On Wed, Sep 03, 2025 at 07:47:18AM -0700, Linus Torvalds wrote: > On Tue, 2 Sept 2025 at 21:54, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > > > If nobody objects, this goes into #for-next. > > Looks all sane to me. > > What was the issue with generic/475? I have missed that context.. At some point testing that branch has caught a failure in generic/475. Unfortunately, it wouldn't trigger on every run, so there was a possibility that it started earlier. When I went digging, I've found it with trixie kernel (6.12.38 in that kvm, at the time) rebuilt with my local config; the one used by debian didn't trigger that. Bisection by config converged to PREEMPT_VOLUNTARY (no visible failures) changed to PREEMPT (failures happen with odds a bit below 10%). There are several failure modes; the most common is something like ... echo '1' 2>&1 > /sys/fs/xfs/dm-0/error/fail_at_unmount echo '0' 2>&1 > /sys/fs/xfs/dm-0/error/metadata/EIO/max_retries echo '0' 2>&1 > /sys/fs/xfs/dm-0/error/metadata/EIO/retry_timeout_seconds fsstress: check_cwd stat64() returned -1 with errno: 5 (Input/output error) fsstress: check_cwd failure fsstress: check_cwd stat64() returned -1 with errno: 5 (Input/output error) fsstress: check_cwd failure fsstress: check_cwd stat64() returned -1 with errno: 5 (Input/output error) fsstress: check_cwd failure fsstress: check_cwd stat64() returned -1 with errno: 5 (Input/output error) fsstress: check_cwd failure fsstress killed (pid 10824) fsstress killed (pid 10826) fsstress killed (pid 10827) fsstress killed (pid 10828) fsstress killed (pid 10829) umount: /home/scratch: target is busy. unmount failed umount: /home/scratch: target is busy. umount: /dev/sdb2: not mounted. in the end of output (that's mainline v6.12); other variants include e.g. quietly hanging udevadm wait (killable). It's bloody annoying to bisect - 100-iterations run takes about 2.5 hours and while usually a failure happens in the first 40 minutes or so or not at all... PREEMPT definitely is the main contributor to the failure odds... I'm doing a bisection between v6.12 and v6.10 at the moment, will post when I get something more useful...
