Re: Regression 4.17-rc1: SSD doesnât properly resume causing system hang (NULL pointer dereference)

From: Paul Menzel
Date: Wed Apr 25 2018 - 08:35:01 EST


Dear Bart,


On 04/25/18 14:26, Bart Van Assche wrote:
On Wed, 2018-04-25 at 07:37 +0200, Paul Menzel wrote:
Am 24.04.2018 um 23:17 schrieb Bart Van Assche:
On Tue, 2018-04-24 at 23:04 +0200, Paul Menzel wrote:
I applied your change, and rebuilt the Linux kernel. Unfortunately, it
looks like, it didnât make a difference.

In that case I don't know what is causing the failure. Can you run a bisect
to determine which commit introduced this regression?

With `scsi_mod.use_blk_mq=n` the system resumes fine, so for to me
unknown reasons, that Kconfig option get selected in my Linux kernel
configuration. I remember having similar issues when this was enabled by
default in Linux 4.13-rc?, so it was just a configuration problem and
not a regression. Unfortunately, the Linux configuration files are not
under version control, so I cannot check, but it is probably my fault.

Sorry for the noise, and please tell me, what I can do to get the option
working on this old device.

Did the same system boot fine with a previous kernel with scsi-mq enabled?

No, as far as I know it never worked, see thread *[Regression 4.13-rc1] Resume does not work on Lenovo X60t* [1].

Anyway, we would like to know what is the root cause such that this NULL
pointer dereference can be fixed. There are namely plans to remove the
legacy block layer in the not too distant future.

Iâll be happy to test proposed changes.


Kind regards,

Paul


PS: Your mailer also changed *doesnât* to *doesn* in the subject line.


[1] https://www.spinics.net/lists/linux-scsi/msg111457.html

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