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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-04-12 18:06:55 +0300
committerIngo Molnar <mingo@kernel.org>2015-04-13 09:25:16 +0300
commit00df35f991914db6b8bde8cf09808e19a9cffc3d (patch)
tree626f0f8fd29b55f9a203565948dfd8bb70530496 /include/linux/cpu.h
parent4bfe186dbe0a058680e4bfb0d673194f0ceaffd4 (diff)
downloadlinux-00df35f991914db6b8bde8cf09808e19a9cffc3d.tar.xz
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 'include/linux/cpu.h')
-rw-r--r--include/linux/cpu.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index d028721748d4..091badf0f6ba 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -73,6 +73,7 @@ enum {
/* migration should happen before other stuff but after perf */
CPU_PRI_PERF = 20,
CPU_PRI_MIGRATION = 10,
+ CPU_PRI_SMPBOOT = 9,
/* bring up workqueues before normal notifiers and down after */
CPU_PRI_WORKQUEUE_UP = 5,
CPU_PRI_WORKQUEUE_DOWN = -5,
@@ -165,6 +166,7 @@ static inline void __unregister_cpu_notifier(struct notifier_block *nb)
}
#endif
+void smpboot_thread_init(void);
int cpu_up(unsigned int cpu);
void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);