On 2019/01/19 20:41, Dmitry Vyukov wrote: > On Sat, Jan 19, 2019 at 12:32 PM syzbot > <syzbot+1505c80c74256c611...@syzkaller.appspotmail.com> wrote: >> >> Hello, >> >> syzbot found the following crash on: >> >> HEAD commit: 2339e91d0e66 Merge tag 'media/v5.0-1' of git://git.kernel... >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=175f2638c00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=abc3dc9b7a900258 >> dashboard link: https://syzkaller.appspot.com/bug?extid=1505c80c74256c6118a5 >> compiler: gcc (GCC) 9.0.0 20181231 (experimental) >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12c4dc28c00000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15df4108c00000 > > Looking at the reproducer it looks like something with scheduler as it > involves perf_event_open and sched_setattr. So +Peter and Mingo. > Is it the same root cause as the other stalls involving sched_setattr?
Yes. I think sched_setattr() involves this problem. Reproducers from "BUG: workqueue lockup (4)" at https://syzkaller.appspot.com/text?tag=ReproC&x=13ec31a5400000 involves sched_setattr(SCHED_DEADLINE) and https://syzkaller.appspot.com/text?tag=ReproC&x=104da690c00000 also involves sched_setattr().
