Re: INFO: rcu detected stall in ext4_file_write_iter

[syzbot]

Bisection is inconclusive: the bug happens on the oldest tested release.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17b1becf200000
start commit:   [unknown
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1471becf200000
console output: https://syzkaller.appspot.com/x/log.txt?x=1071becf200000
dashboard link: https://syzkaller.appspot.com/bug?extid=7d19c5fe6a3f1161abb7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=103908f8c00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=105e5cd0c00000

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