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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-04-12 08:06:55 -0700
committerIngo Molnar <mingo@kernel.org>2015-04-13 08:25:16 +0200
commit00df35f991914db6b8bde8cf09808e19a9cffc3d (patch)
tree626f0f8fd29b55f9a203565948dfd8bb70530496 /init
parent4bfe186dbe0a058680e4bfb0d673194f0ceaffd4 (diff)
downloadlinux-sh-00df35f991914db6b8bde8cf09808e19a9cffc3d.tar.gz
cpu: Defer smpboot kthread unparking until CPU known to scheduler
Currently, smpboot_unpark_threads() is invoked before the incoming CPU has been added to the scheduler's runqueue structures. This might potentially cause the unparked kthread to run on the wrong CPU, since the correct CPU isn't fully set up yet. That causes a sporadic, hard to debug boot crash triggering on some systems, reported by Borislav Petkov, and bisected down to: 2a442c9c6453 ("x86: Use common outgoing-CPU-notification code") This patch places smpboot_unpark_threads() in a CPU hotplug notifier with priority set so that these kthreads are unparked just after the CPU has been added to the runqueues. Reported-and-tested-by: Borislav Petkov <bp@suse.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'init')
-rw-r--r--init/main.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/init/main.c b/init/main.c
index 6f0f1c5ff8cc..a12548c93318 100644
--- a/init/main.c
+++ b/init/main.c
@@ -384,6 +384,7 @@ static noinline void __init_refok rest_init(void)
int pid;
rcu_scheduler_starting();
+ smpboot_thread_init();
/*
* We need to spawn init first so that it obtains pid 1, however
* the init task will end up wanting to create kthreads, which, if