Write I/O queue hangup at random on recent Linus' kernels

[Kenneth R. Crudup]

On Thu, 2 Dec 2021, Kenneth R. Crudup wrote:

>   $ egrep -r . $(sudo find /sys/block/*/ -name inflight )
>
> ... but they were all zeros.

... and similarly:

----
$ sudo egrep -r . $(sudo find /sys/kernel/debug/block/ -name inflight)
/sys/kernel/debug/block/mmcblk0/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/mmcblk0/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/mmcblk0/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/sda/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/sda/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/sda/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/nvme0n1/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/nvme0n1/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/nvme0n1/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/loop7/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/loop7/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/loop7/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/loop6/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/loop6/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/loop6/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/loop5/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/loop5/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/loop5/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/loop4/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/loop4/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/loop4/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/loop3/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/loop3/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/loop3/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/loop2/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/loop2/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/loop2/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/loop1/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/loop1/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/loop1/rqos/wbt/inflight:2: inflight 0
/sys/kernel/debug/block/loop0/rqos/wbt/inflight:0: inflight 0
/sys/kernel/debug/block/loop0/rqos/wbt/inflight:1: inflight 0
/sys/kernel/debug/block/loop0/rqos/wbt/inflight:2: inflight 0
----

(... but just now, I got a delayed popup from my UI, which then went back to
being unresponsive again)

	-Kenny

-- 
Kenneth R. Crudup / Sr. SW Engineer, Scott County Consulting, Orange County CA