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

torvalds · torvalds · commit b3c3a9cf2a28 · 2012-12-01T13:08:36.000-08:00
Pull RCU fix from Ingo Molnar:
 "Fix leaking RCU extended quiescent state, which might trigger warnings
  and mess up the extended quiescent state tracking logic into thinking
  that we are in "RCU user mode" while we aren't."

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Fix unrecovered RCU user mode in syscall_trace_leave()
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
@@ -1541,6 +1541,13 @@ void syscall_trace_leave(struct pt_regs *regs)
 {
 	bool step;
 
+	/*
+	 * We may come here right after calling schedule_user()
+	 * or do_notify_resume(), in which case we can be in RCU
+	 * user mode.
+	 */
+	rcu_user_exit();
+
 	audit_syscall_exit(regs);
 
 	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
