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[Qemu-devel] [Bug 1805256] Re: qemu-img hangs on rcu_call_ready_event lo
From: |
Rafael David Tinoco |
Subject: |
[Qemu-devel] [Bug 1805256] Re: qemu-img hangs on rcu_call_ready_event logic in Aarch64 when converting images |
Date: |
Wed, 11 Sep 2019 02:17:15 -0000 |
In comment #14, please disregard the second half of the issue, related
to:
0x0000aaaaaabd4100 <+16>: cbz w1, 0xaaaaaabd4108 <qemu_event_reset+24>
0x0000aaaaaabd4104 <+20>: ret
0x0000aaaaaabd4108 <+24>: ldaxr w1, [x0]
0x0000aaaaaabd410c <+28>: orr w1, w1, #0x1
=> 0x0000aaaaaabd4110 <+32>: stlxr w2, w1, [x0]
0x0000aaaaaabd4114 <+36>: cbnz w2, 0xaaaaaabd4108
Duh! This is just a regular load/xor/store logic for atomic_or() inside
qemu_event_reset().
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https://bugs.launchpad.net/bugs/1805256
Title:
qemu-img hangs on rcu_call_ready_event logic in Aarch64 when
converting images
Status in QEMU:
In Progress
Status in qemu package in Ubuntu:
In Progress
Bug description:
On the HiSilicon D06 system - a 96 core NUMA arm64 box - qemu-img
frequently hangs (~50% of the time) with this command:
qemu-img convert -f qcow2 -O qcow2 /tmp/cloudimg /tmp/cloudimg2
Where "cloudimg" is a standard qcow2 Ubuntu cloud image. This
qcow2->qcow2 conversion happens to be something uvtool does every time
it fetches images.
Once hung, attaching gdb gives the following backtrace:
(gdb) bt
#0 0x0000ffffae4f8154 in __GI_ppoll (fds=0xaaaae8a67dc0,
nfds=187650274213760,
timeout=<optimized out>, timeout@entry=0x0, sigmask=0xffffc123b950)
at ../sysdeps/unix/sysv/linux/ppoll.c:39
#1 0x0000aaaabbefaf00 in ppoll (__ss=0x0, __timeout=0x0, __nfds=<optimized
out>,
__fds=<optimized out>) at /usr/include/aarch64-linux-gnu/bits/poll2.h:77
#2 qemu_poll_ns (fds=<optimized out>, nfds=<optimized out>,
timeout=timeout@entry=-1) at util/qemu-timer.c:322
#3 0x0000aaaabbefbf80 in os_host_main_loop_wait (timeout=-1)
at util/main-loop.c:233
#4 main_loop_wait (nonblocking=<optimized out>) at util/main-loop.c:497
#5 0x0000aaaabbe2aa30 in convert_do_copy (s=0xffffc123bb58) at
qemu-img.c:1980
#6 img_convert (argc=<optimized out>, argv=<optimized out>) at
qemu-img.c:2456
#7 0x0000aaaabbe2333c in main (argc=7, argv=<optimized out>) at
qemu-img.c:4975
Reproduced w/ latest QEMU git (@ 53744e0a182)
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