On Mon, 9 Dec 2013 13:56:37 -0800 (PST) David Rientjes <rientjes@xxxxxxxxxx> wrote: > __GFP_NOFAIL specifies that the page allocator cannot fail to return > memory. Allocators that call it may not even check for NULL upon > returning. > > It turns out GFP_NOWAIT | __GFP_NOFAIL or GFP_ATOMIC | __GFP_NOFAIL can > actually return NULL. More interestingly, processes that are doing > direct reclaim and have PF_MEMALLOC set may also return NULL for any > __GFP_NOFAIL allocation. __GFP_NOFAIL is a nasty thing and making it pretend to work even better is heading in the wrong direction, surely? It would be saner to just disallow these even-sillier combinations. Can we fix up the current callers then stick a WARN_ON() in there? > This patch fixes it so that the page allocator never actually returns > NULL as expected for __GFP_NOFAIL. It turns out that no code actually > does anything as crazy as GFP_ATOMIC | __GFP_NOFAIL currently, so this > is more for correctness than a bug fix for that issue. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>