On Mon, Oct 26, 2020 at 11:26:49AM +0000, Filipe Manana wrote: > Hello, > > I've recently started to hit a warning followed by tasks hanging after > attempts to freeze a filesystem. A git bisection pointed to the > following commit: > > commit 4d004099a668c41522242aa146a38cc4eb59cb1e > Author: Peter Zijlstra <pet...@infradead.org> > Date: Fri Oct 2 11:04:21 2020 +0200 > > lockdep: Fix lockdep recursion > > This happens very reliably when running all xfstests with lockdep > enabled, and the tested filesystem is btrfs (haven't tried other > filesystems, but it shouldn't matter). The warning and task hangs always > happen at either test generic/068 or test generic/390, and (oddly) > always have to run all tests for it to trigger, running those tests > individually on an infinite loop doesn't seem to trigger it (at least > for a couple hours). > > The warning triggered is at fs/super.c:__sb_start_write() which always > results later in several tasks hanging on a percpu rw_sem: > > https://pastebin.com/qnLvf94E > > What happens is percpu_rwsem_is_held() is apparently returning a false > positive,
That smells like the same issue reported here: https://lkml.kernel.org/r/20201022111700.gz2...@hirez.programming.kicks-ass.net Make sure you have commit: f8e48a3dca06 ("lockdep: Fix preemption WARN for spurious IRQ-enable") (in Linus' tree by now) and do you have CONFIG_DEBUG_PREEMPT enabled?
