| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.13 17/46] stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus() | Date | Fri, 28 Mar 2014 10:32:01 -0700 |
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3.13-stable review patch. If anyone has any objections, please let me know.
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From: Peter Zijlstra <peterz@infradead.org>
commit 177c53d943368fc97644ebc0a250dc8e2d124250 upstream.
We must use smp_call_function_single(.wait=1) for the irq_cpu_stop_queue_work() to ensure the queueing is actually done under stop_cpus_lock. Without this we could have dropped the lock by the time we do the queueing and get the race we tried to fix.
Fixes: 7053ea1a34fa ("stop_machine: Fix race between stop_two_cpus() and stop_cpus()")
Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20140228123905.GK3104@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/stop_machine.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -293,7 +293,7 @@ int stop_two_cpus(unsigned int cpu1, uns */ smp_call_function_single(min(cpu1, cpu2), &irq_cpu_stop_queue_work, - &call_args, 0); + &call_args, 1); lg_local_unlock(&stop_cpus_lock); preempt_enable();
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