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authorVlastimil Babka <vbabka@suse.cz>2016-05-05 16:22:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-05 17:38:53 -0700
commit172400c69cb0d0d684b7cd75ac75872b3d7c61a1 (patch)
tree37f3ca3d190043e0f8f2487f5a88f9d527e01ec5 /mm
parentacbef7b7662953cec96c243db4009ac561d88989 (diff)
mm: fix kcompactd hang during memory offlining
Assume memory47 is the last online block left in node1. This will hang: # echo offline > /sys/devices/system/node/node1/memory47/state After a couple of minutes, the following pops up in dmesg: INFO: task bash:957 blocked for more than 120 seconds. Not tainted 4.6.0-rc6+ #6 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. bash D ffff8800b7adbaf8 0 957 951 0x00000000 Call Trace: schedule+0x35/0x80 schedule_timeout+0x1ac/0x270 wait_for_completion+0xe1/0x120 kthread_stop+0x4f/0x110 kcompactd_stop+0x26/0x40 __offline_pages.constprop.28+0x7e6/0x840 offline_pages+0x11/0x20 memory_block_action+0x73/0x1d0 memory_subsys_offline+0x47/0x60 device_offline+0x86/0xb0 store_mem_state+0xda/0xf0 dev_attr_store+0x18/0x30 sysfs_kf_write+0x37/0x40 kernfs_fop_write+0x11d/0x170 __vfs_write+0x37/0x120 vfs_write+0xa9/0x1a0 SyS_write+0x55/0xc0 entry_SYSCALL_64_fastpath+0x1a/0xa4 kcompactd is waiting for kcompactd_max_order > 0 when it's woken up to actually exit. Check kthread_should_stop() to break out of the wait. Fixes: 698b1b306 ("mm, compaction: introduce kcompactd"). Reported-by: Reza Arbab <arbab@linux.vnet.ibm.com> Tested-by: Reza Arbab <arbab@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/compaction.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 4a0d4b8ccde8..8fa254043801 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1733,7 +1733,7 @@ void compaction_unregister_node(struct node *node)
static inline bool kcompactd_work_requested(pg_data_t *pgdat)
{
- return pgdat->kcompactd_max_order > 0;
+ return pgdat->kcompactd_max_order > 0 || kthread_should_stop();
}
static bool kcompactd_node_suitable(pg_data_t *pgdat)
@@ -1797,6 +1797,8 @@ static void kcompactd_do_work(pg_data_t *pgdat)
INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages);
+ if (kthread_should_stop())
+ return;
status = compact_zone(zone, &cc);
if (zone_watermark_ok(zone, cc.order, low_wmark_pages(zone),