From dab48dab37d2770824420d1e01730a107fade1aa Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Tue, 16 Jun 2009 15:32:37 -0700 Subject: [PATCH] page-allocator: warn if __GFP_NOFAIL is used for a large allocation __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 Acked-by: Mel Gorman Acked-by: Peter Zijlstra Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 076463cb21ba..61290ea721c8 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -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));