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[Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on a
From: |
贞贵李 |
Subject: |
[Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability |
Date: |
Sat, 20 Apr 2019 02:49:16 -0000 |
I can reproduce this problem with qemu.git/matser. It still exists in
qemu.git/matser. I found that when an IO return in
worker threads and want to call aio_notify to wake up main_loop, but it found
that ctx->notify_me is cleared to 0 by main_loop in aio_ctx_check by calling
atomic_and(&ctx->notify_me, ~1) . So worker thread won't write enventfd to
notify main_loop. If such a scene happens, the main_loop will hang:
main loop worker thread1
worker thread2
---------------------------------------------------------------------------------------------------------------------
qemu_poll_ns aio_worker
qemu_bh_schedule(pool->completion_bh)
glib_pollfds_poll
g_main_context_check
aio_ctx_check
aio_worker
atomic_and(&ctx->notify_me, ~1)
qemu_bh_schedule(pool->completion_bh)
/* do something for event */
qemu_poll_ns
/* hangs !!!*/
As we known ,ctx->notify_me will be visited by worker thread and main loop. I
thank we should add a lock protection for ctx->notify_me to avoid this happend.
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https://bugs.launchpad.net/bugs/1824053
Title:
Qemu-img convert appears to be stuck on aarch64 host with low
probability
Status in QEMU:
Confirmed
Bug description:
Hi, I found a problem that qemu-img convert appears to be stuck on
aarch64 host with low probability.
The convert command line is "qemu-img convert -f qcow2 -O raw
disk.qcow2 disk.raw ".
The bt is below:
Thread 2 (Thread 0x40000b776e50 (LWP 27215)):
#0 0x000040000a3f2994 in sigtimedwait () from /lib64/libc.so.6
#1 0x000040000a39c60c in sigwait () from /lib64/libpthread.so.0
#2 0x0000aaaaaae82610 in sigwait_compat (opaque=0xaaaac5163b00) at
util/compatfd.c:37
#3 0x0000aaaaaae85038 in qemu_thread_start (address@hidden) at
util/qemu_thread_posix.c:496
#4 0x000040000a3918bc in start_thread () from /lib64/libpthread.so.0
#5 0x000040000a492b2c in thread_start () from /lib64/libc.so.6
Thread 1 (Thread 0x40000b573370 (LWP 27214)):
#0 0x000040000a489020 in ppoll () from /lib64/libc.so.6
#1 0x0000aaaaaadaefc0 in ppoll (__ss=0x0, __timeout=0x0, __nfds=<optimized
out>, __fds=<optimized out>) at /usr/include/bits/poll2.h:77
#2 qemu_poll_ns (fds=<optimized out>, nfds=<optimized out>,
timeout=<optimized out>) at qemu_timer.c:391
#3 0x0000aaaaaadae014 in os_host_main_loop_wait (timeout=<optimized out>) at
main_loop.c:272
#4 0x0000aaaaaadae190 in main_loop_wait (nonblocking=<optimized out>) at
main_loop.c:534
#5 0x0000aaaaaad97be0 in convert_do_copy (s=0xffffdc32eb48) at
qemu-img.c:1923
#6 0x0000aaaaaada2d70 in img_convert (argc=<optimized out>, argv=<optimized
out>) at qemu-img.c:2414
#7 0x0000aaaaaad99ac4 in main (argc=7, argv=<optimized out>) at
qemu-img.c:5305
The problem seems to be very similar to the phenomenon described by this
patch
(https://resources.ovirt.org/pub/ovirt-4.1/src/qemu-kvm-ev/0025-aio_notify-force-main-loop-wakeup-with-SIGIO-aarch64.patch),
which force main loop wakeup with SIGIO. But this patch was reverted
by the patch (http://ovirt.repo.nfrance.com/src/qemu-kvm-ev/kvm-
Revert-aio_notify-force-main-loop-wakeup-with-SIGIO-.patch).
The problem still seems to exist in aarch64 host. The qemu version I used is
2.8.1. The host version is 4.19.28-1.2.108.aarch64.
Do you have any solutions to fix it? Thanks for your reply !
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- [Qemu-devel] [Bug 1824053] [NEW] Qemu-img convert appears to be stuck on aarch64 host with low probability, 贞贵李, 2019/04/09
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability, 贞贵李, 2019/04/12
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability, 贞贵李, 2019/04/15
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability, John Snow, 2019/04/15
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability, Thomas Huth, 2019/04/16
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability, 贞贵李, 2019/04/16
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability, Thomas Huth, 2019/04/16
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability, 贞贵李, 2019/04/19
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability,
贞贵李 <=
- [Qemu-devel] [Bug 1824053] Re: Qemu-img convert appears to be stuck on aarch64 host with low probability, 贞贵李, 2019/04/19