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Subject[PATCH 1/5] metag: use clear_tasks_mm_cpumask()
Date
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() was introduced in v3.5-rc1 to fix this issue,
so let's use it for metag too.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/metag/kernel/smp.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/metag/kernel/smp.c b/arch/metag/kernel/smp.c
index 86fdda4..b813515 100644
--- a/arch/metag/kernel/smp.c
+++ b/arch/metag/kernel/smp.c
@@ -276,7 +276,6 @@ static DECLARE_COMPLETION(cpu_killed);
int __cpuexit __cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
- struct task_struct *p;

/*
* Take this CPU offline. Once we clear this, we can't return,
@@ -296,12 +295,7 @@ int __cpuexit __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;
}
--
1.8.1.2



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