** Description changed:
+ [Impact]
+
+ It seems that kernel 6.8 introduced a regression in the 9pfs related to
+ caching and netfslib, that can cause some user-space apps to read
+ content from files that is not up-to-date (when they are used in a
+ producer/consumer fashion).
+
+ It seems that the offending commit is this one:
+
+ 80105ed2fd27 ("9p: Use netfslib read/write_iter")
+
+ Reverting the commit seems to fix the problem. However the actual bug
+ might be in netfslib or how netfslib is used in the 9p context.
+
+ The regression has been reported upstream and we are still investigating
+ (https://lore.kernel.org/lkml/Zj0ErxVBE3DYT2Ea@gpd/).
+
+ In the meantime it probably makes sense to temporarily revert the commit
+ as a SAUCE patch. Then we will drop the SAUCE patch once we'll have a
+ proper fix upstream.
+
+ [Test case]
+
+ The following test should complete correctly without any timeout:
+
+ pull-lp-source -d hello
+ autopkgtest-buildvm-ubuntu-cloud -r noble
+ autopkgtest -U hello*.dsc -- qemu ./autopkgtest-noble-amd64.img
+
+
+ [Fix]
+
+ Revert the following commit (until we have a proper fix upstream):
+
+ 80105ed2fd27 ("9p: Use netfslib read/write_iter")
+
+ [Regression potential]
+
+ We may experience other regressions related to 9pfs with this change,
+ however it's quite unlikely to happen since we are reverting a commit,
+ restoring the previous behavior.
+
+ [Original bug report]
+
autopkgtest-virt-qemu sometimes hangs when running tests on noble
images. Originally reported by schopin, who also provided a reproducer:
- pull-lp-source -d hello
- autopkgtest-buildvm-ubuntu-cloud -r noble
- autopkgtest -U hello*.dsc -- qemu ./autopkgtest-noble-amd64.img
+ pull-lp-source -d hello
+ autopkgtest-buildvm-ubuntu-cloud -r noble
+ autopkgtest -U hello*.dsc -- qemu ./autopkgtest-noble-amd64.img
I've been able to reproduce it with debugging enabled:
- autopkgtest -ddd -U hello_2.10-3.dsc -- qemu --debug --show-boot
+ autopkgtest -ddd -U hello_2.10-3.dsc -- qemu --debug --show-boot
/path/to/image
It can get stuck during different stages, but AFAICT always during
"copydown" operations, log excerpts follow. It may be a coincidence, but
this started happening around the time linux-image-6.8.0-11-generic
(6.8.0-11.11) migrated to noble. The testbeds I used booted 6.6 but then
rebooted into that 6.8 kernel after being upgraded by autopkgtest.
-- logs --
Removing autopkgtest-satdep (0) ...
[...]
autopkgtest-virt-qemu: DBG: executing copydown
/tmp/autopkgtest.output.g8v75e8g/tests-tree/ /t/
autopkgtest-virt-qemu: DBG: ['cmdls', "(['tar', '--directory',
'/tmp/autopkgtest.output.g8v75e]
autopkgtest-virt-qemu: DBG: ['srcstdin', "<_io.BufferedReader
name='/dev/null'>", 'deststdout']
autopkgtest-virt-qemu: DBG: +< tar --directory
/tmp/autopkgtest.output.g8v75e8g/tests-tree/ --
autopkgtest-virt-qemu: DBG: +> /tmp/autopkgtest-qemu.ztmr6f5k/runcmd sh -ec
if ! test -d /tmp-
autopkgtest-virt-qemu: DBG: +>?
-- or --
autopkgtest: DBG: sending command to testbed: copydown
/tmp/autopkgtest.output.c9utq3bx/tests-tree/
/tmp/autopkgtest.H8NDfW/build.DLR/src/
autopkgtest-virt-qemu: DBG: executing copydown
/tmp/autopkgtest.output.c9utq3bx/tests-tree/
/tmp/autopkgtest.H8NDfW/build.DLR/src/
autopkgtest-virt-qemu: DBG: ['cmdls', "(['tar', '--directory',
'/tmp/autopkgtest.output.c9utq3bx/tests-tree/', '--warning=none', '-c', '.',
'-f', '-'], ['/tmp/autopkgtest-qemu.qtkcgg5l/runcm]
autopkgtest-virt-qemu: DBG: ['srcstdin', "<_io.BufferedReader
name='/dev/null'>", 'deststdout', "<_io.BufferedReader name='/dev/null'>",
'devnull_read', <_io.BufferedReader name='/dev/null'>]
autopkgtest-virt-qemu: DBG: +< tar --directory
/tmp/autopkgtest.output.c9utq3bx/tests-tree/ --warning=none -c . -f -
autopkgtest-virt-qemu: DBG: +> /tmp/autopkgtest-qemu.qtkcgg5l/runcmd sh -ec
if ! test -d /tmp/autopkgtest.H8NDfW/build.DLR/src/; then mkdir --
/tmp/autopkgtest.H8NDfW/build.DLR/src/; fi; cd-
autopkgtest-virt-qemu: DBG: +>?
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2056461
Title:
autopkgtest-virt-qemu on noble images sometimes hangs doing copydown
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/autopkgtest/+bug/2056461/+subscriptions
--
ubuntu-bugs mailing list
ubuntu-bugs@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
