Re: [PATCH v4 05/12] aio: remove aio_context_use_g_source()

[Kevin Wolf <kwolf@redhat.com>]

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Am 21.10.2025 um 21:10 hat Stefan Hajnoczi geschrieben:
> On Thu, Oct 09, 2025 at 06:59:20PM +0200, Kevin Wolf wrote:
> > Am 09.10.2025 um 17:46 hat Kevin Wolf geschrieben:
> > > Am 10.09.2025 um 19:56 hat Stefan Hajnoczi geschrieben:
> > > > There is no need for aio_context_use_g_source() now that epoll(7) and
> > > > io_uring(7) file descriptor monitoring works with the glib event loop.
> > > > AioContext doesn't need to be notified that GSource is being used.
> > > > 
> > > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > > > Reviewed-by: Eric Blake <eblake@redhat.com>
> > > 
> > > We should probably mention in the commit message that this causes the
> > > default fdmon on Linux to change from poll to io_uring. It's a small
> > > code change, but it makes QEMU use a completely different code path by
> > > default.
> > 
> > Just to make sure, I ran 'make check' after this patch and it's failing
> > for me:
> > 
> >  10/401 qemu:qtest+qtest-x86_64 / qtest-x86_64/ahci-test                    TIMEOUT        150.02s   killed by signal 15 SIGTERM
> > 133/401 qemu:unit / test-aio                                                TIMEOUT         30.01s   killed by signal 15 SIGTERM
> > 137/401 qemu:unit / test-bdrv-drain                                         TIMEOUT         30.01s   killed by signal 15 SIGTERM
> > 142/401 qemu:unit / test-block-iothread                                     TIMEOUT         30.01s   killed by signal 15 SIGTERM
> > 192/401 qemu:doc+rust / rust-bql-rs-doctests                                FAIL             0.84s   exit status 101
> > 311/401 qemu:block / io-qcow2-267                                           ERROR            3.20s   exit status 1
> > 321/401 qemu:block / io-qcow2-copy-before-write                             TIMEOUT        180.01s   killed by signal 15 SIGTERM
> > 
> > Some of them look unrelated, but I have confirmed that the three unit
> > tests still pass before this patch (and still hang after the complete
> > series).
> 
> I can't reproduce these failures, regardless of whether sysctl
> kernel.io_uring_disabled is 0 or 1.
> 
> Can you launch the unit tests from your terminal and post the output?
> 
>   $ cd qemu
>   $ build/tests/unit/test-aio

TAP version 14
# random seed: R02S48dcdde28634143f18bad3947c52d334
1..27
# Start of aio tests
# Start of bh tests
ok 1 /aio/bh/schedule
ok 2 /aio/bh/schedule10
ok 3 /aio/bh/cancel
ok 4 /aio/bh/delete
ok 5 /aio/bh/flush
# Start of callback-delete tests
ok 6 /aio/bh/callback-delete/one
ok 7 /aio/bh/callback-delete/many
# End of callback-delete tests
# End of bh tests
# Start of event tests
ok 8 /aio/event/add-remove
ok 9 /aio/event/wait
ok 10 /aio/event/flush
# Start of wait tests
ok 11 /aio/event/wait/no-flush-cb
# End of wait tests
# End of event tests
# Start of timer tests

>   $ build/tests/unit/test-bdrv-drain

TAP version 14
# random seed: R02S7d6ba0fc81d5b90d323813d680a30644
1..30
# Start of bdrv-drain tests
ok 1 /bdrv-drain/nested
ok 2 /bdrv-drain/set_aio_context
# Start of driver-cb tests


>   $ build/tests/unit/test-block-iothread

TAP version 14
# random seed: R02Sf81baf68887daa9b86be5c72b99df589
1..22
# Start of sync-op tests
ok 1 /sync-op/pread
ok 2 /sync-op/pwrite
ok 3 /sync-op/preadv
ok 4 /sync-op/pwritev
ok 5 /sync-op/preadv_part
ok 6 /sync-op/pwritev_part
ok 7 /sync-op/pwrite_compressed
ok 8 /sync-op/pwrite_zeroes
ok 9 /sync-op/load_vmstate
ok 10 /sync-op/save_vmstate
ok 11 /sync-op/pdiscard
ok 12 /sync-op/truncate
ok 13 /sync-op/block_status
ok 14 /sync-op/flush
ok 15 /sync-op/check
ok 16 /sync-op/activate
# End of sync-op tests
# Start of attach tests

> That will show exactly which sub-test case is hanging.
> Other information that might help: your host kernel version and liburing
> version.

This is a F42 system.

kernel-6.16.12-200.fc42.x86_64
liburing-2.9-1.fc42.x86_64

If you can't reproduce or find a hypothesis what's happening, I can try
to debug one of the hanging processes.

Kevin

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