I do get get the same backtrace in gdb every time every time when we reproduce the hang:
(gdb) thread apply all bt Thread 9 (Thread 0x7fd1415ff700 (LWP 3202)): #0 0x00007fd323d154bf in __GI___poll (fds=0x7fd1415fe6c0, nfds=2, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29 #1 0x00007fd324978bb2 in ?? () from target:/lib/x86_64-linux-gnu/libusb-1.0.so.0 #2 0x00007fd323defea7 in start_thread (arg=<optimized out>) at pthread_create.c:477 #3 0x00007fd323d1feaf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 8 (Thread 0x7fd1437fe700 (LWP 3171)): #0 0x00007fd323d16d87 in ioctl () at ../sysdeps/unix/syscall-template.S:120 #1 0x000055a5daef74f7 in kvm_vcpu_ioctl () #2 0x000055a5daef7631 in kvm_cpu_exec () #3 0x000055a5daedaede in ?? () #4 0x000055a5db32194b in ?? () #5 0x00007fd323defea7 in start_thread (arg=<optimized out>) at pthread_create.c:477 #6 0x00007fd323d1feaf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 7 (Thread 0x7fd143fff700 (LWP 3170)): #0 0x00007fd323d16d87 in ioctl () at ../sysdeps/unix/syscall-template.S:120 #1 0x000055a5daef74f7 in kvm_vcpu_ioctl () #2 0x000055a5daef7631 in kvm_cpu_exec () #3 0x000055a5daedaede in ?? () #4 0x000055a5db32194b in ?? () #5 0x00007fd323defea7 in start_thread (arg=<optimized out>) at pthread_create.c:477 #6 0x00007fd323d1feaf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 6 (Thread 0x7fd150dfd700 (LWP 3169)): #0 __lll_lock_wait (futex=futex@entry=0x55a5db80a540, private=0) at lowlevellock.c:52 #1 0x00007fd323df2843 in __GI___pthread_mutex_lock (mutex=0x55a5db80a540) at ../nptl/pthread_mutex_lock.c:80 #2 0x000055a5db321b43 in qemu_mutex_lock_impl () #3 0x000055a5daedac8e in qemu_mutex_lock_iothread_impl () #4 0x000055a5dae92ac9 in ?? () #5 0x000055a5dae97de7 in flatview_read_continue () #6 0x000055a5dae98023 in ?? () #7 0x000055a5dae9813b in address_space_read_full () #8 0x000055a5daef78cf in kvm_cpu_exec () #9 0x000055a5daedaede in ?? () #10 0x000055a5db32194b in ?? () #11 0x00007fd323defea7 in start_thread (arg=<optimized out>) at pthread_create.c:477 #12 0x00007fd323d1feaf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 5 (Thread 0x7fd1515fe700 (LWP 3168)): #0 __lll_lock_wait (futex=futex@entry=0x55a5db80a540, private=0) at lowlevellock.c:52 #1 0x00007fd323df2843 in __GI___pthread_mutex_lock (mutex=0x55a5db80a540) at ../nptl/pthread_mutex_lock.c:80 #2 0x000055a5db321b43 in qemu_mutex_lock_impl () #3 0x000055a5daedac8e in qemu_mutex_lock_iothread_impl () #4 0x000055a5dae92ac9 in ?? () #5 0x000055a5dae97de7 in flatview_read_continue () #6 0x000055a5dae98023 in ?? () #7 0x000055a5dae9813b in address_space_read_full () #8 0x000055a5daef78cf in kvm_cpu_exec () #9 0x000055a5daedaede in ?? () #10 0x000055a5db32194b in ?? () #11 0x00007fd323defea7 in start_thread (arg=<optimized out>) at pthread_create.c:477 #12 0x00007fd323d1feaf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 4 (Thread 0x7fd151dff700 (LWP 3167)): #0 __lll_lock_wait (futex=futex@entry=0x55a5db80a540, private=0) at lowlevellock.c:52 #1 0x00007fd323df2843 in __GI___pthread_mutex_lock (mutex=0x55a5db80a540) at ../nptl/pthread_mutex_lock.c:80 --Type <RET> for more, q to quit, c to continue without paging-- #2 0x000055a5db321b43 in qemu_mutex_lock_impl () #3 0x000055a5daedac8e in qemu_mutex_lock_iothread_impl () #4 0x000055a5dae92ac9 in ?? () #5 0x000055a5dae97de7 in flatview_read_continue () #6 0x000055a5dae98023 in ?? () #7 0x000055a5dae9813b in address_space_read_full () #8 0x000055a5daef78cf in kvm_cpu_exec () #9 0x000055a5daedaede in ?? () #10 0x000055a5db32194b in ?? () #11 0x00007fd323defea7 in start_thread (arg=<optimized out>) at pthread_create.c:477 #12 0x00007fd323d1feaf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 3 (Thread 0x7fd320d97700 (LWP 3166)): #0 0x00007fd323d154bf in __GI___poll (fds=0x7fd318003180, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29 #1 0x00007fd324a097ee in ?? () from target:/lib/x86_64-linux-gnu/libglib-2.0.so.0 #2 0x00007fd324a09b53 in g_main_loop_run () from target:/lib/x86_64-linux-gnu/libglib-2.0.so.0 #3 0x000055a5db016c71 in ?? () #4 0x000055a5db32194b in ?? () #5 0x00007fd323defea7 in start_thread (arg=<optimized out>) at pthread_create.c:477 #6 0x00007fd323d1feaf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 2 (Thread 0x7fd3224de700 (LWP 3156)): #0 syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38 #1 0x000055a5db3226fa in qemu_event_wait () #2 0x000055a5db33466a in ?? () #3 0x000055a5db32194b in ?? () #4 0x00007fd323defea7 in start_thread (arg=<optimized out>) at pthread_create.c:477 #5 0x00007fd323d1feaf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 1 (Thread 0x7fd3224dff40 (LWP 3148)): #0 0x00007fd323d154bf in __GI___poll (fds=0x55a5dca30150, nfds=3, timeout=3) at ../sysdeps/unix/sysv/linux/poll.c:29 #1 0x00007fd324971f4d in ?? () from target:/lib/x86_64-linux-gnu/libusb-1.0.so.0 #2 0x00007fd32497316c in libusb_handle_events_timeout_completed () from target:/lib/x86_64-linux-gnu/libusb-1.0.so.0 #3 0x000055a5db18edc7 in ?? () #4 0x000055a5db18efab in ?? () #5 0x000055a5db31abf7 in aio_bh_poll () #6 0x000055a5db31e3fe in aio_dispatch () #7 0x000055a5db31aace in ?? () #8 0x00007fd324a095fd in g_main_context_dispatch () from target:/lib/x86_64-linux-gnu/libglib-2.0.so.0 #9 0x000055a5db31d638 in main_loop_wait () #10 0x000055a5dafad309 in qemu_main_loop () #11 0x000055a5dae9125e in main () (gdb) -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1884684 Title: QEMU 5.0: Guest VM hangs/freeze when unplugging USB device Status in QEMU: New Bug description: Setup: Host: Debian/SID, Kernel 5.6, QEMU 5.0 Guest: Windows 10 VM with PCI and USB device passthrough. Problem: Guest VM suddenly hangs when pulling USB device out from the Host. Observations: - Issue appears to be related to QEMU 5.0 - It started after an upgrade to QEMU 5.0. - Downgrading only QEMU on multiple systems fixes the issue. - Issue is very reproducible. - Most of the time within a few attempts of pulling/reconnecting the device. - Issue happens with multiple devices (I did try standard HID devices, a webcam and an x-ray sensor). - Guest just hangs. - Display output remains on last frame shown. - Ping to Guest immediately stops working. - Logs in the Guest stop logging immediately. - Host is fine and thinks the Guest is fine. - Guest continues to show as running in "virsh list". - No suspicious entries in the QEMU logs. - No suspicious entries in Host syslogs/messages. - Host can can kill guest "virsh destroy" and respawn fine. - Issue seems widespread. - Multiple similar reports from ProxMox users after upgrade to ProxMox 6.2 for both Windows and Linux guests (First version that uses QEMU 5.0) https://forum.proxmox.com/threads/vm-freezes-when-disconnecting-usb-keyboard-and-mouse.70287/ https://forum.proxmox.com/threads/usb-drive-crashes-vm.70214/ https://forum.proxmox.com/threads/latest-proxmox-usb-disconnects-freeze-kvm.70398/ https://forum.proxmox.com/threads/vm-with-gpu-passthrough-freezes-when-turning-off-monitor-after-proxmox-6-2-upgrade.69821/ https://forum.proxmox.com/threads/vm-with-gpu-passthrough-freezes-when-turning-off-monitor-after-proxmox-6-2-upgrade.69824/ I'd be more than happy any debugs that might be helpful. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1884684/+subscriptions
