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(Solved) kernel panic - not syncing: vfs: unable to mount
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FrankRizz0
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PostPosted: Fri Jul 27, 2018 5:35 pm    Post subject: (Solved) kernel panic - not syncing: vfs: unable to mount Reply with quote

Good afternoon all!

So the complete error was
Code:
kernel panic - not syncing: vfs: unable to mount root fs on unknown-block(8,4)


Starting from the beginning, I bought a used server that I wanted for a NAS. Turns out that Open Media Vault / FreeNAS doesn't suit my needs (nor do I like them much) so I decided to change it into a Gentoo box, and turn it into an HTPC. I have no idea what the error means (8,4) so I am not sure where to begin. My fstab is here:

https://paste.pound-python.org/show/zhMT46SMRHb0lmfhwW7S/

My lspci -k located here:

https://paste.pound-python.org/show/s2ekNk0mJA1ZDy0VngeW/

And my kernel config is here:

https://paste.pound-python.org/show/ntWMUViLVcjHkSSt3Qbb/


Last edited by FrankRizz0 on Mon Jul 30, 2018 11:32 am; edited 1 time in total
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axl
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PostPosted: Fri Jul 27, 2018 5:57 pm    Post subject: Reply with quote

My guess is: you didn't include the proper disk support in the kernel. With "old server" is hard to guess what that would be. Could be anything from pata/sata/scsi or any of the raids. My suggestion is boot again the live cd and analyze dmesg/lspci from there, not from your kernel which doesn't include the obvious support you need.
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NeddySeagoon
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PostPosted: Fri Jul 27, 2018 6:19 pm    Post subject: Reply with quote

FrankRizz0,

unknown-block(8,4) tells the kernel major and minor device numbers that the kernel is trying to mount as root.
That's /dev/sda4.

That you get (8,4) tells that the kernel can see something there but not understand what it finds.
Maybe the root filesystem driver is missing from the kernel?
Unless you have an initrd, <M> won't work.

Perhaps the live kernel and install media don't agree on what /dev/sda4 is?
As the box is/was a NAS, it will have several drives.

Grub lets you edit the in memory copy of the boot stanza ... press 'e' and do same trial and error.

Maybe you used a USB stick as install media and its still plugged in?
On some systems USB storage devices are enumerated before HDD?
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FrankRizz0
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PostPosted: Fri Jul 27, 2018 7:21 pm    Post subject: Reply with quote

Thanks for the reply Neddy. I removed the drives from the box besides one additional drive. I did the install using the LiveDVD on a USB stick, and also made sure to change it back to boot from the hard drive. Not exactly sure what you mean by <M>. Also, I'm unsure regarding pressing 'e', are you referring during the boot process to press e?
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PostPosted: Fri Jul 27, 2018 7:26 pm    Post subject: Reply with quote

FrankRizz0 wrote:
Thanks for the reply Neddy. I removed the drives from the box besides one additional drive. I did the install using the LiveDVD on a USB stick, and also made sure to change it back to boot from the hard drive. Not exactly sure what you mean by <M>. Also, I'm unsure regarding pressing 'e', are you referring during the boot process to press e?


the <m> means that you could have had the kernel compiled for some hardware disk controllers as Modules (m stands for module) and in case you do have that, you would need an additional initrd image. you didn't have any M in disk stuff, i checked. but U do have very basic disc support in kernel. and servers usually have specialized disk controllers that include something other then just piix.

again, you are missing stuff from the kernel in either sata/scsi department. compare output from livedvd or whatever media you installed from that is seeing the controller, with dmesg from your own kernel that is lacking support.
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PostPosted: Fri Jul 27, 2018 7:29 pm    Post subject: Reply with quote

a total of 20 =m in the config. no way in hell it is the initrd file. Take a look at sata. Only has piix.

He said it's an old server. Has xeon. Certainly has a server type disk controller instead of piix.
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FrankRizz0
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PostPosted: Fri Jul 27, 2018 7:45 pm    Post subject: Reply with quote

Thanks for your help axl. Below is the output of dmesg:

https://paste.pound-python.org/show/uB4L5XRXa8HzxPsJ5RpL/

and I found some strange inconsistencies:

Code:
[   15.889250] EXT4-fs (sda2): couldn't mount as ext3 due to feature incompatibilities
[   15.889378] EXT4-fs (sda2): mounting ext2 file system using the ext4 subsystem
[   15.910827] EXT4-fs (sda2): mounted filesystem without journal. Opts: (null)
[   15.953557] EXT4-fs (sda4): couldn't mount as ext3 due to feature incompatibilities
[   15.953683] EXT4-fs (sda4): couldn't mount as ext2 due to feature incompatibilities
[   16.020556] EXT4-fs (sda4): mounted filesystem with ordered data mode. Opts: (null)
[   16.063104] EXT4-fs (sdb1): couldn't mount as ext3 due to feature incompatibilities
[   16.063265] EXT4-fs (sdb1): couldn't mount as ext2 due to feature incompatibilities
[   16.122477] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: (null)


