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Re: [PULL v2 31/82] vhost: Change the sequence of device start
From: |
Michael S. Tsirkin |
Subject: |
Re: [PULL v2 31/82] vhost: Change the sequence of device start |
Date: |
Mon, 7 Nov 2022 08:30:32 -0500 |
On Sun, Nov 06, 2022 at 07:00:33PM +0100, Christian A. Ehrhardt wrote:
>
> Hi,
>
> On Sat, Nov 05, 2022 at 12:43:05PM -0400, Michael S. Tsirkin wrote:
> > On Sat, Nov 05, 2022 at 05:35:57PM +0100, Bernhard Beschow wrote:
> > >
> > >
> > > On Wed, Nov 2, 2022 at 5:24 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > >
> > > From: Yajun Wu <yajunw@nvidia.com>
> > >
> > > This patch is part of adding vhost-user vhost_dev_start support. The
> > > motivation is to improve backend configuration speed and reduce live
> > > migration VM downtime.
> > >
> > > Moving the device start routines after finishing all the necessary
> > > device
> > > and VQ configuration, further aligning to the virtio specification for
> > > "device initialization sequence".
> > >
> > > Following patch will add vhost-user vhost_dev_start support.
> > >
> > > Signed-off-by: Yajun Wu <yajunw@nvidia.com>
> > > Acked-by: Parav Pandit <parav@nvidia.com>
> > >
> > > Message-Id: <20221017064452.1226514-2-yajunw@nvidia.com>
> > > Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > ---
> > > hw/block/vhost-user-blk.c | 18 +++++++++++-------
> > > hw/net/vhost_net.c | 12 ++++++------
> > > 2 files changed, 17 insertions(+), 13 deletions(-)
> > >
> > >
> > > A git bisect tells me that this is the first bad commit for failing
> > > qos-tests
> > > which only fail when parallel jobs are enabled, e.g. `make check-qtest
> > > -j8`:
>
> Parallel test run is not required provided that the test machine is
> sufficiently busy (load > number of CPU threads). In this case a single
> invocation of the qos test will fail reliably with this change.
>
> However, the change is not really the root cause of the failures.
>
> > > Summary of Failures:
> > >
> > > 76/541 qemu:qtest+qtest-aarch64 / qtest-aarch64/qos-test
> > >
> > > ERROR 18.68s killed by signal 6 SIGABRT
> > > 77/541 qemu:qtest+qtest-arm / qtest-arm/qos-test
> > >
> > > ERROR 17.60s killed by signal 6 SIGABRT
> > > 93/541 qemu:qtest+qtest-i386 / qtest-i386/qos-test
> > >
> > > ERROR 18.98s killed by signal 6 SIGABRT
> > > 108/541 qemu:qtest+qtest-ppc64 / qtest-ppc64/qos-test
> > >
> > > ERROR 16.40s killed by signal 6 SIGABRT
> > > 112/541 qemu:qtest+qtest-i386 / qtest-i386/bios-tables-test
> > >
> > > ERROR 145.94s killed by signal 6 SIGABRT
> > > 130/541 qemu:qtest+qtest-x86_64 / qtest-x86_64/qos-test
> > >
> > > ERROR 17.32s killed by signal 6 SIGABRT
> > > 243/541 qemu:qtest+qtest-x86_64 / qtest-x86_64/bios-tables-test
> > >
> > > ERROR 127.70s killed by signal 6 SIGABRT
> > >
> > > Ok: 500
> > > Expected Fail: 0
> > > Fail: 7
> > > Unexpected Pass: 0
> > > Skipped: 34
> > > Timeout: 0
> > >
> > > Can anyone else reproduce this?
> >
> > Could you pls try latest for_upstream in my tree?
> > That should have this fixed.
>
> Your new pull request simply drops this change and this does fix
> make check-qtest. However, this looks accidental to me and the real
> bug is there in plain origin/master, too.
>
> What happens is this backtrace a recursive call to vu_gpio_stop
> via the backtrace below. It is caused by a delayed of the TCP
> connection (the delayed part only triggers with heavy load on the
> machine).
>
> You can get the failure back (probably in upstream) if the test is
> forced to us "use-started=off" which can be set on the command line.
> E.g. like this:
>
> diff --git a/tests/qtest/libqos/virtio-gpio.c
> b/tests/qtest/libqos/virtio-gpio.c
> index 762aa6695b..17c6b71e8b 100644
> --- a/tests/qtest/libqos/virtio-gpio.c
> +++ b/tests/qtest/libqos/virtio-gpio.c
> @@ -154,14 +154,14 @@ static void virtio_gpio_register_nodes(void)
> QOSGraphEdgeOptions edge_opts = { };
>
> /* vhost-user-gpio-device */
> - edge_opts.extra_device_opts = "id=gpio0,chardev=chr-vhost-user-test";
> + edge_opts.extra_device_opts =
> "id=gpio0,chardev=chr-vhost-user-test,use-started=off";
> qos_node_create_driver("vhost-user-gpio-device",
> virtio_gpio_device_create);
> qos_node_consumes("vhost-user-gpio-device", "virtio-bus", &edge_opts);
> qos_node_produces("vhost-user-gpio-device", "vhost-user-gpio");
>
> /* virtio-gpio-pci */
> - edge_opts.extra_device_opts =
> "id=gpio0,addr=04.0,chardev=chr-vhost-user-test";
> + edge_opts.extra_device_opts =
> "id=gpio0,addr=04.0,chardev=chr-vhost-user-test,use-started=on";
> add_qpci_address(&edge_opts, &addr);
> qos_node_create_driver("vhost-user-gpio-pci", virtio_gpio_pci_create);
> qos_node_consumes("vhost-user-gpio-pci", "pci-bus", &edge_opts);
>
>
> I haven't verified this but from looking at the code other types of
> vhost devices seem to have the same problem (e.g. vhost-user-i2c looks
> suspicious).
