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Date:   Mon, 17 May 2021 13:28:15 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     syzbot <syzbot+1c24e3484e48799b2333@syzkaller.appspotmail.com>
Cc:     axboe@kernel.dk, hare@suse.de, hch@lst.de,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        martin.petersen@oracle.com, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] WARNING in blk_rq_append_bio
Message-ID: <20210517112815.GA11490@lst.de>
References: <0000000000006d129905c284e02d@google.com>
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This was fixed just a little later with "block: remove an incorrect check from
blk_rq_append_bio"

On Mon, May 17, 2021 at 04:27:20AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    5103a5be Add linux-next specific files for 20210407
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=17b28e36d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c278e8a8a7f47f4c
> dashboard link: https://syzkaller.appspot.com/bug?extid=1c24e3484e48799b2333
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1232b5c9d00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17971a36d00000
> 
> The issue was bisected to:
> 
> commit 393bb12e00580aaa23356504eed38d8f5571153a
> Author: Christoph Hellwig <hch@lst.de>
> Date:   Wed Mar 31 07:30:01 2021 +0000
> 
>     block: stop calling blk_queue_bounce for passthrough requests
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=134e9381d00000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=10ce9381d00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=174e9381d00000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+1c24e3484e48799b2333@syzkaller.appspotmail.com
> Fixes: 393bb12e0058 ("block: stop calling blk_queue_bounce for passthrough requests")
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 25 at block/blk-map.c:488 blk_rq_append_bio+0x565/0x680 block/blk-map.c:488
> Modules linked in:
> CPU: 0 PID: 25 Comm: kworker/u4:1 Not tainted 5.12.0-rc6-next-20210407-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: events_unbound async_run_entry_fn
> RIP: 0010:blk_rq_append_bio+0x565/0x680 block/blk-map.c:488
> Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 de 00 00 00 48 8b 44 24 10 48 89 98 a0 00 00 00 45 31 e4 e9 3f fe ff ff e8 6b 3e bc fd <0f> 0b 41 bc ea ff ff ff e9 2d fe ff ff c7 44 24 08 00 00 00 00 e9
> RSP: 0018:ffffc90000dff6d0 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
> RDX: ffff888011cbb900 RSI: ffffffff83b7ea55 RDI: 0000000000000003
> RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000001
> R10: ffffffff83b7e568 R11: 0000000000000000 R12: 0000000000000001
> R13: 0000000000000008 R14: ffff88801c86e400 R15: ffff88801c86e400
> FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fb8501cc930 CR3: 0000000023c21000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  blk_rq_map_kern+0x5db/0x750 block/blk-map.c:653
>  __scsi_execute+0x4c1/0x600 drivers/scsi/scsi_lib.c:224
>  scsi_execute_req include/scsi/scsi_device.h:462 [inline]
>  read_capacity_10+0x112/0x690 drivers/scsi/sd.c:2442
>  sd_read_capacity drivers/scsi/sd.c:2519 [inline]
>  sd_revalidate_disk.isra.0+0x206c/0x7c00 drivers/scsi/sd.c:3203
>  sd_probe+0x9e5/0x1140 drivers/scsi/sd.c:3459
>  really_probe+0x291/0xf60 drivers/base/dd.c:576
>  driver_probe_device+0x298/0x410 drivers/base/dd.c:763
>  __device_attach_driver+0x203/0x2c0 drivers/base/dd.c:870
>  bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:431
>  __device_attach_async_helper+0x1c9/0x290 drivers/base/dd.c:896
>  async_run_entry_fn+0x9d/0x550 kernel/async.c:127
>  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@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches
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