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