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page-allocator: warn if __GFP_NOFAIL is used for a large allocation

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__GFP_NOFAIL is a bad fiction.  Allocations _can_ fail, and callers should
detect and suitably handle this (and not by lamely moving the infinite
loop up to the caller level either).

Attempting to use __GFP_NOFAIL for a higher-order allocation is even
worse, so add a once-off runtime check for this to slap people around for
even thinking about trying it.

Cc: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrew Morton 2009-06-16 15:32:37 -07:00 committed by Linus Torvalds
parent 720b17e759
commit dab48dab37
1 changed files with 13 additions and 0 deletions
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13
mm/page_alloc.c
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@ -1128,6 +1128,19 @@ again:
list_del(&page->lru);
pcp->count--;
} else {
if (unlikely(gfp_flags & __GFP_NOFAIL)) {
/*
* __GFP_NOFAIL is not to be used in new code.
*
* All __GFP_NOFAIL callers should be fixed so that they
* properly detect and handle allocation failures.
*
* We most definitely don't want callers attempting to
* allocate greater than single-page units with
* __GFP_NOFAIL.
*/
WARN_ON_ONCE(order > 0);
}
spin_lock_irqsave(&zone->lock, flags);
page = __rmqueue(zone, order, migratetype);
__mod_zone_page_state(zone, NR_FREE_PAGES, -(1 << order));