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| author | Peter Zijlstra <peterz@infradead.org> | 2012-06-22 13:36:05 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-08-10 00:11:14 +0100 |
| commit | b75bfc42974aaf089ae7eae5d3c6bf362f57ee93 (patch) | |
| tree | fdccebf8528123755b151ae4d504a6bb3c286368 /include/linux/init_task.h | |
| parent | 46159f6e9d9a41a0ec1914f983e7ca6e416330c1 (diff) | |
| download | lwn-b75bfc42974aaf089ae7eae5d3c6bf362f57ee93.tar.gz lwn-b75bfc42974aaf089ae7eae5d3c6bf362f57ee93.zip | |
sched: Fix race in task_group()
commit 8323f26ce3425460769605a6aece7a174edaa7d1 upstream
Stefan reported a crash on a kernel before a3e5d1091c1 ("sched:
Don't call task_group() too many times in set_task_rq()"), he
found the reason to be that the multiple task_group()
invocations in set_task_rq() returned different values.
Looking at all that I found a lack of serialization and plain
wrong comments.
The below tries to fix it using an extra pointer which is
updated under the appropriate scheduler locks. Its not pretty,
but I can't really see another way given how all the cgroup
stuff works.
Reported-and-tested-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1340364965.18025.71.camel@twins
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(backported to previous file names and layout)
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'include/linux/init_task.h')
| -rw-r--r-- | include/linux/init_task.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h index df53fdf5a304..cdde2b379c8d 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -124,8 +124,17 @@ extern struct group_info init_groups; extern struct cred init_cred; +extern struct task_group root_task_group; + +#ifdef CONFIG_CGROUP_SCHED +# define INIT_CGROUP_SCHED(tsk) \ + .sched_task_group = &root_task_group, +#else +# define INIT_CGROUP_SCHED(tsk) +#endif + #ifdef CONFIG_PERF_EVENTS -# define INIT_PERF_EVENTS(tsk) \ +# define INIT_PERF_EVENTS(tsk) \ .perf_event_mutex = \ __MUTEX_INITIALIZER(tsk.perf_event_mutex), \ .perf_event_list = LIST_HEAD_INIT(tsk.perf_event_list), @@ -162,6 +171,7 @@ extern struct cred init_cred; }, \ .tasks = LIST_HEAD_INIT(tsk.tasks), \ INIT_PUSHABLE_TASKS(tsk) \ + INIT_CGROUP_SCHED(tsk) \ .ptraced = LIST_HEAD_INIT(tsk.ptraced), \ .ptrace_entry = LIST_HEAD_INIT(tsk.ptrace_entry), \ .real_parent = &tsk, \ |