Re: INFO: rcu detected stall in __perf_sw_event

[syzbot]

syzbot has bisected this bug to:

commit cf85d89562f39cc7ae73de54639f1915a9195b7a
Author: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
Date:   Fri May 25 07:34:36 2018 +0000

    m68k/mac: Enable PDMA for PowerBook 500 series

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1226cb8b200000
start commit:   b0314565 Merge tag 'for_linus' of git://git.kernel.org/pub..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1126cb8b200000
console output: https://syzkaller.appspot.com/x/log.txt?x=1626cb8b200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8f00801d7b7c4fe6
dashboard link: https://syzkaller.appspot.com/bug?extid=a41ac89a0712acde0e84
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1707cd2f400000

Reported-by: syzbot+a41ac89a0712acde0e84@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: cf85d89562f3 ("m68k/mac: Enable PDMA for PowerBook 500 series")

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