Re: WARNING in blk_mq_sched_free_requests

[Ming Lei]

Hello,

Thanks for your report!

On Mon, Jun 10, 2019 at 09:05:07PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    d1fdb6d8 Linux 5.2-rc4
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=105ade6aa00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=fa9f7e1b6a8bb586
> dashboard link: https://syzkaller.appspot.com/bug?extid=b9d0d56867048c7bcfde
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11c67dd2a00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=154be66aa00000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+b9d0d56867048c7bcfde@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> Code: e8 bc b5 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 2b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f735bcf2d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 00000000004466e9
> RDX: 0000000000000000 RSI: 0000000000004c80 RDI: 0000000000000003
> RBP: 00000000006dbc30 R08: 0000000000000002 R09: 0000000000003034
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c
> R13: 00007f735bcf2d90 R14: 0000000000000004 R15: 20c49ba5e353f7cf
> WARNING: CPU: 0 PID: 9739 at block/blk-mq-sched.c:558
> blk_mq_sched_free_requests+0x207/0x290 block/blk-mq-sched.c:558
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 9739 Comm: syz-executor118 Not tainted 5.2.0-rc4 #25
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x172/0x1f0 lib/dump_stack.c:113
>  panic+0x2cb/0x744 kernel/panic.c:219
>  __warn.cold+0x20/0x4d kernel/panic.c:576
>  report_bug+0x263/0x2b0 lib/bug.c:186
>  fixup_bug arch/x86/kernel/traps.c:179 [inline]
>  fixup_bug arch/x86/kernel/traps.c:174 [inline]
>  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
>  do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
>  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:986
> RIP: 0010:blk_mq_sched_free_requests+0x207/0x290 block/blk-mq-sched.c:558
> Code: ff e8 6d bf 30 fe 31 ff 89 c3 89 c6 e8 32 ac 4a fe 85 db 0f 85 68 fe
> ff ff e8 a5 aa 4a fe 0f 0b e9 5c fe ff ff e8 99 aa 4a fe <0f> 0b e9 7f fe ff
> ff 48 c7 c7 b4 e5 80 89 e8 b6 48 83 fe e9 28 fe
> RSP: 0018:ffff88808ab9fa60 EFLAGS: 00010293
> RAX: ffff88808c9f6340 RBX: 0000000000000001 RCX: ffffffff8326000e
> RDX: 0000000000000000 RSI: ffffffff83260027 RDI: ffff88809f27b020
> RBP: ffff88808ab9fab0 R08: ffff88808c9f6340 R09: ffffed1015d06be0
> R10: ffffed1015d06bdf R11: ffff8880ae835efb R12: 00000000fffffff4
> R13: ffff88809f27b008 R14: ffff88809ec4e658 R15: ffff88809f27b008
>  blk_mq_init_sched+0x32c/0x770 block/blk-mq-sched.c:542
>  elevator_init_mq+0xcd/0x160 block/elevator.c:622
>  blk_mq_init_allocated_queue+0x10e2/0x15b0 block/blk-mq.c:2921
>  blk_mq_init_queue+0x62/0xb0 block/blk-mq.c:2705
>  loop_add+0x2dd/0x8d0 drivers/block/loop.c:2004
>  loop_control_ioctl drivers/block/loop.c:2157 [inline]
>  loop_control_ioctl+0x165/0x360 drivers/block/loop.c:2139
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:509 [inline]
>  do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696
>  ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
>  __do_sys_ioctl fs/ioctl.c:720 [inline]
>  __se_sys_ioctl fs/ioctl.c:718 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
>  do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x4466e9
> Code: e8 bc b5 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 2b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f735bcf2d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 00000000004466e9
> RDX: 0000000000000000 RSI: 0000000000004c80 RDI: 0000000000000003
> RBP: 00000000006dbc30 R08: 0000000000000002 R09: 0000000000003034
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c
> R13: 00007f735bcf2d90 R14: 0000000000000004 R15: 20c49ba5e353f7cf
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
> 

Patch has been posted out:

https://lore.kernel.org/linux-block/20190611093153.7147-1-ming.lei@xxxxxxxxxx/T/#u

Thanks,
Ming