bisecting fixing commit since 4fa640dc52302b5e62b01b05c755b055549633ae
building syzkaller on d88894e6773ab63ac8b3f4b2edbae88290aaf0d6
testing commit 4fa640dc52302b5e62b01b05c755b055549633ae with gcc (GCC) 8.1.0
kernel signature: f830c03ccccdc4957dd026eefcd7458446be7c8c7ea7f0159f098ebd98b9d7a9
run #0: crashed: INFO: rcu detected stall in mutex_spin_on_owner
run #1: crashed: INFO: rcu detected stall in corrupted
run #2: crashed: INFO: rcu detected stall in mutex_spin_on_owner
run #3: crashed: INFO: rcu detected stall in do_idle
run #4: crashed: INFO: rcu detected stall in do_idle
run #5: crashed: INFO: rcu detected stall in smp_call_function
run #6: crashed: INFO: rcu detected stall in do_idle
run #7: crashed: INFO: rcu detected stall in do_idle
run #8: crashed: INFO: rcu detected stall in do_idle
run #9: crashed: BUG: soft lockup in do_idle
testing current HEAD 7eac66d0456fe12a462e5c14c68e97c7460989da
testing commit 7eac66d0456fe12a462e5c14c68e97c7460989da with gcc (GCC) 8.1.0
kernel signature: e9739837c708e9f14146af800dec612ec36ab798ad1f0db485cdd307cd1d2e05
run #0: crashed: INFO: rcu detected stall in corrupted
run #1: crashed: INFO: rcu detected stall in mutex_spin_on_owner
run #2: crashed: INFO: rcu detected stall in do_idle
run #3: crashed: INFO: rcu detected stall in corrupted
run #4: crashed: INFO: rcu detected stall in corrupted
run #5: crashed: INFO: rcu detected stall in do_idle
run #6: crashed: INFO: rcu detected stall in do_idle
run #7: crashed: INFO: rcu detected stall in do_idle
run #8: crashed: INFO: rcu detected stall in do_idle
run #9: crashed: INFO: task hung in switchdev_deferred_process_work
revisions tested: 2, total time: 25m1.901892709s (build: 9m11.072721404s, test: 15m17.54268414s)
the crash still happens on HEAD
commit msg: Merge tag 'vfio-v5.9-rc2' of git://github.com/awilliam/linux-vfio
crash: INFO: task hung in switchdev_deferred_process_work
INFO: task kworker/1:0:17 blocked for more than 141 seconds.
      Not tainted 5.9.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:0     state:D stack:14136 pid:   17 ppid:     2 flags:0x00004000
Workqueue: events switchdev_deferred_process_work
Call Trace:
 context_switch kernel/sched/core.c:3778 [inline]
 __schedule+0x3f3/0x880 kernel/sched/core.c:4527
 schedule+0x37/0xe0 kernel/sched/core.c:4602
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4661
 __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
 __mutex_lock+0x472/0x9f0 kernel/locking/mutex.c:1103
 switchdev_deferred_process_work+0x5/0x10 net/switchdev/switchdev.c:74
 process_one_work+0x26a/0x5f0 kernel/workqueue.c:2269
 worker_thread+0x38/0x380 kernel/workqueue.c:2415