commit e09d13c4c8805546d97bcc8c508c07f7d8f4c8e8
author Linus Torvalds <torvalds@linux-foundation.org> Sat Apr 27 10:08:09 2013 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> Sat Apr 27 10:08:09 2013 -0700
tree 49304cce7cbc67dd188bd35183b89f664343ec27
parent d7d7271f421f1e45289f2a737c7f636c02c673ce
parent c79aa0d96548aee50570209eb2d45c8f4ac49230

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fix from Ingo Molnar:
 "This fix adds missing RCU read protection"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  events: Protect access via task_subsys_state_check()

kernel/events/core.c

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4d3124b..9fcb094 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4596,6 +4596,7 @@
 	struct perf_event_context *ctx;
 	int ctxn;
 
+	rcu_read_lock();
 	for_each_task_context_nr(ctxn) {
 		ctx = task->perf_event_ctxp[ctxn];
 		if (!ctx)
@@ -4603,6 +4604,7 @@
 
 		perf_event_enable_on_exec(ctx);
 	}
+	rcu_read_unlock();
 
 	if (!atomic_read(&nr_comm_events))
 		return;