Re: [syzbot] possible deadlock in throtl_pending_timer_fn

[syzbot]

syzbot has bisected this issue to:

commit 0a9a25ca78437b39e691bcc3dc8240455b803d8d
Author: Ming Lei <ming.lei@xxxxxxxxxx>
Date:   Fri Mar 18 13:01:43 2022 +0000

    block: let blkcg_gq grab request queue's refcnt

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16c3cfc2080000
start commit:   cb71b93c2dc3 Add linux-next specific files for 20220628
git tree:       linux-next
final oops:     https://syzkaller.appspot.com/x/report.txt?x=15c3cfc2080000
console output: https://syzkaller.appspot.com/x/log.txt?x=11c3cfc2080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=badbc1adb2d582eb
dashboard link: https://syzkaller.appspot.com/bug?extid=934ebb67352c8a490bf3
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17713dee080000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15d24952080000

Reported-by: syzbot+934ebb67352c8a490bf3@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 0a9a25ca7843 ("block: let blkcg_gq grab request queue's refcnt")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection