diff options
| -rw-r--r-- | arch/x86/mm/tlb.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 493559cae2d5..f086195f644c 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -310,15 +310,22 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, sync_current_stack_to_mm(next); } - /* Stop remote flushes for the previous mm */ - VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu, mm_cpumask(real_prev)) && - real_prev != &init_mm); - cpumask_clear_cpu(cpu, mm_cpumask(real_prev)); + /* + * Stop remote flushes for the previous mm. + * Skip kernel threads; we never send init_mm TLB flushing IPIs, + * but the bitmap manipulation can cause cache line contention. + */ + if (real_prev != &init_mm) { + VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu, + mm_cpumask(real_prev))); + cpumask_clear_cpu(cpu, mm_cpumask(real_prev)); + } /* * Start remote flushes and then read tlb_gen. */ - cpumask_set_cpu(cpu, mm_cpumask(next)); + if (next != &init_mm) + cpumask_set_cpu(cpu, mm_cpumask(next)); next_tlb_gen = atomic64_read(&next->context.tlb_gen); choose_new_asid(next, next_tlb_gen, &new_asid, &need_flush); |