diff options
| -rw-r--r-- | arch/powerpc/mm/book3s64/radix_tlb.c | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c index fb66d154b26c..40f496a45cd8 100644 --- a/arch/powerpc/mm/book3s64/radix_tlb.c +++ b/arch/powerpc/mm/book3s64/radix_tlb.c @@ -653,13 +653,14 @@ static void do_exit_flush_lazy_tlb(void *arg) { struct mm_struct *mm = arg; unsigned long pid = mm->context.id; + int cpu = smp_processor_id(); /* * A kthread could have done a mmget_not_zero() after the flushing CPU - * checked mm_is_singlethreaded, and be in the process of - * kthread_use_mm when interrupted here. In that case, current->mm will - * be set to mm, because kthread_use_mm() setting ->mm and switching to - * the mm is done with interrupts off. + * checked mm_cpumask, and be in the process of kthread_use_mm when + * interrupted here. In that case, current->mm will be set to mm, + * because kthread_use_mm() setting ->mm and switching to the mm is + * done with interrupts off. */ if (current->mm == mm) goto out_flush; @@ -673,8 +674,22 @@ static void do_exit_flush_lazy_tlb(void *arg) mmdrop(mm); } - atomic_dec(&mm->context.active_cpus); - cpumask_clear_cpu(smp_processor_id(), mm_cpumask(mm)); + /* + * This IPI is only initiated from a CPU which is running mm which + * is a single-threaded process, so there will not be another racing + * IPI coming in where we would find our cpumask already clear. + * + * Nothing else clears our bit in the cpumask except CPU offlining, + * in which case we should not be taking IPIs here. However check + * this just in case the logic is wrong somewhere, and don't underflow + * the active_cpus count. + */ + if (cpumask_test_cpu(cpu, mm_cpumask(mm))) { + atomic_dec(&mm->context.active_cpus); + cpumask_clear_cpu(cpu, mm_cpumask(mm)); + } else { + WARN_ON_ONCE(1); + } out_flush: _tlbiel_pid(pid, RIC_FLUSH_ALL); |