When I looked through that, I decided to check out fdisk -l, whic I posted here:

https://paste.pound-python.org/show/RAgYj8dIycNp4ObnB2N0/

What I found very strange is that I only have 2 drives, not three. Even more curious is that someone tried to install an EFI boot on it. The system is definitely bios and not efi, I have checked and double checked. Anyhow, I deleted them.
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NeddySeagoon
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PostPosted: Fri Jul 27, 2018 7:46 pm    Post subject: Reply with quote

FrankRizz0,

When the grub menu appears, choose the option you want but press the 'e' key, not enter.

If you have a part of the SCSI stack missing, the error is usually unknown-block(0,0).
The <M> refers to the kernel menuconfig symbol means that something is to be made available as a loadable module. <*> indicates that the code is to be included in the kernel binary.

It matters because booting is solving the problem of loading an operating system from disk, on a computer that can read exactly one disk block. There are lots of circular dependencies to be broken.
Consider the following. There is a loadable module required to mount the root filesystem. The module is on the root filesystem, therefore it cannot be loaded until root is mounted.
There are two solutions build a kernel that can boot without needing loadable module support, or provide the modules in a temporary root filesystem, which is what an initrd is.

Tell us how you made your kernel.

Put your lspci output into a post.

Using wgetpaste, put your kernel .config file onto a pastebin site and post a link to it.

Tell us which filesystem types you have on which partitions.
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axl
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PostPosted: Fri Jul 27, 2018 7:51 pm    Post subject: Reply with quote

FrankRizz0 wrote:
Thanks for your help axl. Below is the output of dmesg:

https://paste.pound-python.org/show/uB4L5XRXa8HzxPsJ5RpL/

and I found some strange inconsistencies:

Code:
[   15.889250] EXT4-fs (sda2): couldn't mount as ext3 due to feature incompatibilities
[   15.889378] EXT4-fs (sda2): mounting ext2 file system using the ext4 subsystem
[   15.910827] EXT4-fs (sda2): mounted filesystem without journal. Opts: (null)
[   15.953557] EXT4-fs (sda4): couldn't mount as ext3 due to feature incompatibilities
[   15.953683] EXT4-fs (sda4): couldn't mount as ext2 due to feature incompatibilities
[   16.020556] EXT4-fs (sda4): mounted filesystem with ordered data mode. Opts: (null)
[   16.063104] EXT4-fs (sdb1): couldn't mount as ext3 due to feature incompatibilities
[   16.063265] EXT4-fs (sdb1): couldn't mount as ext2 due to feature incompatibilities
[   16.122477] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: (null)


When I looked through that, I decided to check out fdisk -l, whic I posted here:

https://paste.pound-python.org/show/RAgYj8dIycNp4ObnB2N0/

What I found very strange is that I only have 2 drives, not three. Even more curious is that someone tried to install an EFI boot on it. The system is definitely bios and not efi, I have checked and double checked. Anyhow, I deleted them.


Nope, seems to be covered by ahci. Have no clue then...
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axl
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PostPosted: Fri Jul 27, 2018 7:52 pm    Post subject: Reply with quote

NeddySeagoon wrote:
Put your lspci output into a post.

Using wgetpaste, put your kernel .config file onto a pastebin site and post a link to it.


it's in the first post neddy.
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FrankRizz0
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PostPosted: Fri Jul 27, 2018 7:54 pm    Post subject: Reply with quote

My lspci -k located here:

https://paste.pound-python.org/show/s2ekNk0mJA1ZDy0VngeW/

And my kernel config is here:

https://paste.pound-python.org/show/ntWMUViLVcjHkSSt3Qbb/
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FrankRizz0
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PostPosted: Fri Jul 27, 2018 7:58 pm    Post subject: Reply with quote

My fstab is located here:

https://paste.pound-python.org/show/zhMT46SMRHb0lmfhwW7S/

I did find an error with fstab, sdb is actually ext4 not 3, but this wouldn't cause my system not to boot.
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FrankRizz0
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PostPosted: Fri Jul 27, 2018 8:02 pm    Post subject: Reply with quote

Almost forgot, how I built my kernel; I researched what I could from lspci -k output and used google.
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PostPosted: Fri Jul 27, 2018 8:16 pm    Post subject: Reply with quote

I have no clue. Afaik it should have worked. For my own curiosity could you post the output (while on live dvd) of udevadm info -a -n /dev/sda pls ?
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FrankRizz0
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PostPosted: Fri Jul 27, 2018 8:39 pm    Post subject: Reply with quote

https://paste.pound-python.org/show/jrwdeNUwGm04wQAIM1F3/
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PostPosted: Fri Jul 27, 2018 8:43 pm    Post subject: Reply with quote

Thank you. Yes, as expected nothing special. SD disk is on, ext4 is on, ahci is on. Really have no clue.

