[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: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/smp.c b/arch/ia64/kernel/smp.c
index dabeefe2..be450a3 100644
--- a/arch/ia64/kernel/smp.c
+++ b/arch/ia64/kernel/smp.c
@@ -293,6 +293,7 @@
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 @@
preempt_enable();
return;
}
-
- smp_call_function_many(mm_cpumask(mm),
- (void (*)(void *))local_finish_flush_tlb_mm, mm, 1);
+ 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();