On Sun, Jan 16, 2022 at 04:05:24PM -0800, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 79e06c4c4950 Merge tag 'for-linus' of git://git.kernel.org.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1285ed28700000 > kernel config: https://syzkaller.appspot.com/x/.config?x=afd3ce8cd5cf174b > dashboard link: https://syzkaller.appspot.com/bug?extid=985a662ba46639a7897f > compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+985a662ba46639a7897f@xxxxxxxxxxxxxxxxxxxxxxxxx > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 3640 at kernel/sched/wait.c:245 __wake_up_pollfree+0x1c7/0x1d0 kernel/sched/wait.c:246 > Modules linked in: > CPU: 0 PID: 3640 Comm: syz-executor.3 Not tainted 5.16.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:__wake_up_pollfree+0x1c7/0x1d0 kernel/sched/wait.c:245 > Code: 0d 00 00 c6 44 08 0f 00 65 48 8b 04 25 28 00 00 00 48 3b 84 24 a0 00 00 00 75 13 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b eb a7 e8 60 3e b0 08 55 41 57 41 56 41 55 41 54 53 48 83 ec > RSP: 0018:ffffc900028cf760 EFLAGS: 00010097 > RAX: ffff88801ec1b130 RBX: 0000000000000046 RCX: dffffc0000000000 > RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000001 > RBP: ffffc900028cf848 R08: dffffc0000000000 R09: ffffed100850025a > R10: ffffed100850025a R11: 0000000000000000 R12: 0000000000000000 > R13: ffffc900028cf7a0 R14: 1ffff92000519ef4 R15: ffff888042801308 > FS: 0000555556549400(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fed83b131b8 CR3: 000000004a82a000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 000000000000802e DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > __cleanup_sighand+0x48/0xa0 kernel/fork.c:1590 > __exit_signal kernel/exit.c:159 [inline] > release_task+0x115f/0x15d0 kernel/exit.c:200 > wait_task_zombie kernel/exit.c:1114 [inline] > wait_consider_task+0x1995/0x2fb0 kernel/exit.c:1341 > do_wait_thread kernel/exit.c:1404 [inline] > do_wait+0x291/0x9d0 kernel/exit.c:1521 > kernel_wait4+0x2a3/0x3c0 kernel/exit.c:1684 > __do_sys_wait4 kernel/exit.c:1712 [inline] > __se_sys_wait4 kernel/exit.c:1708 [inline] > __x64_sys_wait4+0x130/0x1e0 kernel/exit.c:1708 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x7f2aff29e487 > Code: 89 7c 24 10 48 89 4c 24 18 e8 35 50 02 00 4c 8b 54 24 18 8b 54 24 14 41 89 c0 48 8b 74 24 08 8b 7c 24 10 b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 89 44 24 10 e8 65 50 02 00 8b 44 > RSP: 002b:00007ffeabee34f0 EFLAGS: 00000293 ORIG_RAX: 000000000000003d > RAX: ffffffffffffffda RBX: 0000000000000932 RCX: 00007f2aff29e487 > RDX: 0000000040000001 RSI: 00007ffeabee357c RDI: 00000000ffffffff > RBP: 00007ffeabee357c R08: 0000000000000000 R09: 0000000000000010 > R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000032 > R13: 00000000000af2e3 R14: 0000000000000009 R15: 00007ffeabee35e0 > </TASK> > > This is probably caused by io_uring not handling POLLFREE notifications, i.e. this is probably a duplicate of the previous syzbot report https://lore.kernel.org/lkml/000000000000c9a3fb05d4d787a3@xxxxxxxxxx/T/#u ("WARNING in signalfd_cleanup"). It's impossible to be certain without a reproducer, but based on the console output here, some of the programs that syzkaller executed use io_uring. So it's at least plausible. - Eric
