Re: [syzbot] INFO: task hung in io_sq_thread_park (2)

[Pavel Begunkov]

On 7/16/21 1:14 AM, syzbot wrote:
> Hello,
> 
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> WARNING in io_uring_cancel_generic

attempt to get stats #2

#syz test: https://github.com/isilence/linux.git syztest_sqpoll_hang 

> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 25279 at fs/io_uring.c:9122 io_dump fs/io_uring.c:9117 [inline]
> WARNING: CPU: 1 PID: 25279 at fs/io_uring.c:9122 io_uring_cancel_generic+0x5fb/0xe50 fs/io_uring.c:9195
> Modules linked in:
> CPU: 1 PID: 25279 Comm: iou-sqp-25271 Tainted: G        W         5.14.0-rc1-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:io_dump fs/io_uring.c:9122 [inline]
> RIP: 0010:io_uring_cancel_generic+0x5fb/0xe50 fs/io_uring.c:9195
> Code: 08 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 9e 06 00 00 48 8b 85 10 08 00 00 48 89 44 24 40 <0f> 0b 48 8b 44 24 10 48 05 98 00 00 00 48 89 c2 48 89 44 24 08 48
> RSP: 0018:ffffc9000ab87c50 EFLAGS: 00010246
> RAX: ffff88803ddb7800 RBX: ffff888049f73880 RCX: 0000000000000000
> RDX: 1ffff110093ee812 RSI: ffffffff81e2ebed RDI: ffff888049f74090
> RBP: ffff888049f73880 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffffff81e2ebc5 R11: 0000000000000001 R12: ffffc9000ab87d40
> R13: ffff88803ddb7858 R14: 0000000000000001 R15: 0000000000000000
> FS:  00007fb893f40700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f68dd0c6080 CR3: 000000002b457000 CR4: 0000000000350ef0
> Call Trace:
>  io_sq_thread+0xaac/0x1250 fs/io_uring.c:6930
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 1 PID: 25279 Comm: iou-sqp-25271 Tainted: G        W         5.14.0-rc1-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
>  panic+0x306/0x73d kernel/panic.c:232
>  __warn.cold+0x35/0x44 kernel/panic.c:606
>  report_bug+0x1bd/0x210 lib/bug.c:199
>  handle_bug+0x3c/0x60 arch/x86/kernel/traps.c:239
>  exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:259
>  asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:566
> RIP: 0010:io_dump fs/io_uring.c:9122 [inline]
> RIP: 0010:io_uring_cancel_generic+0x5fb/0xe50 fs/io_uring.c:9195
> Code: 08 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 9e 06 00 00 48 8b 85 10 08 00 00 48 89 44 24 40 <0f> 0b 48 8b 44 24 10 48 05 98 00 00 00 48 89 c2 48 89 44 24 08 48
> RSP: 0018:ffffc9000ab87c50 EFLAGS: 00010246
> RAX: ffff88803ddb7800 RBX: ffff888049f73880 RCX: 0000000000000000
> RDX: 1ffff110093ee812 RSI: ffffffff81e2ebed RDI: ffff888049f74090
> RBP: ffff888049f73880 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffffff81e2ebc5 R11: 0000000000000001 R12: ffffc9000ab87d40
> R13: ffff88803ddb7858 R14: 0000000000000001 R15: 0000000000000000
>  io_sq_thread+0xaac/0x1250 fs/io_uring.c:6930
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
> 
> 
> Tested on:
> 
> commit:         d55b8f3c io_uring: add syz debug info
> git tree:       https://github.com/isilence/linux.git syztest_sqpoll_hang
> console output: https://syzkaller.appspot.com/x/log.txt?x=16f6cb80300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cfe2c0e42bc9993d
> dashboard link: https://syzkaller.appspot.com/bug?extid=ac957324022b7132accf
> compiler:       
> 

-- 
Pavel Begunkov