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Subject: Re: linux-next boot error: kernel panic: VFS: Unable to mount root fs
 on unknown-block(0,0)
To:     Dmitry Vyukov <dvyukov@google.com>,
        syzbot <syzbot+b22ad1a79afb8da726c5@syzkaller.appspotmail.com>
Cc:     Jens Axboe <axboe@kernel.dk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Hannes Reinecke <hare@suse.de>, Jan Kara <jack@suse.cz>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux-Next Mailing List <linux-next@vger.kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Tejun Heo <tj@kernel.org>
References: <0000000000003be5f605bad34c09@google.com>
 <CACT4Y+Y4rfBqsoF4DDPYoyrZYFzGNO+hNKcu1QkFNcec2VY8xQ@mail.gmail.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <c49478fd-f5a1-f234-0b70-c6f61b155ab0@infradead.org>
Date:   Mon, 8 Feb 2021 16:05:11 -0800
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On 2/8/21 6:28 AM, Dmitry Vyukov wrote:
> On Mon, Feb 8, 2021 at 2:39 PM syzbot
> <syzbot+b22ad1a79afb8da726c5@syzkaller.appspotmail.com> wrote:
>>
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    8d374d0d Add linux-next specific files for 20210208
>> git tree:       linux-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=13de8a40d00000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=ced6adcf6aff98d6
>> dashboard link: https://syzkaller.appspot.com/bug?extid=b22ad1a79afb8da726c5
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+b22ad1a79afb8da726c5@syzkaller.appspotmail.com
>>
>> netconsole: network logging started
>> gtp: GTP module loaded (pdp ctx size 104 bytes)
>> rdma_rxe: loaded
>> cfg80211: Loading compiled-in X.509 certificates for regulatory database
>> cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
>> ALSA device list:
>>   #0: Dummy 1
>>   #1: Loopback 1
>>   #2: Virtual MIDI Card 1
>> md: Waiting for all devices to be available before autodetect
>> md: If you don't use raid, use raid=noautodetect
>> md: Autodetecting RAID arrays.
>> md: autorun ...
>> md: ... autorun DONE.
>> VFS: Cannot open root device "sda1" or unknown-block(0,0): error -6
> 
> Has anything changed in linux-next related to block devices?... It was
> supposed to boot from a standard GCE VM disk, but it does not seem to
> be probed by the kernel (should be /dev/sda).

Hi Dmitry,

This isn't going to help you much, but next-20210208 boots fine for me
using SATA w/ AHCI and EXT4FS on my test laptop.


>> Please append a correct "root=" boot option; here are the available partitions:
>> 0100            4096 ram0
>>  (driver?)
>> 0101            4096 ram1
>>  (driver?)
>> 0102            4096 ram2
>>  (driver?)
>> 0103            4096 ram3
>>  (driver?)
>> 0104            4096 ram4
>>  (driver?)
>> 0105            4096 ram5
>>  (driver?)
>> 0106            4096 ram6
>>  (driver?)
>> 0107            4096 ram7
>>  (driver?)
>> 0108            4096 ram8
>>  (driver?)
>> 0109            4096 ram9
>>  (driver?)
>> 010a            4096 ram10
>>  (driver?)
>> 010b            4096 ram11
>>  (driver?)
>> 010c            4096 ram12
>>  (driver?)
>> 010d            4096 ram13
>>  (driver?)
>> 010e            4096 ram14
>>  (driver?)
>> 010f            4096 ram15
>>  (driver?)
>> 1f00             128 mtdblock0
>>  (driver?)
>> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
>> CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.11.0-rc6-next-20210208-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> Call Trace:
>>  __dump_stack lib/dump_stack.c:79 [inline]
>>  dump_stack+0x107/0x163 lib/dump_stack.c:120
>>  panic+0x306/0x73d kernel/panic.c:231
>>  mount_block_root+0x3f8/0x4dd init/do_mounts.c:445
>>  mount_root+0x1af/0x1f5 init/do_mounts.c:561
>>  prepare_namespace+0x1ff/0x234 init/do_mounts.c:613
>>  kernel_init_freeable+0x671/0x689 init/main.c:1550
>>  kernel_init+0xd/0x1b8 init/main.c:1426
>>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
>> Kernel Offset: disabled
>> Rebooting in 86400 seconds..
>>
>>
>> ---
>> 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.


-- 
~Randy