Re: Regression v6.11 booting cannot mount harddisks (xfs)

Damien Le Moal
2024-09-10T13:06:27Z

On 2024/09/10 21:19, Jesper Dangaard Brouer wrote:
> Hi Linus,
>
> My testlab kernel devel server isn't booting correctly on v6.11 branches
> (e.g. net-next at 6.11.0-rc5)
> I just confirmed this also happens on your tree tag: v6.11-rc7.
>
> The symptom/issue is that harddisk dev names (e.g /dev/sda, /dev/sdb,
> /dev/sdc) gets reordered. I switched /etc/fstab to use UUID's instead
> (which boots on v6.10) but on 6.11 it still cannot mount harddisks and
> doesn't fully boot.

Parallel SCSI device scanning has been around for a long time... This is
controlled with CONFIG_SCSI_SCAN_ASYNC. And yes, that can cause disk names to
change, which is why it is never a good idea to rely on them but instead use
/dev/disk/by-* names. Disabling CONFIG_SCSI_SCAN_ASYNC will likely not guarantee
that disk names will be constant, given that you seem to have 2 AHCI adapters on
your host and PCI device scanning is done in parallel.

> E.g. errors:
> systemd[1]: Expecting device
> dev-disk-by\x2duuid-0c2b348d\x2de013\x2d482b\x2da91c\x2d029640ec427a.device
> - /dev/disk/by-uuid/0c2b348d-e013-482b-a91c-029640ec42
> 7a...
> [DEPEND] Dependency failed for var-lib.mount - /var/lib.
> [...]
> [ TIME ] Timed out waiting for device
> dev-d…499e46-b40d-4067-afd4-5f6ad09fcff2.
> [DEPEND] Dependency failed for boot.mount - /boot.
>
> That corresponds to fstab's:
> - UUID=8b499e46-b40d-4067-afd4-5f6ad09fcff2 /boot xfs defaults 0 0
> - UUID=0c2b348d-e013-482b-a91c-029640ec427a /var/lib/ xfs defaults 0 0
>
> It looks like disk controller initialization happens in *parallel* on
> these newer kernels as dmesg shows init printk's overlapping:
>
> [ 5.683393] scsi 5:0:0:0: Direct-Access ATA SAMSUNG
> MZ7KM120 003Q PQ: 0 ANSI: 5
> [ 5.683641] scsi 7:0:0:0: Direct-Access ATA SAMSUNG
> MZ7KM120 003Q PQ: 0 ANSI: 5
> [ 5.683797] scsi 8:0:0:0: Direct-Access ATA Samsung SSD
> 840 BB0Q PQ: 0 ANSI: 5
> [...]
> [ 7.057376] sd 5:0:0:0: [sda] 234441648 512-byte logical blocks:
> (120 GB/112 GiB)
> [ 7.062279] sd 7:0:0:0: [sdb] 234441648 512-byte logical blocks:
> (120 GB/112 GiB)
> [ 7.070628] sd 5:0:0:0: [sda] Write Protect is off
> [ 7.070701] sd 8:0:0:0: [sdc] 488397168 512-byte logical blocks:
> (250 GB/233 GiB)
>
> Perhaps this could be a hint to what changed?

See above. The disk /dev/sdX names not being reliable is rather normal.
Are you sure you have the correct UUIDs of your FSes on the disks ? You can
check them with "blkid /dev/sdX[n]"

> Any hints what commit I should try to test revert?
> Or good starting point for bisecting?

You said that 6.10 works, so maybe start from there ?

--
Damien Le Moal
Western Digital Research