At this point, If this would happen to me, I would start to wonder if I am booting the kernel I am compiling.

The only question mark I have left based on what you posted is what is on sda1?
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PostPosted: Fri Jul 27, 2018 9:14 pm    Post subject: Reply with quote

U mentioned at one point you tried to treat the system as uefi.

combine that with a vfat first partition on a mbr disc that might include a previous iteration of kernel... and u have prolly your sda1. am I right?

EDIT what I am saying is that the kernel booted from sda1 is not the kernel from /boot on sda2. or kernel compiled on sda4 doesn't get on sda2. either way... that's what i would look at.
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Marlo
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PostPosted: Fri Jul 27, 2018 9:19 pm    Post subject: Reply with quote

FrankRizz0 wrote:
My fstab is located here:

https://paste.pound-python.org/show/zhMT46SMRHb0lmfhwW7S/

I did find an error with fstab, sdb is actually ext4 not 3, but this wouldn't cause my system not to boot.


But did you really create a user named Media?
More specifically: Does the directory /home/Media exist?

Code:
[  220.552406] EXT4-fs (sda4): mounted filesystem with ordered data mode. Opts: (null)
[  236.547968] EXT4-fs (sda2): mounting ext2 file system using the ext4 subsystem
[  236.564880] EXT4-fs (sda2): mounted filesystem without journal. Opts: (null)
[  800.868602]  sdb: sdb1
[  826.413140]  sdb: sdb1

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FrankRizz0
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PostPosted: Fri Jul 27, 2018 9:55 pm    Post subject: Reply with quote

axl you misunderstood, I did not try and build it as a uefi, it was already on the system, so the previous owner tried to install Gentoo and was unsuccessful (I know this because I have researched this system, it is definitely NOT uefi, it is bios). Marlo, sdb would not stop the system from booting. Further to this, yes, I did create a file in /home called Media.

Edit: Sorry, I did not create a user called Media, that is where I mounted sdb.
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PostPosted: Fri Jul 27, 2018 9:58 pm    Post subject: Reply with quote

FrankRizz0 wrote:
axl you misunderstood, I did not try and build it as a uefi, it was already on the system, so the previous owner tried to install Gentoo and was unsuccessful (I know this because I have researched this system, is is definitely NOT uefi, it is bios).


can it be possible that the system boots in a loop from sda1 with a kernel made by the previous user? it would make sense. u're doing boot in sda2.
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FrankRizz0
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PostPosted: Fri Jul 27, 2018 10:00 pm    Post subject: Reply with quote

Possibly, I did not comment sda1 in fstab, maybe that will do the trick (I don't remember ever commenting grub as sda1 in fstab).
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PostPosted: Fri Jul 27, 2018 10:02 pm    Post subject: Reply with quote

FrankRizz0 wrote:
Possibly, I did not comment sda1 in fstab, maybe that will do the trick (I don't remember ever commenting grub as sda1 in fstab).


dude!!! what is on it? start with that. you seem to know what is on 2, 3, 4, but what is on 1? do you know? dont just comment or whatever. figure out what is there.

PS also your last comment made you l33t. congrats on your 600th post. :)
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PostPosted: Fri Jul 27, 2018 10:04 pm    Post subject: Reply with quote

OK so I think I somehow created sda2 as efi:

Code:
/dev/sda1     2048      6143      4096     2M BIOS boot
/dev/sda2     6144    268287    262144   128M EFI System
/dev/sda3   268288   1316863   1048576   512M Linux filesystem
/dev/sda4  1316864 488395119 487078256 232.3G Linux filesystem


This is from fdisk /dev/sda
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PostPosted: Fri Jul 27, 2018 10:08 pm    Post subject: Reply with quote

Like I said in a previous post, I think (bet/gamble 80% sure at this point), the kernel in efi / (slash) boot sda2 is not the kernel you compiled. sda3 is not swap. the whole thing is gpt without a point because is not larger then 2tb. and bios is not uefi.

save everything. make a single partition in mbr or whatever disk layout you like... but certainly not this. and make sure the kernel that has the config you posted is the kernel that is booted, and i'm 80% sure it will work.
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PostPosted: Fri Jul 27, 2018 10:27 pm    Post subject: Reply with quote

i mean, for a bios/mbr setup, your partition layout is pretty weird. I would start over. save all data tar/xz. treat everything like a stage3 i want to save, instead of restore.

repartition the disk in a mbr manner, according to your requirements. and just start over with the save as stage 3.
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