Bug 198705

Summary:	mq-bfq breaks usb drives under kernel 4.15.x
Product:	IO/Storage	Reporter:	siyia (eutychios23)
Component:	Other	Assignee:	io_other
Status:	RESOLVED CODE_FIX
Severity:	high	CC:	dan, jbuchert+kbugs, kernel_bugzilla
Priority:	P1
Hardware:	x86-64
OS:	Linux
Kernel Version:	4.15.x	Subsystem:
Regression:	Yes	Bisected commit-id:

Description siyia 2018-02-06 20:52:03 UTC

Hello, under kernel when i am using the mq-bfq i/o scheduler i cannot mount any usb drives and some apps are hanging.This issue is limited only to using mq-bfq scheduler under the 4.15 kernel series,mq-bfq worked fine with 4.14.x and all the other schedulers work properly on 4.15.x.

Comment 1 loqs 2018-02-07 13:43:17 UTC

bisected between 4.14 and 4.15 first bad commit was a6a252e6491443c1c18eab7e254daee63d4a7a04
running blkid the command will hang in the D state on this commit but not its parent if a USB thumb drive is present and the bfq scheduler is used for that device.

Comment 2 loqs 2018-02-08 15:57:19 UTC

Appears to be this issue http://lkml.org/lkml/2018/2/7/529

Comment 3 siyia 2018-02-14 02:34:29 UTC

Resolved in kernel 4.15.3

Comment 4 siyia 2018-02-15 11:32:46 UTC

Reopend only two of my flash drives work with the current state of bfq a data traveller 4.0gb usb2 and a no name 1gb usb2 drive which is weird.

Comment 5 siyia 2018-03-15 04:12:47 UTC

Problem persists with kernel 4.15.8 ,but has been resolved in linux 4.16 mainline since rc1, last time i checked.

Comment 6 siyia 2018-03-19 04:41:23 UTC

Issue resolved under kernel 4.15.10