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Commit 75c1c91c authored by Dimitri Sivanich's avatar Dimitri Sivanich Committed by Tony Luck
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[IA64] eliminate race condition in smp_flush_tlb_mm 



A race condition exists within smp_call_function_many() when called from
smp_flush_tlb_mm().  On rare occasions the cpu_vm_mask can be cleared
while smp_call_function_many is executing, occasionally resulting in a
hung process.

Make a copy of the mask prior to calling smp_call_function_many().

Signed-off-by: default avatarDimitri Sivanich <sivanich@sgi.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 90a8a73c

arch/ia64/kernel/smp.c

+10 −3
Original line number Diff line number Diff line
@@ -293,6 +293,7 @@ smp_flush_tlb_all (void) 
void

smp_flush_tlb_mm (struct mm_struct *mm)

{

	cpumask_var_t cpus;

	preempt_disable();

	/* this happens for the common case of a single-threaded fork():  */

	if (likely(mm == current->active_mm && atomic_read(&mm->mm_users) == 1))
@@ -301,9 +302,15 @@ smp_flush_tlb_mm (struct mm_struct *mm) 
		preempt_enable();

		return;

	}



	smp_call_function_many(mm_cpumask(mm),

	if (!alloc_cpumask_var(&cpus, GFP_ATOMIC)) {

		smp_call_function((void (*)(void *))local_finish_flush_tlb_mm,

			mm, 1);

	} else {

		cpumask_copy(cpus, mm_cpumask(mm));

		smp_call_function_many(cpus,

			(void (*)(void *))local_finish_flush_tlb_mm, mm, 1);

		free_cpumask_var(cpus);

	}

	local_irq_disable();

	local_finish_flush_tlb_mm(mm);

	local_irq_enable();