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Message-ID: <541f398a-1ac2-3cc8-33cc-eda9511c7e2e@gmail.com>
Date:   Thu, 12 Jan 2023 10:37:44 +0000
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Subject: Re: [syzbot] WARNING: ODEBUG bug in __io_put_task
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To:     syzbot <syzbot+1aa0bce76589e2e98756@syzkaller.appspotmail.com>,
        axboe@kernel.dk, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
References: <00000000000098a61b05f20e62db@google.com>
From:   Pavel Begunkov <asml.silence@gmail.com>
In-Reply-To: <00000000000098a61b05f20e62db@google.com>
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On 1/12/23 10:14, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    0a093b2893c7 Add linux-next specific files for 20230112
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=14d269ce480000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=835f3591019836d5
> dashboard link: https://syzkaller.appspot.com/bug?extid=1aa0bce76589e2e98756
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> 
> Unfortunately, I don't have any reproducer for this issue yet.

#syz test: git://git.kernel.dk/linux.git syztest

> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/8111a570d6cb/disk-0a093b28.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/ecc135b7fc9a/vmlinux-0a093b28.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/ca8d73b446ea/bzImage-0a093b28.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+1aa0bce76589e2e98756@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> ODEBUG: free active (active state 1) object: ffff88801fe06ca8 object type: rcu_head hint: 0x0
> WARNING: CPU: 0 PID: 6765 at lib/debugobjects.c:509 debug_print_object+0x194/0x2c0 lib/debugobjects.c:509
> Modules linked in:
> CPU: 0 PID: 6765 Comm: kworker/0:29 Not tainted 6.2.0-rc3-next-20230112-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
> Workqueue: events io_fallback_req_func
> RIP: 0010:debug_print_object+0x194/0x2c0 lib/debugobjects.c:509
> Code: df 48 89 fe 48 c1 ee 03 80 3c 16 00 0f 85 c7 00 00 00 48 8b 14 dd c0 dc a6 8a 50 4c 89 ee 48 c7 c7 80 d0 a6 8a e8 00 79 ae 05 <0f> 0b 58 83 05 ce 27 66 0a 01 48 83 c4 20 5b 5d 41 5c 41 5d 41 5e
> RSP: 0018:ffffc900057df950 EFLAGS: 00010286
> RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
> RDX: ffff88807d03d7c0 RSI: ffffffff8166972c RDI: fffff52000afbf1c
> RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8a4dd0a0
> R13: ffffffff8aa6d580 R14: ffff88802a8da408 R15: 0000000000000000
> FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055574b30e000 CR3: 000000001ddab000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   <TASK>
>   __debug_check_no_obj_freed lib/debugobjects.c:996 [inline]
>   debug_check_no_obj_freed+0x305/0x420 lib/debugobjects.c:1027
>   slab_free_hook mm/slub.c:1756 [inline]
>   slab_free_freelist_hook+0xeb/0x1c0 mm/slub.c:1807
>   slab_free mm/slub.c:3787 [inline]
>   kmem_cache_free+0xec/0x4e0 mm/slub.c:3809
>   put_task_struct_many include/linux/sched/task.h:125 [inline]
>   __io_put_task+0x155/0x1e0 io_uring/io_uring.c:725
>   io_put_task io_uring/io_uring.h:328 [inline]
>   __io_req_complete_post+0x7ac/0xcd0 io_uring/io_uring.c:978
>   io_req_complete_post+0xf1/0x1a0 io_uring/io_uring.c:992
>   io_req_task_complete+0x189/0x260 io_uring/io_uring.c:1623
>   io_poll_task_func+0xa95/0x1220 io_uring/poll.c:347
>   io_fallback_req_func+0xfd/0x204 io_uring/io_uring.c:252
>   process_one_work+0x9bf/0x1750 kernel/workqueue.c:2293
>   worker_thread+0x669/0x1090 kernel/workqueue.c:2440
>   kthread+0x2e8/0x3a0 kernel/kthread.c:376
>   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>   </TASK>
> 
> 
> ---
> 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@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

-- 
Pavel Begunkov