]> git.karo-electronics.de Git - linux-beck.git/commit
cpu: Defer smpboot kthread unparking until CPU known to scheduler
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Sun, 12 Apr 2015 15:06:55 +0000 (08:06 -0700)
committerIngo Molnar <mingo@kernel.org>
Mon, 13 Apr 2015 06:25:16 +0000 (08:25 +0200)
commit00df35f991914db6b8bde8cf09808e19a9cffc3d
tree626f0f8fd29b55f9a203565948dfd8bb70530496
parent4bfe186dbe0a058680e4bfb0d673194f0ceaffd4
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>
include/linux/cpu.h
init/main.c
kernel/cpu.c