From be7bd59db71dfb6dc011c9880fec5a659430003a Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Thu, 14 Jun 2012 20:41:02 +0800 Subject: mm: fix page reclaim comment error Since there are five lists in LRU cache, the array nr in get_scan_count should be: nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan nr[2] = file inactive pages to scan; nr[3] = file active pages to scan Signed-off-by: Wanpeng Li Reviewed-by: Rik van Riel Acked-by: Minchan Kim Acked-by: KAMEZAWA Hiroyuki Acked-by: KOSAKI Motohiro Signed-off-by: Jiri Kosina --- mm/vmscan.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm/vmscan.c') diff --git a/mm/vmscan.c b/mm/vmscan.c index 33dc256033b..091ab8f8833 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1894,7 +1894,8 @@ static int vmscan_swappiness(struct mem_cgroup_zone *mz, * by looking at the fraction of the pages scanned we did rotate back * onto the active list instead of evict. * - * nr[0] = anon pages to scan; nr[1] = file pages to scan + * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan + * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan */ static void get_scan_count(struct mem_cgroup_zone *mz, struct scan_control *sc, unsigned long *nr, int priority) -- cgit v1.2.3-70-g09d2 From ab8704b8c6ec6bc8560c72969d02d2682b4a2291 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Sun, 17 Jun 2012 09:27:18 +0800 Subject: mm/vmscan: cleanup comment error in balance_pgdat Signed-off-by: Wanpeng Li Signed-off-by: Jiri Kosina --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/vmscan.c') diff --git a/mm/vmscan.c b/mm/vmscan.c index 091ab8f8833..3d1365c1786 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2864,7 +2864,7 @@ loop_again: * consider it to be no longer congested. It's * possible there are dirty pages backed by * congested BDIs but as pressure is relieved, - * spectulatively avoid congestion waits + * speculatively avoid congestion waits */ zone_clear_flag(zone, ZONE_CONGESTED); if (i <= *classzone_idx) -- cgit v1.2.3-70-g09d2 From 1c7e7f6c0703d03af6bcd5ccc11fc15d23e5ecbe Mon Sep 17 00:00:00 2001 From: Aaditya Kumar Date: Tue, 17 Jul 2012 15:48:07 -0700 Subject: mm: fix lost kswapd wakeup in kswapd_stop() Offlining memory may block forever, waiting for kswapd() to wake up because kswapd() does not check the event kthread->should_stop before sleeping. The proper pattern, from Documentation/memory-barriers.txt, is: --- waker --- event_indicated = 1; wake_up_process(event_daemon); --- sleeper --- for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (event_indicated) break; schedule(); } set_current_state() may be wrapped by: prepare_to_wait(); In the kswapd() case, event_indicated is kthread->should_stop. === offlining memory (waker) === kswapd_stop() kthread_stop() kthread->should_stop = 1 wake_up_process() wait_for_completion() === kswapd_try_to_sleep (sleeper) === kswapd_try_to_sleep() prepare_to_wait() . . schedule() . . finish_wait() The schedule() needs to be protected by a test of kthread->should_stop, which is wrapped by kthread_should_stop(). Reproducer: Do heavy file I/O in background. Do a memory offline/online in a tight loop Signed-off-by: Aaditya Kumar Acked-by: KOSAKI Motohiro Reviewed-by: Minchan Kim Acked-by: Mel Gorman Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'mm/vmscan.c') diff --git a/mm/vmscan.c b/mm/vmscan.c index 661576324c7..66e431060c0 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2688,7 +2688,10 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) * them before going back to sleep. */ set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); - schedule(); + + if (!kthread_should_stop()) + schedule(); + set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); } else { if (remaining) -- cgit v1.2.3-70-g09d2