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author | Miao Xie <miaox@cn.fujitsu.com> | 2009-01-16 10:24:10 +0800 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-01-19 02:44:00 +0100 |
commit | f90d4118bacef87894621a3e8aba853fa0c89abc (patch) | |
tree | d09a52848f5d82fc3944818f62166fee23fabc66 /kernel/mutex-debug.h | |
parent | f3b8436ad9a8ad36b3c9fa1fe030c7f38e5d3d0b (diff) | |
download | op-kernel-dev-f90d4118bacef87894621a3e8aba853fa0c89abc.zip op-kernel-dev-f90d4118bacef87894621a3e8aba853fa0c89abc.tar.gz |
cpuset: fix possible deadlock in async_rebuild_sched_domains
Lockdep reported some possible circular locking info when we tested cpuset on
NUMA/fake NUMA box.
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.29-rc1-00224-ga652504 #111
-------------------------------------------------------
bash/2968 is trying to acquire lock:
(events){--..}, at: [<ffffffff8024c8cd>] flush_work+0x24/0xd8
but task is already holding lock:
(cgroup_mutex){--..}, at: [<ffffffff8026ad1e>] cgroup_lock_live_group+0x12/0x29
which lock already depends on the new lock.
......
-------------------------------------------------------
Steps to reproduce:
# mkdir /dev/cpuset
# mount -t cpuset xxx /dev/cpuset
# mkdir /dev/cpuset/0
# echo 0 > /dev/cpuset/0/cpus
# echo 0 > /dev/cpuset/0/mems
# echo 1 > /dev/cpuset/0/memory_migrate
# cat /dev/zero > /dev/null &
# echo $! > /dev/cpuset/0/tasks
This is because async_rebuild_sched_domains has the following lock sequence:
run_workqueue(async_rebuild_sched_domains)
-> do_rebuild_sched_domains -> cgroup_lock
But, attaching tasks when memory_migrate is set has following:
cgroup_lock_live_group(cgroup_tasks_write)
-> do_migrate_pages -> flush_work
This patch fixes it by using a separate workqueue thread.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/mutex-debug.h')
0 files changed, 0 insertions, 0 deletions