On 17/05/19 10:49, Wanpeng Li wrote: > From: Wanpeng Li <[email protected]> > > WARNING: CPU: 0 PID: 13554 at > kvm/arch/x86/kvm//../../../virt/kvm/kvm_main.c:4183 kvm_resume+0x3c/0x40 [kvm] > CPU: 0 PID: 13554 Comm: step_after_susp Tainted: G OE > 5.1.0-rc4+ #1 > RIP: 0010:kvm_resume+0x3c/0x40 [kvm] > Call Trace: > syscore_resume+0x63/0x2d0 > suspend_devices_and_enter+0x9d1/0xa40 > pm_suspend+0x33a/0x3b0 > state_store+0x82/0xf0 > kobj_attr_store+0x12/0x20 > sysfs_kf_write+0x4b/0x60 > kernfs_fop_write+0x120/0x1a0 > __vfs_write+0x1b/0x40 > vfs_write+0xcd/0x1d0 > ksys_write+0x5f/0xe0 > __x64_sys_write+0x1a/0x20 > do_syscall_64+0x6f/0x6c0 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Commit ca84d1a24 (KVM: x86: Add clock sync request to hardware enable) > mentioned > that "we always hold kvm_lock when hardware_enable is called. The one place > that > doesn't need to worry about it is resume, as resuming a frozen CPU, the > spinlock > won't be taken." However, commit 6706dae9 (virt/kvm: Replace spin_is_locked() > with > lockdep) introduces a bug, it asserts when the lock is not held which is > contrary > to the original goal. > > This patch fixes it by WARN_ON when the lock is held. > > Cc: Paolo Bonzini <[email protected]> > Cc: Radim Krčmář <[email protected]> > Cc: Paul E. McKenney <[email protected]> > Signed-off-by: Wanpeng Li <[email protected]> > --- > virt/kvm/kvm_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 5fb0f16..c7eab5f 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -4096,7 +4096,7 @@ static int kvm_suspend(void) > static void kvm_resume(void) > { > if (kvm_usage_count) { > - lockdep_assert_held(&kvm_count_lock); > + WARN_ON(lockdep_is_held(&kvm_count_lock)); > hardware_enable_nolock(NULL); > } > } >
Queued, thanks. Paolo
