Hang in fsync02 LTP test

[arthurp]

There is a very very common (though maybe not totally deterministic) hang when running the LTP fsync02 test.

Some logs of the error are here: https://gist.github.com/arthurp/8b53a7de0321076cbf3fad5b1714ef62. Note that the sh: systemd-detect-virt: not found error appears in the successful run as well, so it may be unrelated.

This problem only appears when testing on ext2 (in the /ext2 mount point).

Reproduction

make run AUTO_TEST=syscall RELEASE=1 SYSCALL_TEST_SUITE=ltp SYSCALL_TEST_WORKDIR=/ext2

This was run at b2883df (though it also happens on at least 9b746f0) on @arthurp's laptop:

$ lsb_release -a
...
Description:    Pop!_OS 24.04 LTS
...
$ uname -a
Linux hooks 6.18.7-76061807-generic #202601231045~1769703228~24.04~cb87b5b SMP PREEMPT_DYNAMIC Thu J x86_64 x86_64 x86_64 GNU/Linux

[arthurp]

This is not consistently failing in CI: https://github.com/ldos-project/asterinas/actions/runs/22418880095/job/64911569582?pr=172#step:4:4785.

Details

``` <<>> tag=fsync02 stime=1772059170 cmdline="fsync02 " contacts="" analysis=exit <<>> tst_tmpdir.c:316: TINFO: Using /ext2/ltp-XXXXtUMeSA/LTP_fsyFgLUIW as tmpdir (ext2/ext3/ext4 filesystem) tst_memutils.c:152: TINFO: oom_score_adj does not exist, skipping the adjustment tst_test.c:1898: TINFO: LTP version: 20250130-1-gfe8938186 tst_test.c:1902: TINFO: Tested kernel: 5.13.0 5.13.0 x86_64 tst_kconfig.c:71: TINFO: Couldn't locate kernel config! tst_test.c:1720: TINFO: Overall timeout per run is 0h 05m 30s tst_memutils.c:152: TINFO: oom_score_adj does not exist, skipping the adjustment sh: systemd-detect-virt: not found fsync02.c:103: TPASS: fsync succeeded in an acceptable amount of time

Summary:
passed 1
failed 0
broken 0
skipped 0
warnings 0
<<<execution_status>>>
initiation_status="ok"
duration=0 termination_type=exited termination_id=0 corefile=no
cutime=2111926777 cstime=344
<<<test_end>>>

</details>

[ioeddk]

I can reproduce this as well. Hanging happens when using SYSCALL_TEST_WORKDIR=/ext2. But running tests under / doesn't seem to hang.