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Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop |
Date: |
Mon, 21 Mar 2016 17:42:06 +0800 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, 03/18 16:03, Paolo Bonzini wrote:
>
>
> On 17/03/2016 17:08, Christian Borntraeger wrote:
> > Good (or bad?) news is the assert also triggers on F23, it just seems
> > to take longer.
>
> I guess good news, because we can rule out the kernel (not that I
> believed it was a kernel problem, but the thought is always there in
> the background...).
>
> The interaction between ioeventfd and dataplane is too complicated. I
> think if we get rid of the start/stop ioeventfd calls (just set up the
> ioeventfd as soon as possible and then only set/clear the handlers)
> things would be much simpler.
>
> I'll see if I can produce something based on Conny's patches, which are
> already a start. Today I had a short day so I couldn't play with the
> bug; out of curiosity, does the bug reproduce with her work + patch 4
> from this series + the reentrancy assertion?
The other half of the race condition is from ioport write in the vcpu thread. I
hit this by adding an extra assert(is_in_iothread()) in
virtio_blk_handle_request(), at the same place with Paolo's atomic read of
variable "test".
I haven't tried to find where this ioport write is from, but that is indeed an
issue in virtio-pci.
(gdb) thread apply all bt
<...>
Thread 3 (Thread 0x7f9e8928b700 (LWP 30671)):
#0 0x00007f9e8bac65d7 in __GI_raise (address@hidden) at
../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1 0x00007f9e8bac7cc8 in __GI_abort () at abort.c:90
#2 0x00007f9e8babf546 in __assert_fail_base (fmt=0x7f9e8bc0f128 "%s%s%s:%u:
%s%sAssertion `%s' failed.\n%n", address@hidden "is_in_iothread()",
address@hidden "/home/fam/work/qemu/hw/block/virtio-blk.c", address@hidden,
address@hidden <__PRETTY_FUNCTION__.37148> "virtio_blk_handle_output") at
assert.c:92
#3 0x00007f9e8babf5f2 in __GI___assert_fail (assertion=0x7f9e8e04e9d1
"is_in_iothread()", file=0x7f9e8e04e8e0
"/home/fam/work/qemu/hw/block/virtio-blk.c", line=597,
function=0x7f9e8e04ec30 <__PRETTY_FUNCTION__.37148>
"virtio_blk_handle_output") at assert.c:101
#4 0x00007f9e8dc9f414 in virtio_blk_handle_output (vdev=0x7f9e929d7b68,
vq=0x7f9e92a762f0) at /home/fam/work/qemu/hw/block/virtio-blk.c:597
#5 0x00007f9e8dcd6f53 in virtio_queue_notify_vq (vq=0x7f9e92a762f0) at
/home/fam/work/qemu/hw/virtio/virtio.c:1095
#6 0x00007f9e8dcd6f91 in virtio_queue_notify (vdev=0x7f9e929d7b68, n=0) at
/home/fam/work/qemu/hw/virtio/virtio.c:1101
#7 0x00007f9e8df03d2f in virtio_ioport_write (opaque=0x7f9e929cf840, addr=16,
val=0) at /home/fam/work/qemu/hw/virtio/virtio-pci.c:419
#8 0x00007f9e8df041be in virtio_pci_config_write (opaque=0x7f9e929cf840,
addr=16, val=0, size=2) at /home/fam/work/qemu/hw/virtio/virtio-pci.c:552
#9 0x00007f9e8dc7c8c9 in memory_region_write_accessor (mr=0x7f9e929d00c0,
addr=16, value=0x7f9e8928a988, size=2, shift=0, mask=65535, attrs=...)
