A third stack trace It generates the following stack trace --------------------------------------------------------------------- (gdb) bt #0 qemu_co_queue_run_restart (co=0x7f75ed30dbc0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:59 #1 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75ed30dbc0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #2 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75f1c0f200) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #3 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75f1c0f200) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #4 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75ed304870) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #5 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75ed304870) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #6 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e800fcd0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #7 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e800fcd0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #8 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e800fac0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #9 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e800fac0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #10 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e800f8b0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #11 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e800f8b0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #12 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75fbf05570) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #13 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75fbf05570) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #14 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e8009b70) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #15 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e8009b70) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #16 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e800b5d0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #17 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e800b5d0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #18 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e8008910) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #19 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e8008910) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #20 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e800f6a0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #21 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e800f6a0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #22 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75fbf05100) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #23 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75fbf05100) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #24 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75fbf04ee0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #25 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75fbf04ee0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #26 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75ed301c50) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #27 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75ed301c50) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #28 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75ed315270) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #29 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75ed315270) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #30 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75ed31cf10) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #31 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75ed31cf10) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #32 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e800a970) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #33 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e800a970) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #34 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e8007df0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #35 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e8007df0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #36 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e8005960) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #37 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e8005960) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #38 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e800e1b0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #39 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e800e1b0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #40 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e8000a00) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #41 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e8000a00) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #42 0x0000561927482e74 in qemu_co_queue_run_restart (co=0x7f75e8007900) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #43 0x00005619274829a9 in qemu_coroutine_enter (co=0x7f75e8007900) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #44 0x0000561927482fa0 in qemu_co_enter_next (queue=queue@entry=0x5619288d15e0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:106 #45 0x0000561927421060 in timer_cb (blk=0x5619288d1590, is_write=<optimized out>) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/block/throttle-groups.c:400 #46 0x00005619273de615 in timerlist_run_timers (timer_list=0x56192893de80) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/qemu-timer.c:528 #47 0x00005619273de679 in timerlistgroup_run_timers (tlg=tlg@entry=0x561929b6bcf8) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/qemu-timer.c:564 #48 0x00005619273def47 in aio_dispatch (ctx=ctx@entry=0x561929b6bbb0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/aio-posix.c:357 #49 0x00005619273df0e8 in aio_poll (ctx=0x561929b6bbb0, blocking=<optimized out>) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/aio-posix.c:479 #50 0x0000561927240c79 in iothread_run (opaque=0x561929b6b960) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/iothread.c:46 #51 0x00007f77b32160a4 in start_thread (arg=0x7f77997ff700) at pthread_create.c:403 #52 0x00007f77b2f4b62d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 ---------------------------------------------------------------------
