2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: KOSAKI Motohiro commit 6841c8e26357904ef462650273f5d5015f7bb370 upstream. Currently, lru_add_drain_all() has two version. (1) use schedule_on_each_cpu() (2) don't use schedule_on_each_cpu() Gerald Schaefer reported it doesn't work well on SMP (not NUMA) S390 machine. offline_pages() calls lru_add_drain_all() followed by drain_all_pages(). While drain_all_pages() works on each cpu, lru_add_drain_all() only runs on the current cpu for architectures w/o CONFIG_NUMA. This let us run into the BUG_ON(!PageBuddy(page)) in __offline_isolated_pages() during memory hotplug stress test on s390. The page in question was still on the pcp list, because of a race with lru_add_drain_all() and drain_all_pages() on different cpus. Actually, Almost machine has CONFIG_UNEVICTABLE_LRU=y. Then almost machine use (1) version lru_add_drain_all although the machine is UP. Then this ifdef is not valueable. simple removing is better. Signed-off-by: KOSAKI Motohiro Cc: Christoph Lameter Cc: Lee Schermerhorn Acked-by: Gerald Schaefer Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Nick Piggin Signed-off-by: Greg Kroah-Hartman --- mm/swap.c | 13 ------------- 1 file changed, 13 deletions(-) --- a/mm/swap.c +++ b/mm/swap.c @@ -244,7 +244,6 @@ void lru_add_drain(void) put_cpu(); } -#ifdef CONFIG_NUMA static void lru_add_drain_per_cpu(struct work_struct *dummy) { lru_add_drain(); @@ -258,18 +257,6 @@ int lru_add_drain_all(void) return schedule_on_each_cpu(lru_add_drain_per_cpu); } -#else - -/* - * Returns 0 for success - */ -int lru_add_drain_all(void) -{ - lru_add_drain(); - return 0; -} -#endif - /* * Batched page_cache_release(). Decrement the reference count on all the * passed pages. If it fell to zero then remove the page from the LRU and -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/