On Sat, Nov 6, 2021 at 6:49 PM Ammar Faizi wrote: > > This is the reproducer for the kworker hang bug. > > Reproduction Steps: > 1) A user task calls io_uring_queue_exit(). > > 2) Suspend the task with SIGSTOP / SIGTRAP before the ring exit is > finished (do it as soon as step (1) is done). > > 3) Wait for `/proc/sys/kernel/hung_task_timeout_secs` seconds > elapsed. > > 4) We get a complaint from the khungtaskd because the kworker is > stuck in an uninterruptible state (D). > > The kworkers waiting on ring exit are not progressing as the task > cannot proceed. When the user task is continued (e.g. get SIGCONT > after SIGSTOP, or continue after SIGTRAP breakpoint), the kworkers > then can finish the ring exit. > > We need a special handling for this case to avoid khungtaskd > complaint. Currently we don't have the fix for this. [...] > Cc: Pavel Begunkov <asml.silence@xxxxxxxxx> > Link: https://github.com/axboe/liburing/issues/448 > Signed-off-by: Ammar Faizi <ammar.faizi@xxxxxxxxxxxxxxxxxxxxx> > --- > > v6: > - Fix missing call to restore_hung_entries() when fork() fails. > > .gitignore | 1 + > test/Makefile | 1 + > test/kworker-hang.c | 323 ++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 325 insertions(+) > create mode 100644 test/kworker-hang.c It's ready for review. -- Ammar Faizi
