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

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

View File

@@ -47,6 +47,8 @@ void show_mem(unsigned int filter)
printk(KERN_INFO "Mem-info:\n");
show_free_areas(filter);
printk(KERN_INFO "Node memory in pages:\n");
if (filter & SHOW_MEM_FILTER_PAGE_COUNT)
return;
for_each_online_pgdat(pgdat) {
unsigned long present;
unsigned long flags;