On Sat, May 21, 2011 at 01:49:24AM +0900, Minchan Kim wrote: > <SNIP> > > From 8bd3f16736548375238161d1bd85f7d7c381031f Mon Sep 17 00:00:00 2001 > From: Minchan Kim <minchan.kim@xxxxxxxxx> > Date: Sat, 21 May 2011 01:37:41 +0900 > Subject: [PATCH] Prevent unending loop in __alloc_pages_slowpath > > From: Andrew Barry <abarry@xxxxxxxx> > > I believe I found a problem in __alloc_pages_slowpath, which allows a process to > get stuck endlessly looping, even when lots of memory is available. > > Running an I/O and memory intensive stress-test I see a 0-order page allocation > with __GFP_IO and __GFP_WAIT, running on a system with very little free memory. > Right about the same time that the stress-test gets killed by the OOM-killer, > the utility trying to allocate memory gets stuck in __alloc_pages_slowpath even > though most of the systems memory was freed by the oom-kill of the stress-test. > > The utility ends up looping from the rebalance label down through the > wait_iff_congested continiously. Because order=0, __alloc_pages_direct_compact > skips the call to get_page_from_freelist. Because all of the reclaimable memory > on the system has already been reclaimed, __alloc_pages_direct_reclaim skips the > call to get_page_from_freelist. Since there is no __GFP_FS flag, the block with > __alloc_pages_may_oom is skipped. The loop hits the wait_iff_congested, then > jumps back to rebalance without ever trying to get_page_from_freelist. This loop > repeats infinitely. > > The test case is pretty pathological. Running a mix of I/O stress-tests that do > a lot of fork() and consume all of the system memory, I can pretty reliably hit > this on 600 nodes, in about 12 hours. 32GB/node. > > Signed-off-by: Andrew Barry <abarry@xxxxxxxx> > Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx> > Cc: Mel Gorman <mgorman@xxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxx> -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>