Re: problem booting 5.10

[Linus Torvalds <torvalds@linux-foundation.org>]

On Tue, Dec 8, 2020 at 9:37 AM Julia Lawall <julia.lawall@inria.fr> wrote:
>
> We have not succeeded to boot 5.10 on our Intel(R) Xeon(R) CPU E7-8870 v4 @
> 2.10GHz server.  Previous versions (eg 4.19 - 5.9) boot fine.  We have
> tried various rcs.

So the problem started with rc1?

Could you try bisecting - even partially? If you do only six
bisections, the number of suspect commits drops from 15k to about 230
- which likely pinpoints the suspect area.

That said, your traces certainly makes me go "Hmm. Some thing broke in
SCSI device scanning", with the primary one being the
wait_for_completion() one - the rest of the stuck processes seem to be
stuck in async_synchronize_cookie_domain() and are presumably waiting
for this kthread that is waiting for the scan to finish.

So I'm adding SCSI people to the cc, just in case they go "Hmm..".

Martin & co - in the next email Julia also quotes

> [   51.355655][    T7] scsi 0:0:14:0: Direct-Access     ATA      ST2000LM015-2E81 SDM1 PQ: 0 ANSI: 6
> Gave up waiting for root file system device.  Common problems:[..]

which seems to be more of the same pattern with the SCSI scanning failure.

Of course, it could be some non-scsi patch that causes this, but.. A
bisect would hopefully clarify.

Leaving the (simplified) backtrace quoted below.

                   Linus

>The backtrace for rc7 is shown below.
>
> [  253.207171][  T979] INFO: task kworker/u321:2:1278 blocked for more than 120 seconds.
> [  253.224089][  T979]       Tainted: G            E     5.10.0-rc7 #3
> [  253.239209][  T979] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [  253.256990][  T979] task:kworker/u321:2  state:D stack:    0 pid: 1278 ppid:     2 flags:0x00004000
> [  253.275552][  T979] Workqueue: events_unbound async_run_entry_fn
> [  253.290687][  T979] Call Trace:
> [  253.302491][  T979]  __schedule+0x31e/0x890
> [  253.315353][  T979]  schedule+0x3c/0xa0
> [  253.327688][  T979]  schedule_timeout+0x274/0x310
> [  253.379283][  T979]  wait_for_completion+0x8a/0xf0
> [  253.392327][  T979]  scsi_complete_async_scans+0x107/0x170
> [  253.406115][  T979]  __scsi_add_device+0xf7/0x130
> [  253.418974][  T979]  ata_scsi_scan_host+0x98/0x1c0
> [  253.431948][  T979]  async_run_entry_fn+0x39/0x160
> [  253.444853][  T979]  process_one_work+0x24c/0x490