From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> When cgroup_cancel_attach() is called via cgroup_attach_task(), mem_cgroup_clear_mc() can be called even when any migration was done. In such case, mc.to and mc.from is NULL. But, memcg-clean-up-waiting-move-acct-v2.patch doesn't handle this correctly and pass NULL to memcg_oom_recover. fix it. BUG: unable to handle kernel paging request at 000000000000114c IP: [<ffffffff81153bb9>] memcg_oom_recover+0x9/0x30 PGD 61ce4b067 PUD 613ea0067 PMD 0 Oops: 0000 [#1] SMP <snip> Call Trace: [<ffffffff81155359>] mem_cgroup_clear_mc+0x119/0x1c0 [<ffffffff811554de>] mem_cgroup_cancel_attach+0xe/0x10 [<ffffffff810b619c>] cgroup_attach_task+0x26c/0x2c0 [<ffffffff810b6257>] cgroup_tasks_write+0x67/0x1c0 [<ffffffff81121555>] ? might_fault+0xa5/0xb0 [<ffffffff8112150c>] ? might_fault+0x5c/0xb0 [<ffffffff810b40a2>] cgroup_file_write+0x2d2/0x330 [<ffffffff81093aa2>] ? print_lock_contention_bug+0x22/0xf0 [<ffffffff81259fef>] ? security_file_permission+0x1f/0x80 [<ffffffff8115d998>] vfs_write+0xc8/0x190 [<ffffffff8115e3a1>] sys_write+0x51/0x90 [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b Code: 20 48 39 43 20 41 bc f0 ff ff ff 75 c7 45 88 ae 48 11 00 00 45 31 e4 eb bb 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 0f 1f 44 00 00 <8b> 87 4c 11 00 00 85 c0 75 05 c9 c3 0f 1f 00 48 89 f9 31 d2 be RIP [<ffffffff81153bb9>] memcg_oom_recover+0x9/0x30 Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> --- mm/memcontrol.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) Index: mmotm-2.6.35-0611/mm/memcontrol.c =================================================================== --- mmotm-2.6.35-0611.orig/mm/memcontrol.c +++ mmotm-2.6.35-0611/mm/memcontrol.c @@ -4485,8 +4485,10 @@ static void mem_cgroup_clear_mc(void) mc.to = NULL; mc.moving_task = NULL; spin_unlock(&mc.lock); - memcg_oom_recover(from); - memcg_oom_recover(to); + if (from) + memcg_oom_recover(from); + if (to) + memcg_oom_recover(to); wake_up_all(&mc.waitq); } -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>