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| author | Li Zefan <lizf@cn.fujitsu.com> | 2010-04-22 17:30:40 +0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-05-04 09:25:01 -0700 |
| commit | b629317e66fb1c6066c550dded45ab85a936163c (patch) | |
| tree | f618cd5bc21001144999a48bcb57c4bef725db06 /kernel/sched_debug.c | |
| parent | fae9c791703606636c1220e47f6690660042ce7f (diff) | |
| download | linux-b629317e66fb1c6066c550dded45ab85a936163c.tar.gz | |
sched: Fix an RCU warning in print_task()
With CONFIG_PROVE_RCU=y, a warning can be triggered: $ cat /proc/sched_debug ... kernel/cgroup.c:1649 invoked rcu_dereference_check() without protection! ... Both cgroup_path() and task_group() should be called with either rcu_read_lock or cgroup_mutex held. The rcu_dereference_check() does include cgroup_lock_is_held(), so we know that this lock is not held. Therefore, in a CONFIG_PREEMPT kernel, to say nothing of a CONFIG_PREEMPT_RT kernel, the original code could have ended up copying a string out of the freelist. This patch inserts RCU read-side primitives needed to prevent this scenario. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/sched_debug.c')
| -rw-r--r-- | kernel/sched_debug.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c index 9b49db144037..19be00ba6123 100644 --- a/kernel/sched_debug.c +++ b/kernel/sched_debug.c @@ -114,7 +114,9 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p) { char path[64]; + rcu_read_lock(); cgroup_path(task_group(p)->css.cgroup, path, sizeof(path)); + rcu_read_unlock(); SEQ_printf(m, " %s", path); } #endif |