Arch Linux

EduAlmeida

Member

Registered: 2016-12-19

Posts: 11

Processes in D state after update to 4.19.4

I'm using Arch Linux (as a home server), and after updating to `4.19.4` (from `4.19.2`), I started having problems where processes trying to access data on /dev/md127 (my raid1, mounted at /home) would get stalled in D state for a few minutes up to a few hours, after which everything would go back to normal. Since it's mounted at /home, even trying to SSH in would leave me not being able to do anything, since the shell starts on my home folder.

I have more disks on that server (but only those two as raid1), and those are the only ones that suffer from that problem.

I beleive this is caused by that kernel version, since I've installed `4.9 LTS` and that has been working just fine for the past few days... But it's weird that the problem persists even on `4.19.12`, which is a few versions ahead the one where my problems started.

Is there anything I can do to debug this?

Thanks in advance.

loqs

Member

Registered: 2014-03-06

Posts: 18,931

Re: Processes in D state after update to 4.19.4

I would suggest either testing if 4.19.3 is affected then bisect between the affected and unaffected stable releases or trying 4.20.

stronnag

Member

Registered: 2011-01-25

Posts: 77

Re: Processes in D state after update to 4.19.4

Don't use the new multi-threaded scehduler /queue (mq) stuff which is now the default; it really does not live well with raid1.
Addding:

scsi_mod.use_blk_mq=0 

to the kernel options in the boot loaded should fix it.

EduAlmeida

Member

Registered: 2016-12-19

Posts: 11

Re: Processes in D state after update to 4.19.4

Don't use the new multi-threaded scehduler /queue (mq) stuff which is now the default; it really does not live well with raid1.
Addding:

scsi_mod.use_blk_mq=0 

to the kernel options in the boot loaded should fix it.

Trying that, fingers crossed, thanks!

Last edited by EduAlmeida (2018-12-26 19:31:43)

stronnag

Member

Registered: 2011-01-25

Posts: 77

Re: Processes in D state after update to 4.19.4

The new kernel 4.20.0-arch1 seems so far to have solved the problem as well, with mq-deadline on RAID1

stronnag

Member

Registered: 2011-01-25

Posts: 77

Re: Processes in D state after update to 4.19.4

Too soon. First 5 minute D state hang on 4.20 with  mq; back to

scsi_mod.use_blk_mq=0

loqs

Member

Registered: 2014-03-06

Posts: 18,931

Re: Processes in D state after update to 4.19.4

@stronnag you might want to work with upstream to resolve the issue before 4.21 introduces https://git.kernel.org/pub/scm/linux/ke … 029b0ec0e6