts, the page allocator will emit a page allocation
failure warning unless __GFP_NOWARN is specified.  In such contexts, irqs
are typically disabled and such a lengthy delay may even result in NMI
watchdog timeouts.

To fix this, suppress the page walk in such contexts when printing the
page allocation failure warning.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes
2013-04-29 15:06:11 -07:00
committed by Linus Torvalds
parent fe0bfaaff8
commit 4b59e6c473
8 changed files with 24 additions and 1 deletions
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3
include/linux/mm.h
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@@ -899,7 +899,8 @@ extern void pagefault_out_of_memory(void);
* Flags passed to show_mem() and show_free_areas() to suppress output in
* various contexts.
*/
#define SHOW_MEM_FILTER_NODES (0x0001u) /* filter disallowed nodes */
#define SHOW_MEM_FILTER_NODES (0x0001u) /* disallowed nodes */
#define SHOW_MEM_FILTER_PAGE_COUNT (0x0002u) /* page type count */
extern void show_free_areas(unsigned int flags);
extern bool skip_free_areas_node(unsigned int flags, int nid);