On 23/05/2019 16:34, Paul Mackerras wrote: > Recent reports of lockdep splats in the HV KVM code revealed that it > was taking the kvm->lock mutex in several contexts where a vcpu mutex > was already held. Lockdep has only started warning since I added code > to take the vcpu mutexes in the XIVE device release functions, but > since Documentation/virtual/kvm/locking.txt specifies that the vcpu > mutexes nest inside kvm->lock, it seems that the new code is correct > and it is most of the old uses of kvm->lock that are wrong. > > This series should fix the problems, by adding new mutexes that nest > inside the vcpu mutexes and using them instead of kvm->lock. I applied these 4, compiled, installed, rebooted, tried running a guest (which failed because I also updated QEMU and its cli has changed), got this. So VM was created and then destroyed without executing a single instruction, if that matters. systemd-journald[1278]: Successfully sent stream file descriptor to service manager. systemd-journald[1278]: Successfully sent stream file descriptor to service manager. WARNING: CPU: 3 PID: 7697 at arch/powerpc/kvm/book3s_rtas.c:285 kvmppc_rtas_tokens_free+0x100/0x108 [kvm] Modules linked in: bridge stp llc kvm_hv kvm rpcrdma ib_iser ib_srp rdma_ucm ib_umad sunrpc rdma_cm ib_ipoib iw_cm libiscsi ib_cm scsi_transport_iscsi mlx5_ib ib_uverbs ib_core vmx_crypto crct10dif_vp msum crct10dif_common at24 sg xfs libcrc32c crc32c_vpmsum mlx5_core mlxfw autofs4 CPU: 3 PID: 7697 Comm: qemu-kvm Not tainted 5.2.0-rc1-le_nv2_aikATfstn1-p1 #496 NIP: c00800000f3ab678 LR: c00800000f3ab66c CTR: c000000000198210 REGS: c000003fdf873680 TRAP: 0700 Not tainted (5.2.0-rc1-le_nv2_aikATfstn1-p1) MSR: 900000000282b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24008882 XER: 20040000 CFAR: c000000000198364 IRQMASK: 0 GPR00: c00800000f3ab66c c000003fdf873910 c00800000f3d8f00 0000000000000000 GPR04: c000003f4c984630 0000000000000000 00000000d5952dee 0000000000000000 GPR08: 0000000000000000 0000000000000000 0000000000000000 c00800000f3b95c0 GPR12: c000000000198210 c000003fffffbb80 00007ffff20d57a8 0000000000000000 GPR16: 0000000000000000 0000000000000008 0000000119dcd0c0 0000000000000001 GPR20: c000003f4c98f530 c000003f4c980098 c000003f4c984188 0000000000000000 GPR24: c000003f4c98a740 0000000000000000 c000003fdf8dd200 c00800000f3d1c18 GPR28: c000003f4c98a858 c000003f4c980000 c000003f4c9840c8 c000003f4c980000 NIP [c00800000f3ab678] kvmppc_rtas_tokens_free+0x100/0x108 [kvm] LR [c00800000f3ab66c] kvmppc_rtas_tokens_free+0xf4/0x108 [kvm] Call Trace: [c000003fdf873910] [c00800000f3ab66c] kvmppc_rtas_tokens_free+0xf4/0x108 [kvm] (unreliable) [c000003fdf873960] [c00800000f3aa640] kvmppc_core_destroy_vm+0x48/0xa8 [kvm] [c000003fdf873990] [c00800000f3a4b08] kvm_arch_destroy_vm+0x130/0x190 [kvm] [c000003fdf8739d0] [c00800000f3985dc] kvm_put_kvm+0x204/0x500 [kvm] [c000003fdf873a60] [c00800000f398910] kvm_vm_release+0x38/0x60 [kvm] [c000003fdf873a90] [c0000000004345fc] __fput+0xcc/0x2f0 [c000003fdf873af0] [c000000000139318] task_work_run+0x108/0x150 [c000003fdf873b30] [c000000000109408] do_exit+0x438/0xe10 [c000003fdf873c00] [c000000000109eb0] do_group_exit+0x60/0xe0 [c000003fdf873c40] [c00000000011ea24] get_signal+0x1b4/0xce0 [c000003fdf873d30] [c000000000025ea8] do_notify_resume+0x1a8/0x430 [c000003fdf873e20] [c00000000000e444] ret_from_except_lite+0x70/0x74 Instruction dump: ebc1fff0 ebe1fff8 7c0803a6 4e800020 60000000 60000000 3880ffff 38634630 4800df59 e8410018 2fa30000 409eff44 <0fe00000> 4bffff3c 7c0802a6 60000000 irq event stamp: 114938 hardirqs last enabled at (114937): [<c0000000003ab8f4>] free_unref_page+0xd4/0x100 hardirqs last disabled at (114938): [<c000000000009060>] program_check_common+0x170/0x180 softirqs last enabled at (114424): [<c000000000a06bdc>] peernet2id+0x6c/0xb0 softirqs last disabled at (114422): [<c000000000a06bb4>] peernet2id+0x44/0xb0 ---[ end trace c33c9599a1a73dd2 ]--- systemd-journald[1278]: Compressed data object 650 -> 280 using XZ tun: Universal TUN/TAP device driver, 1.6 virbr0: port 1(virbr0-nic) entered blocking state -- Alexey
