On Fri, Jan 8, 2021 at 6:30 AM Al Viro <v...@zeniv.linux.org.uk> wrote: > > On Tue, Jan 05, 2021 at 11:29:11AM -0700, Jens Axboe wrote: > > Song reported a boot regression in a kvm image with 5.11-rc, and bisected > > it down to the below patch. Debugging this issue, turns out that the boot > > stalled when a task is waiting on a pipe being released. As we no longer > > run task_work from get_signal() unless it's queued with TWA_SIGNAL, the > > task goes idle without running the task_work. This prevents ->release() > > from being called on the pipe, which another boot task is waiting on. > > > > Use TWA_SIGNAL for the file fput work to ensure it's run before the task > > goes idle. > > > > Fixes: 98b89b649fce ("signal: kill JOBCTL_TASK_WORK") > > Reported-by: Song Liu <songliubrav...@fb.com> > > Signed-off-by: Jens Axboe <ax...@kernel.dk> > > > > --- > > > > The other alternative here is obviously to re-instate the: > > > > if (unlikely(current->task_works)) > > task_work_run(); > > > > in get_signal() that we had before this change. Might be safer in case > > there are other cases that need to ensure the work is run in a timely > > fashion, though I do think it's cleaner to long term to correctly mark > > task_work with the needed notification type. Comments welcome... > > Interesting... I think I've missed the discussion of that thing; could > you forward the relevant thread my way or give an archive link to it?
See [1]. - Sedat - [1] https://marc.info/?t=160987156600001&r=1&w=2