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| author | Wanpeng Li <wanpengli@tencent.com> | 2022-05-19 01:49:13 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-05-20 09:10:33 -0400 |
| commit | e332b55fe79cca72451fe0b797219bd9fe6b9434 (patch) | |
| tree | fe96c073026e23a94d2d022b4f80b2bf041b5b14 /virt | |
| parent | c41ef29cc1d4fa4ac5f1bb8e6ab57bf6f02cf878 (diff) | |
| download | linux-e332b55fe79cca72451fe0b797219bd9fe6b9434.tar.bz2 | |
KVM: eventfd: Fix false positive RCU usage warning
The splat below can be seen when running kvm-unit-test:
=============================
WARNING: suspicious RCU usage
5.18.0-rc7 #5 Tainted: G IOE
-----------------------------
/home/kernel/linux/arch/x86/kvm/../../../virt/kvm/eventfd.c:80 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
4 locks held by qemu-system-x86/35124:
#0: ffff9725391d80b8 (&vcpu->mutex){+.+.}-{4:4}, at: kvm_vcpu_ioctl+0x77/0x710 [kvm]
#1: ffffbd25cfb2a0b8 (&kvm->srcu){....}-{0:0}, at: vcpu_enter_guest+0xdeb/0x1900 [kvm]
#2: ffffbd25cfb2b920 (&kvm->irq_srcu){....}-{0:0}, at: kvm_hv_notify_acked_sint+0x79/0x1e0 [kvm]
#3: ffffbd25cfb2b920 (&kvm->irq_srcu){....}-{0:0}, at: irqfd_resampler_ack+0x5/0x110 [kvm]
stack backtrace:
CPU: 2 PID: 35124 Comm: qemu-system-x86 Tainted: G IOE 5.18.0-rc7 #5
Call Trace:
<TASK>
dump_stack_lvl+0x6c/0x9b
irqfd_resampler_ack+0xfd/0x110 [kvm]
kvm_notify_acked_gsi+0x32/0x90 [kvm]
kvm_hv_notify_acked_sint+0xc5/0x1e0 [kvm]
kvm_hv_set_msr_common+0xec1/0x1160 [kvm]
kvm_set_msr_common+0x7c3/0xf60 [kvm]
vmx_set_msr+0x394/0x1240 [kvm_intel]
kvm_set_msr_ignored_check+0x86/0x200 [kvm]
kvm_emulate_wrmsr+0x4f/0x1f0 [kvm]
vmx_handle_exit+0x6fb/0x7e0 [kvm_intel]
vcpu_enter_guest+0xe5a/0x1900 [kvm]
kvm_arch_vcpu_ioctl_run+0x16e/0xac0 [kvm]
kvm_vcpu_ioctl+0x279/0x710 [kvm]
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
resampler-list is protected by irq_srcu (see kvm_irqfd_assign), so fix
the false positive by using list_for_each_entry_srcu().
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1652950153-12489-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/eventfd.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 59b1dd4a549e..2a3ed401ce46 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -77,7 +77,8 @@ irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian) idx = srcu_read_lock(&kvm->irq_srcu); - list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link) + list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link, + srcu_read_lock_held(&kvm->irq_srcu)) eventfd_signal(irqfd->resamplefd, 1); srcu_read_unlock(&kvm->irq_srcu, idx); |