Commit 3eaa73bd authored May 31, 2012 by Anton Vorontsov Committed by Linus Torvalds May 31, 2012

arm: use clear_tasks_mm_cpumask()



Checking for process->mm is not enough because process' main thread may
exit or detach its mm via use_mm(), but other threads may still have a
valid mm.

To fix this we would need to use find_lock_task_mm(), which would walk up
all threads and returns an appropriate task (with task lock held).

clear_tasks_mm_cpumask() has this issue fixed, so let's use it.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent cb79295e

arch/arm/kernel/smp.c

+1 −7

Original line number	Diff line number	Diff line
		@@ -109,7 +109,6 @@ static void percpu_timer_stop(void);
		int __cpu_disable(void)
		{
		unsigned int cpu = smp_processor_id();
		struct task_struct *p;
		int ret;

		ret = platform_cpu_disable(cpu);
		@@ -139,12 +138,7 @@ int __cpu_disable(void)
		flush_cache_all();
		local_flush_tlb_all();

		read_lock(&tasklist_lock);
		for_each_process(p) {
		if (p->mm)
		cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
		}
		read_unlock(&tasklist_lock);
		clear_tasks_mm_cpumask(cpu);

		return 0;
		}