Re: INFO: rcu detected stall in new_sync_read

[Tetsuo Handa]

On 2020/01/07 5:54, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:ÂÂÂ bed72351 Merge tag 'kbuild-fixes-v5.5-2' of git://git.kern..
> git tree:ÂÂÂÂÂÂ upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1747aec6e00000
> kernel config:Â https://syzkaller.appspot.com/x/.config?x=874bac2ff63646fa
> dashboard link: https://syzkaller.appspot.com/bug?extid=8a95855c8a4649d98244
> compiler:ÂÂÂÂÂÂ gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:ÂÂÂÂÂ https://syzkaller.appspot.com/x/repro.syz?x=11c26859e00000
> C reproducer:ÂÂ https://syzkaller.appspot.com/x/repro.c?x=1307e6b9e00000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+8a95855c8a4649d98244@xxxxxxxxxxxxxxxxxxxxxxxxx
> 

Dmitry, this looks like yet another stall report doing sched_setattr(SCHED_RR)
followed by sendfile()/fallocate() etc...