On 15/03/2021 11:58, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 75013c6c Merge tag 'perf_urgent_for_v5.12-rc3' of git://gi.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=174df32ad00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=844457676c06b88c > dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d > userspace arch: i386 > > 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+d6218cb2fae0b2411e9d@xxxxxxxxxxxxxxxxxxxxxxxxx > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 53 at lib/percpu-refcount.c:113 __percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113 if (percpu_count) { /* non-NULL confirm_switch indicates switching in progress */ WARN_ON_ONCE(ref->data && ref->data->confirm_switch); ... } Points to this warning. Not sure, but not yet included "io_uring: halt SQO submission on ctx exit" may fix it or at least is related. > Modules linked in: > CPU: 1 PID: 53 Comm: kworker/u4:2 Not tainted 5.12.0-rc2-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: events_unbound io_ring_exit_work > RIP: 0010:__percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113 > Code: fd 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 61 49 83 7c 24 10 00 74 07 e8 28 42 ac fd <0f> 0b e8 21 42 ac fd 48 89 ef e8 e9 fa da fd 48 89 da 48 b8 00 00 > RSP: 0018:ffffc90000f1fb78 EFLAGS: 00010293 > RAX: 0000000000000000 RBX: ffff88805c976000 RCX: 0000000000000000 > RDX: ffff888011839bc0 RSI: ffffffff83c76be8 RDI: ffff88802b2a9010 > RBP: 0000607f46077778 R08: 0000000000000000 R09: ffffffff8fab0967 > R10: ffffffff83c76b88 R11: 0000000000000009 R12: ffff88802b2a9000 > R13: 0000000000000001 R14: ffff88802b2a9000 R15: dffffc0000000000 > FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000085a0004 CR3: 000000001896a000 CR4: 00000000001506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > percpu_ref_exit+0x3b/0x140 lib/percpu-refcount.c:134 > io_ring_ctx_free fs/io_uring.c:8419 [inline] > io_ring_exit_work+0x599/0xcf0 fs/io_uring.c:8565 > process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 > kthread+0x3b1/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > -- Pavel Begunkov
