Re: [PATCH] block: fix NPE when resuming SCSI devices using blk-mq

[Tomas Janousek]

Hi,

On Fri, Jul 13, 2018 at 09:41:41PM +0800, Ming Lei wrote:
> Now runtime PM is disabled for blk-mq/scsi_mq, not sure how this issue is
> triggered on your machine.

While Patrick did miss the following patch:

* 765e40b675a9 ("block: disable runtime-pm for blk-mq"; July 2017).

there is at least one other way to trigger it -- enable laptop-mode-tools
or tlp which enable runtime-pm for all devices.

The "disable runtime-pm for blk-mq" only disables it _by_default_, but doesn't
prevent it from being enabled again from user-space, which it is unless one
manually blacklists sd devices from runtime-pm enablement. It's bitten a few
people already: https://github.com/rickysarraf/laptop-mode-tools/issues/123

(I found this thread because I'm also getting the NULL pointer dereference at
00000000000001a8 on resume from suspend.)

-- 
TomÃÅ JanouÅek, a.k.a. PivnÃk, a.k.a. Liskni_si, http://work.lisk.in/