| Message ID | f98bac4f5052bad2c26df9ad50f7019e40434512.1643265976.git.houwenlong.hwl@antgroup.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] KVM: eventfd: Fix false positive RCU usage warning | expand |
On 1/27/22 07:54, Hou Wenlong wrote: > From: Hou Wenlong <houwenlong93@linux.alibaba.com> > > Fix the following false positive warning: > ============================= > WARNING: suspicious RCU usage > 5.16.0-rc4+ #57 Not tainted > ----------------------------- > arch/x86/kvm/../../../virt/kvm/eventfd.c:484 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > 3 locks held by fc_vcpu 0/330: > #0: ffff8884835fc0b0 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x88/0x6f0 [kvm] > #1: ffffc90004c0bb68 (&kvm->srcu){....}-{0:0}, at: vcpu_enter_guest+0x600/0x1860 [kvm] > #2: ffffc90004c0c1d0 (&kvm->irq_srcu){....}-{0:0}, at: kvm_notify_acked_irq+0x36/0x180 [kvm] > > stack backtrace: > CPU: 26 PID: 330 Comm: fc_vcpu 0 Not tainted 5.16.0-rc4+ > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > Call Trace: > <TASK> > dump_stack_lvl+0x44/0x57 > kvm_notify_acked_gsi+0x6b/0x70 [kvm] > kvm_notify_acked_irq+0x8d/0x180 [kvm] > kvm_ioapic_update_eoi+0x92/0x240 [kvm] > kvm_apic_set_eoi_accelerated+0x2a/0xe0 [kvm] > handle_apic_eoi_induced+0x3d/0x60 [kvm_intel] > vmx_handle_exit+0x19c/0x6a0 [kvm_intel] > vcpu_enter_guest+0x66e/0x1860 [kvm] > kvm_arch_vcpu_ioctl_run+0x438/0x7f0 [kvm] > kvm_vcpu_ioctl+0x38a/0x6f0 [kvm] > __x64_sys_ioctl+0x89/0xc0 > do_syscall_64+0x3a/0x90 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Since kvm_unregister_irq_ack_notifier() does synchronize_srcu(&kvm->irq_srcu), > i.e. kvm->irq_ack_notifier_list is protected by kvm->irq_srcu. And > kvm->irq_srcu SRCU read lock is held in kvm_notify_acked_irq(), it's > a false positive warning. Use hlist_for_each_entry_srcu() instead of > hlist_for_each_entry_rcu() as it also checkes if the right lock is held. > > Reviewed-by: Sean Christopherson <seanjc@google.com> > Signed-off-by: Hou Wenlong <houwenlong93@linux.alibaba.com> > --- > virt/kvm/eventfd.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c > index 2ad013b8bde9..59b1dd4a549e 100644 > --- a/virt/kvm/eventfd.c > +++ b/virt/kvm/eventfd.c > @@ -463,8 +463,8 @@ bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin) > idx = srcu_read_lock(&kvm->irq_srcu); > gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin); > if (gsi != -1) > - hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list, > - link) > + hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list, > + link, srcu_read_lock_held(&kvm->irq_srcu)) > if (kian->gsi == gsi) { > srcu_read_unlock(&kvm->irq_srcu, idx); > return true; > @@ -480,8 +480,8 @@ void kvm_notify_acked_gsi(struct kvm *kvm, int gsi) > { > struct kvm_irq_ack_notifier *kian; > > - hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list, > - link) > + hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list, > + link, srcu_read_lock_held(&kvm->irq_srcu)) > if (kian->gsi == gsi) > kian->irq_acked(kian); > } > -- > 2.31.1 > Queued, thanks. Paolo
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 2ad013b8bde9..59b1dd4a549e 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -463,8 +463,8 @@ bool kvm_irq_has_notifier(struct kvm *kvm, unsigned irqchip, unsigned pin) idx = srcu_read_lock(&kvm->irq_srcu); gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin); if (gsi != -1) - hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list, - link) + hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list, + link, srcu_read_lock_held(&kvm->irq_srcu)) if (kian->gsi == gsi) { srcu_read_unlock(&kvm->irq_srcu, idx); return true; @@ -480,8 +480,8 @@ void kvm_notify_acked_gsi(struct kvm *kvm, int gsi) { struct kvm_irq_ack_notifier *kian; - hlist_for_each_entry_rcu(kian, &kvm->irq_ack_notifier_list, - link) + hlist_for_each_entry_srcu(kian, &kvm->irq_ack_notifier_list, + link, srcu_read_lock_held(&kvm->irq_srcu)) if (kian->gsi == gsi) kian->irq_acked(kian); }