at /home/fam/work/qemu/memory.c:524
#10 0x00007f9e8dc7cad4 in access_with_adjusted_size (addr=16,
value=0x7f9e8928a988, size=2, access_size_min=1, access_size_max=4, access=
0x7f9e8dc7c7e8 <memory_region_write_accessor>, mr=0x7f9e929d00c0,
attrs=...) at /home/fam/work/qemu/memory.c:590
#11 0x00007f9e8dc7f71b in memory_region_dispatch_write (mr=0x7f9e929d00c0,
addr=16, data=0, size=2, attrs=...) at /home/fam/work/qemu/memory.c:1272
#12 0x00007f9e8dc32815 in address_space_write_continue (as=0x7f9e8e5834a0
<address_space_io>, addr=49232, attrs=..., buf=0x7f9e8daa9000 <Address
0x7f9e8daa9000 out of bounds>,
len=2, addr1=16, l=2, mr=0x7f9e929d00c0) at /home/fam/work/qemu/exec.c:2607
#13 0x00007f9e8dc329c1 in address_space_write (as=0x7f9e8e5834a0
<address_space_io>, addr=49232, attrs=..., buf=0x7f9e8daa9000 <Address
0x7f9e8daa9000 out of bounds>, len=2)
at /home/fam/work/qemu/exec.c:2659
#14 0x00007f9e8dc32d78 in address_space_rw (as=0x7f9e8e5834a0
<address_space_io>, addr=49232, attrs=..., buf=0x7f9e8daa9000 <Address
0x7f9e8daa9000 out of bounds>, len=2,
is_write=true) at /home/fam/work/qemu/exec.c:2762
#15 0x00007f9e8dc79358 in kvm_handle_io (port=49232, attrs=...,
data=0x7f9e8daa9000, direction=1, size=2, count=1) at
/home/fam/work/qemu/kvm-all.c:1699
#16 0x00007f9e8dc79858 in kvm_cpu_exec (cpu=0x7f9e905a5250) at
/home/fam/work/qemu/kvm-all.c:1863
#17 0x00007f9e8dc619a3 in qemu_kvm_cpu_thread_fn (arg=0x7f9e905a5250) at
/home/fam/work/qemu/cpus.c:1056
#18 0x00007f9e8be59df5 in start_thread (arg=0x7f9e8928b700) at
pthread_create.c:308
#19 0x00007f9e8bb871ad in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:113
<...>
Thread 1 (Thread 0x7f9e8b28f700 (LWP 30667)):
#0 0x00007f9e8bac65d7 in __GI_raise (address@hidden) at
../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1 0x00007f9e8bac7cc8 in __GI_abort () at abort.c:90
#2 0x00007f9e8babf546 in __assert_fail_base (fmt=0x7f9e8bc0f128 "%s%s%s:%u:
%s%sAssertion `%s' failed.\n%n", address@hidden "x == 0",
address@hidden "/home/fam/work/qemu/hw/block/virtio-blk.c", address@hidden,
address@hidden <__PRETTY_FUNCTION__.37148> "virtio_blk_handle_output") at
assert.c:92
#3 0x00007f9e8babf5f2 in __GI___assert_fail (assertion=0x7f9e8e04e9e2 "x ==
0", file=0x7f9e8e04e8e0 "/home/fam/work/qemu/hw/block/virtio-blk.c", line=598,
function=0x7f9e8e04ec30 <__PRETTY_FUNCTION__.37148>
"virtio_blk_handle_output") at assert.c:101
#4 0x00007f9e8dc9f43c in virtio_blk_handle_output (vdev=0x7f9e929d7b68,
vq=0x7f9e92a762f0) at /home/fam/work/qemu/hw/block/virtio-blk.c:598
#5 0x00007f9e8dcd6f53 in virtio_queue_notify_vq (vq=0x7f9e92a762f0) at
/home/fam/work/qemu/hw/virtio/virtio.c:1095
#6 0x00007f9e8dcd8dfd in virtio_queue_host_notifier_read (n=0x7f9e92a76348) at
/home/fam/work/qemu/hw/virtio/virtio.c:1785
#7 0x00007f9e8df76b40 in aio_dispatch (ctx=0x7f9e90540a50) at
/home/fam/work/qemu/aio-posix.c:327
#8 0x00007f9e8df770f8 in aio_poll (ctx=0x7f9e90540a50, blocking=true) at
/home/fam/work/qemu/aio-posix.c:475
#9 0x00007f9e8dd7b5c4 in iothread_run (opaque=0x7f9e905404d0) at
/home/fam/work/qemu/iothread.c:55
#10 0x00007f9e8be59df5 in start_thread (arg=0x7f9e8b28f700) at
pthread_create.c:308
#11 0x00007f9e8bb871ad in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:113
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, (continued)
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Fam Zheng, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, tu bo, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Paolo Bonzini, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/17
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Paolo Bonzini, 2016/03/18
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop,
Fam Zheng <=
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Christian Borntraeger, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, TU BO, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Paolo Bonzini, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Fam Zheng, 2016/03/21
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/16
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Paolo Bonzini, 2016/03/16
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Cornelia Huck, 2016/03/16
- Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop, Paolo Bonzini, 2016/03/16