diff options
Diffstat (limited to 'gitlab/issues_text/target_missing/host_missing/accel_missing/764')
| -rw-r--r-- | gitlab/issues_text/target_missing/host_missing/accel_missing/764 | 45 |
1 files changed, 0 insertions, 45 deletions
diff --git a/gitlab/issues_text/target_missing/host_missing/accel_missing/764 b/gitlab/issues_text/target_missing/host_missing/accel_missing/764 deleted file mode 100644 index fce227518..000000000 --- a/gitlab/issues_text/target_missing/host_missing/accel_missing/764 +++ /dev/null @@ -1,45 +0,0 @@ -qemu-system-x86 crash (reason: use after free in socket_reconnect_timeout when reconnecting vhost-user dev) -Description of problem: -(gdb) bt<br/> -#0 0x00007f205976b78b in raise () from /usr/lib64/libc.so.6<br/> -#1 0x00007f205976cab1 in abort () from /usr/lib64/libc.so.6<br/> -#2 0x00007f205976404a in ?? () from /usr/lib64/libc.so.6<br/> -#3 0x00007f20597640c2 in __assert_fail () from /usr/lib64/libc.so.6<br/> -#4 0x00007f20594ea556 in **qemu_mutex_lock_impl**(mutex=<optimized out>, file=<optimized out>, line=<optimized out>)<br/> -#5 0x00007f205957a4ef in **socket_reconnect_timeout** (opaque=<optimized out>)<br/> -#6 0x00007f205993b68d in ?? () from /usr/lib64/libglib-2.0.so.0<br/> -#7 0x00007f205993aba4 in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0<br/> -#8 0x00007f20594e5d49 in glib_pollfds_poll () at /usr/src/debug/qemu-4.1.0-666.x86_64/util/main-loop.c:218<br/> -#9 0x00007f20594e5dc2 in os_host_main_loop_wait (timeout=<optimized out>)<br/> -#10 0x00007f20594e5f5d in main_loop_wait (nonblocking=nonblocking@entry=0)<br/> -... ...<br/> -#14 0x0000560919e13180 in main (argc=80, argv=0x7ffebc1d0598, envp=0x7ffebc1d0820)<br/> - -at the moment, chr had be free by hot unplug vhost-user dev<br/> - -I think the bug cause reason as following:<br/> -1. when vhost-user dev is connecting state, io-task-worker thread will try call tcp_chr_connect_client_async <br/> - again and again to reconnect.<br/> -2. if reconnect fail, io-task-worker thread will switch to main-thread to handle error, and main-thread will <br/> -call qemu_chr_socket_restart_timer again to reconnect again. <br/> - -3. But, if a hot unplug operation insert to main-thread before io-task-worker switch to main-thread,<br/> - the qemu_chr_socket_restart_timer->socket_reconnect_timeout process will use the released chardev and <br/> - trigger qemu crash - -in short, the primary cause of this bug is io-task-worker reconnect process and <br/> -main-thread hot unplug vhost-user-dev process in a race.<br/> -Steps to reproduce: -1. in qio_task_thread_worker func, add sleep in the following position: <br/> -  task->thread->completion = g_idle_source_new(); <br/> -  g_source_set_callback(task->thread->completion,<br/> - qio_task_thread_result, task, NULL);<br/> -  **sleep(8);**<br/> -  g_source_attach(task->thread->completion,<br/> - task->thread->context);<br/> -  g_source_unref(task->thread->completion); <br/> -2. kill spdk proces or dpdk process, qemu will reconnect to the disconnected vhost-user dev of spdk or dpdk <br/> -3. hot unplug the disconnected vhost-user dev when reconnect logic goto upper sleep position <br/> -4. qemu_chr_socket_restart_timer will use the chr after free, and trigger qemu crash -Additional information: - |