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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > I agree with the problem but disagree with the patch because it feels like a > terrible workaround. > > Can we just use arch_spin_lock() for the cpu_asid_lock? This might require > acquiring the raw_lock within the raw_spinlock_t, but there is precedent: > > arch/powerpc/kvm/book3s_hv_rm_mmu.c:245: > arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock); > > IMO, lockdep tracking of this lock is not necessary or possible considering the > hotplug situation. > > Or is there a reason you need lockdep working for the cpu_asid_lock? I was not aware of this possibility to bypass lockdep tracing, but this seems to work and indeed looks like less of a workaround: diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c index 4204ffa2d104..4fc2c559f1b6 100644 --- a/arch/arm/mm/context.c +++ b/arch/arm/mm/context.c @@ -254,7 +254,8 @@ void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk) && atomic64_xchg(&per_cpu(active_asids, cpu), asid)) goto switch_mm_fastpath; - raw_spin_lock_irqsave(&cpu_asid_lock, flags); + local_irq_save(flags); + arch_spin_lock(&cpu_asid_lock.raw_lock); /* Check that our ASID belongs to the current generation. */ asid = atomic64_read(&mm->context.id); if ((asid ^ atomic64_read(&asid_generation)) >> ASID_BITS) { @@ -269,7 +270,8 @@ void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk) atomic64_set(&per_cpu(active_asids, cpu), asid); cpumask_set_cpu(cpu, mm_cpumask(mm)); - raw_spin_unlock_irqrestore(&cpu_asid_lock, flags); + arch_spin_unlock(&cpu_asid_lock.raw_lock); + local_irq_restore(flags); switch_mm_fastpath: cpu_switch_mm(mm->pgd, mm); @Russell, what do you think? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel