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authorPeter Zijlstra <peterz@infradead.org>2012-06-22 15:36:05 +0400
committerIngo Molnar <mingo@kernel.org>2012-07-24 15:58:20 +0400
commit8323f26ce3425460769605a6aece7a174edaa7d1 (patch)
tree44daa0dafa49cedc9301efd1417c6c2ac338c1c7 /include/linux/init_task.h
parent88b8dac0a14c511ff41486b83a8c3d688936eec0 (diff)
downloadlinux-8323f26ce3425460769605a6aece7a174edaa7d1.tar.xz
sched: Fix race in task_group()
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>
Diffstat (limited to 'include/linux/init_task.h')
-rw-r--r--include/linux/init_task.h12
1 files changed, 11 insertions, 1 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 9e65eff6af3b..b806b821e735 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -123,8 +123,17 @@ 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),
@@ -161,6 +170,7 @@ 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, \