On Sat, May 11, 2024 at 07:14:39PM +0200, Mickaël Salaün wrote:
Fix a race condition when running several FIXTURE_TEARDOWN() managing the same resource. This fixes a race condition in the Landlock file system tests when creating or unmounting the same directory.
Using clone3() with CLONE_VFORK guarantees that the child and grandchild test processes are sequentially scheduled. This is implemented with a new clone3_vfork() helper replacing the fork() call.
This is now in mainline and appears to be causing several tests (at least the ptrace vmaccess global_attach test on arm64, possibly also some of the epoll tests) that previously were timed out by the harness to to hang instead. A bisect seems to point at this patch in particular, there was a bunch of discussion of the fallout of these patches but I'm afraid I lost track of it, is there something in flight for this? -next is affected as well from the looks of it.
Log of the ptrace issue (not that it's useful, the job just gets killed by the test runner):
https://lava.sirena.org.uk/scheduler/job/307984
Bisect log:
git bisect start # status: waiting for both good and bad commits # good: [e8f897f4afef0031fe618a8e94127a0934896aba] Linux 6.8 git bisect good e8f897f4afef0031fe618a8e94127a0934896aba # status: waiting for bad commit, 1 good commit known # bad: [a38297e3fb012ddfa7ce0321a7e5a8daeb1872b6] Linux 6.9 git bisect bad a38297e3fb012ddfa7ce0321a7e5a8daeb1872b6 # good: [480e035fc4c714fb5536e64ab9db04fedc89e910] Merge tag 'drm-next-2024-03-13' of https://gitlab.freedesktop.org/drm/kernel git bisect good 480e035fc4c714fb5536e64ab9db04fedc89e910 # good: [2ac2b1665d3fbec6ca709dd6ef3ea05f4a51ee4c] Merge tag 'hwlock-v6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux git bisect good 2ac2b1665d3fbec6ca709dd6ef3ea05f4a51ee4c # good: [e858beeddfa3a400844c0e22d2118b3b52f1ea5e] bcachefs: If we run merges at a lower watermark, they must be nonblocking git bisect good e858beeddfa3a400844c0e22d2118b3b52f1ea5e # good: [e43afae4a335ac0bf54c7a8f23ed65dd55449649] Merge tag 'powerpc-6.9-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux git bisect good e43afae4a335ac0bf54c7a8f23ed65dd55449649 # good: [09e10499ee6a5a89fc352f25881276398a49596a] Merge tag 'drm-misc-fixes-2024-05-02' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-fixes git bisect good 09e10499ee6a5a89fc352f25881276398a49596a # good: [3c15237018eb8a9a56bb49a5dbf4d8eeb154b5cc] Merge tag 'usb-6.9-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb git bisect good 3c15237018eb8a9a56bb49a5dbf4d8eeb154b5cc # good: [62788b0f225da1837ad38101112e2c49123470ee] Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux git bisect good 62788b0f225da1837ad38101112e2c49123470ee # good: [ed44935c330a2633440e8d2660db3c7538eeaf10] Merge tag 'spi-fix-v6.9-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi git bisect good ed44935c330a2633440e8d2660db3c7538eeaf10 # good: [c22c3e0753807feee1391a22228b0d5e6ba39b74] Merge tag 'mm-hotfixes-stable-2024-05-10-13-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm git bisect good c22c3e0753807feee1391a22228b0d5e6ba39b74 # good: [b61821bb32c5577272408e1b05e6a0879a64257f] Merge tag 'drm-misc-fixes-2024-05-10' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-fixes git bisect good b61821bb32c5577272408e1b05e6a0879a64257f # bad: [323feb3bdb67649bfa5614eb24ec9cb92a60cf33] selftests/harness: Handle TEST_F()'s explicit exit codes git bisect bad 323feb3bdb67649bfa5614eb24ec9cb92a60cf33 # bad: [323feb3bdb67649bfa5614eb24ec9cb92a60cf33] selftests/harness: Handle TEST_F()'s explicit exit codes git bisect bad 323feb3bdb67649bfa5614eb24ec9cb92a60cf33 # bad: [3656bc23429a4d539c81b5cb8f17ceeeeca8901a] selftests/landlock: Do not allocate memory in fixture data git bisect bad 3656bc23429a4d539c81b5cb8f17ceeeeca8901a # good: [7e4042abe2ee7c0977fd8bb049a6991b174a5e6f] selftests/landlock: Fix FS tests when run on a private mount point git bisect good 7e4042abe2ee7c0977fd8bb049a6991b174a5e6f # bad: [a86f18903db9211e265cc130b61adb175b7a4c42] selftests/harness: Fix interleaved scheduling leading to race conditions git bisect bad a86f18903db9211e265cc130b61adb175b7a4c42 # good: [fff37bd32c7605d93bf900c4c318d56d12000048] selftests/harness: Fix fixture teardown git bisect good fff37bd32c7605d93bf900c4c318d56d12000048 # first bad commit: [a86f18903db9211e265cc130b61adb175b7a4c42] selftests/harness: Fix interleaved scheduling leading to race conditions