It's also crashing in list traversal. Looking at the contained data we see: --------------------------------------------------------------------- (gdb) print *(&co->co_queue_wakeup->sqh_first) $1 = (struct Coroutine *) 0x1 (gdb) print *(&co->co_queue_wakeup->sqh_first->co_queue_next) Cannot access memory at address 0x31 --------------------------------------------------------------------- So again. Segfault is caused by apparently invalid addresses. And this time it occurs after so many invocations of qemu_co_queue_run_restart() -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1671876 Title: qemu 2.7.0 segfaults in qemu_co_queue_run_restart() Status in QEMU: New Bug description: Hi, I've been experiencing frequent segfaults lately with qemu 2.7.0 running Ubuntu 16.04 guests. The crash usually happens in qemu_co_queue_run_restart(). I haven't seen this so far with any other guests or distros. Here is one back trace I obtained from one of the crashing VMs. -------------------------------------------------------------------------- (gdb) bt #0 qemu_co_queue_run_restart (co=0x7fba8ff05aa0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:59 #1 0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba8ff05aa0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #2 0x000055c1656f3e74 in qemu_co_queue_run_restart (co=0x7fba8dd20430) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #3 0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba8dd20430) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #4 0x000055c1656f3e74 in qemu_co_queue_run_restart (co=0x7fba8dd14ea0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #5 0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba8dd14ea0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #6 0x000055c1656f3e74 in qemu_co_queue_run_restart (co=0x7fba80c11dc0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #7 0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba80c11dc0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #8 0x000055c1656f3e74 in qemu_co_queue_run_restart (co=0x7fba8dd0bd70) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:60 #9 0x000055c1656f39a9 in qemu_coroutine_enter (co=0x7fba8dd0bd70) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine.c:119 #10 0x000055c1656f3fa0 in qemu_co_enter_next (queue=queue@entry=0x55c1669e75e0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/util/qemu-coroutine-lock.c:106 #11 0x000055c165692060 in timer_cb (blk=0x55c1669e7590, is_write=<optimized out>) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/block/throttle-groups.c:400 #12 0x000055c16564f615 in timerlist_run_timers (timer_list=0x55c166a53e80) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/qemu-timer.c:528 #13 0x000055c16564f679 in timerlistgroup_run_timers (tlg=tlg@entry=0x55c167c81cf8) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/qemu-timer.c:564 #14 0x000055c16564ff47 in aio_dispatch (ctx=ctx@entry=0x55c167c81bb0) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/aio-posix.c:357 #15 0x000055c1656500e8 in aio_poll (ctx=0x55c167c81bb0, blocking=<optimized out>) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/aio-posix.c:479 #16 0x000055c1654b1c79 in iothread_run (opaque=0x55c167c81960) at /build/pb-qemu-pssKUp/pb-qemu-2.7.0/iothread.c:46 #17 0x00007fbc4b64f0a4 in allocate_stack (stack=<synthetic pointer>, pdp=<synthetic pointer>, attr=0x0) at allocatestack.c:416 #18 __pthread_create_2_1 (newthread=<error reading variable: Cannot access memory at address 0xffffffffffffff48>, attr=<error reading variable: Cannot access memory at address 0xffffffffffffff40>, start_routine=<error reading variable: Cannot access memory at address 0xffffffffffffff58>, arg=<error reading variable: Cannot access memory at address 0xffffffffffffff50>) at pthread_create.c:539 Backtrace stopped: Cannot access memory at address 0x8 -------------------------------------------------------------------------- The code that crashes is this -------------------------------------------------------------------------- void qemu_co_queue_run_restart(Coroutine *co) { Coroutine *next; trace_qemu_co_queue_run_restart(co); while ((next = QSIMPLEQ_FIRST(&co->co_queue_wakeup))) { QSIMPLEQ_REMOVE_HEAD(&co->co_queue_wakeup, co_queue_next); <--- Crash occurs here this time qemu_coroutine_enter(next); } } -------------------------------------------------------------------------- Expanding the macro QSIMPLEQ_REMOVE_HEAD gives us -------------------------------------------------------------------------- #define QSIMPLEQ_REMOVE_HEAD(head, field) do { \ if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL)\ (head)->sqh_last = &(head)->sqh_first; \ } while (/*CONSTCOND*/0) -------------------------------------------------------------------------- which corrsponds to -------------------------------------------------------------------------- if (((&co->co_queue_wakeup)->sqh_first = (&co->co_queue_wakeup)->sqh_first->co_queue_next.sqe_next) == NULL)\ (&co->co_queue_wakeup)->sqh_last = &(&co->co_queue_wakeup)->sqh_first; -------------------------------------------------------------------------- Debugging the list we see -------------------------------------------------------------------------- (gdb) print *(&co->co_queue_wakeup->sqh_first) $6 = (struct Coroutine *) 0x1000 (gdb) print *(&co->co_queue_wakeup->sqh_first->co_queue_next) Cannot access memory at address 0x1030 -------------------------------------------------------------------------- So the data in co->co_queue_wakeup->sqh_first is corrupted and represents an invalid address. Any idea why is that? To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1671876/+subscriptions