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authorLi Zefan <lizefan@huawei.com>2014-02-27 11:19:03 +0100
committerTejun Heo <tj@kernel.org>2014-02-27 15:35:59 +0100
commit4729583006772b9530404bc1bb7c3aa4a10ffd4d (patch)
tree06b53d469d09463d7c06dd9440870e84ced7b46c /net/sctp/sm_statefuns.c
parentcgroup: update cgroup_enable_task_cg_lists() to grab siglock (diff)
downloadlinux-4729583006772b9530404bc1bb7c3aa4a10ffd4d.tar.xz
linux-4729583006772b9530404bc1bb7c3aa4a10ffd4d.zip
cpuset: fix a locking issue in cpuset_migrate_mm()
I can trigger a lockdep warning: # mount -t cgroup -o cpuset xxx /cgroup # mkdir /cgroup/cpuset # mkdir /cgroup/tmp # echo 0 > /cgroup/tmp/cpuset.cpus # echo 0 > /cgroup/tmp/cpuset.mems # echo 1 > /cgroup/tmp/cpuset.memory_migrate # echo $$ > /cgroup/tmp/tasks # echo 1 > /cgruop/tmp/cpuset.mems =============================== [ INFO: suspicious RCU usage. ] 3.14.0-rc1-0.1-default+ #32 Not tainted ------------------------------- include/linux/cgroup.h:682 suspicious rcu_dereference_check() usage! ... [<ffffffff81582174>] dump_stack+0x72/0x86 [<ffffffff810b8f01>] lockdep_rcu_suspicious+0x101/0x140 [<ffffffff81105ba1>] cpuset_migrate_mm+0xb1/0xe0 ... We used to hold cgroup_mutex when calling cpuset_migrate_mm(), but now we hold cpuset_mutex, which causes task_css() to complain. This is not a false-positive but a real issue. Holding cpuset_mutex won't prevent a task from migrating to another cpuset, and it won't prevent the original task->cgroup from destroying during this change. Fixes: 5d21cc2db040 (cpuset: replace cgroup_mutex locking with cpuset internal locking) Cc: <stable@vger.kernel.org> # 3.9+ Signed-off-by: Li Zefan <lizefan@huawei.com> Sigend-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'net/sctp/sm_statefuns.c')
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