>
> Ok, here's the backtrace:
>
> #0 vu_gpio_stop (vdev=vdev@entry=0x560e0ae449d0) at
> ../hw/virtio/vhost-user-gpio.c:143
> #1 0x0000560e0768fb1f in vu_gpio_disconnect (dev=<optimized out>) at
> ../hw/virtio/vhost-user-gpio.c:260
> #2 vu_gpio_event (opaque=<optimized out>, event=<optimized out>) at
> ../hw/virtio/vhost-user-gpio.c:279
> #3 0x0000560e078057b5 in tcp_chr_disconnect_locked (chr=0x560e0a00f800) at
> ../chardev/char-socket.c:470
> #4 0x0000560e078058d3 in tcp_chr_write (chr=0x560e0a00f800, buf=<optimized
> out>, len=<optimized out>) at ../chardev/char-socket.c:129
> #5 0x0000560e07808a63 in qemu_chr_write_buffer (s=s@entry=0x560e0a00f800,
> buf=buf@entry=0x7ffc76812ac0 <error: Cannot access memory at address
> 0x7ffc76812ac0>, len=20, offset=offset@entry=0x7ffc76812a40,
> write_all=write_all@entry=true) at ../chardev/char.c:121
> #6 0x0000560e07808e84 in qemu_chr_write (s=0x560e0a00f800,
> buf=buf@entry=0x7ffc76812ac0 <error: Cannot access memory at address
> 0x7ffc76812ac0>, len=len@entry=20, write_all=write_all@entry=true) at
> ../chardev/char.c:173
> #7 0x0000560e078010e6 in qemu_chr_fe_write_all (be=be@entry=0x560e0ae44bc0,
> buf=buf@entry=0x7ffc76812ac0 <error: Cannot access memory at address
> 0x7ffc76812ac0>, len=len@entry=20) at ../chardev/char-fe.c:53
> #8 0x0000560e07676d16 in vhost_user_write (msg=msg@entry=0x7ffc76812ac0,
> fds=fds@entry=0x0, fd_num=fd_num@entry=0, dev=<optimized out>, dev=<optimized
> out>) at ../hw/virtio/vhost-user.c:490
> #9 0x0000560e076777c0 in vhost_user_get_vring_base (dev=0x560e0ae44c08,
> ring=0x7ffc76812d80) at ../hw/virtio/vhost-user.c:1260
> #10 0x0000560e0767314e in vhost_virtqueue_stop (dev=dev@entry=0x560e0ae44c08,
> vdev=vdev@entry=0x560e0ae449d0, vq=0x560e0ae7a570, idx=0) at
> ../hw/virtio/vhost.c:1220
> #11 0x0000560e07675236 in vhost_dev_stop (hdev=hdev@entry=0x560e0ae44c08,
> vdev=vdev@entry=0x560e0ae449d0) at ../hw/virtio/vhost.c:1884
> #12 0x0000560e0768f2fd in vu_gpio_stop (vdev=0x560e0ae449d0) at
> ../hw/virtio/vhost-user-gpio.c:148
> #13 0x0000560e0766a6a3 in virtio_set_status (vdev=0x560e0ae449d0,
> val=<optimized out>) at ../hw/virtio/virtio.c:2442
> #14 0x0000560e0751a2e0 in vm_state_notify (running=running@entry=false,
> state=state@entry=RUN_STATE_SHUTDOWN) at ../softmmu/runstate.c:334
> #15 0x0000560e07514d70 in do_vm_stop (send_stop=false,
> state=RUN_STATE_SHUTDOWN) at ../softmmu/cpus.c:262
> #16 vm_shutdown () at ../softmmu/cpus.c:280
> #17 0x0000560e0751af63 in qemu_cleanup () at ../softmmu/runstate.c:827
> #18 0x0000560e07350f33 in qemu_default_main () at ../softmmu/main.c:38
> #19 0x00007f0a5655bd90 in __libc_start_call_main
> (main=main@entry=0x560e0734c3e0 <main>, argc=argc@entry=25,
> argv=argv@entry=0x7ffc768130a8) at ../sysdeps/nptl/libc_start_call_main.h:58
> #20 0x00007f0a5655be40 in __libc_start_main_impl (main=0x560e0734c3e0 <main>,
> argc=25, argv=0x7ffc768130a8, init=<optimized out>, fini=<optimized out>,
> rtld_fini=<optimized out>, stack_end=0x7ffc76813098) at
> ../csu/libc-start.c:392
> #21 0x0000560e07350e55 in _start ()
>
>
> Any Ideas how to fix this properly?
>
> regards Christian
so fundamentally, any write into a socket can trigger stop?
I don't think we realized this.
Hmm this needs some thought there are likely more issues
like this.
--
MST