No subject

[Tim Gardner]

[PATCH 0/1][SRU][jammy:linux-azure, kinetic:linux-azure] 

BugLink: https://bugs.launchpad.net/bugs/1998838

SRU Justification

[Impact]

Hello Canonical Team,

This issue was found while doing the validation on CPC's Jammy CVM image.

While running fio, the command fails to exit after 2 minutes. I watched `top` as the command hung and I saw kworkers getting blocked.

sudo fio --ioengine=libaio --bs=4K --filename=/dev/sdc1:/dev/sdd1:/dev/sde1:/dev/sdf1:/dev/sdg1:/dev/sdh1:/dev/sdi1:/dev/sdj1:/dev/sdk1:/dev/sdl1:/dev/sdm1:/dev/sdn1:/dev/sdo1:/dev/sdp1:/dev/sdq1:/dev/sdr1 --readwrite=randwrite --runtime=120 --iodepth=1 --numjob=96 --name=iteration9 --direct=1 --size=8192M --group_reporting --overwrite=1

Example system logs:
---------------------------------------------------------------------------------------------------------------
[ 1096.297641] INFO: task kworker/u192:0:8 blocked for more than 120 seconds.
[ 1096.302785] Tainted: G W 5.15.0-1024-azure #30-Ubuntu
[ 1096.306312] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1096.310489] INFO: task jbd2/sda1-8:1113 blocked for more than 120 seconds.
[ 1096.313900] Tainted: G W 5.15.0-1024-azure #30-Ubuntu
[ 1096.317481] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1096.324117] INFO: task systemd-journal:1191 blocked for more than 120 seconds.
[ 1096.331219] Tainted: G W 5.15.0-1024-azure #30-Ubuntu
[ 1096.335332] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
---------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------
[ 3241.013230] systemd-udevd[1221]: sdl1: Worker [6686] processing SEQNUM=13323 killed
[ 3261.492691] systemd-udevd[1221]: sdl1: Worker [6686] failed
---------------------------------------------------------------------------------------------------------------

TOP report:
---------------------------------------------------------------------------------------------------------------
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
417 root 20 0 0 0 0 R 66.2 0.0 0:34.61 ksoftirqd/59
435 root 20 0 0 0 0 I 24.5 0.0 0:09.03 kworker/59:1-mm_percpu_wq
416 root rt 0 0 0 0 S 23.5 0.0 0:01.86 migration/59
366 root 0 -20 0 0 0 I 19.2 0.0 0:16.64 kworker/49:1H-kblockd
378 root 0 -20 0 0 0 I 17.9 0.0 0:15.71 kworker/51:1H-kblockd
455 root 0 -20 0 0 0 I 17.9 0.0 0:14.76 kworker/62:1H-kblockd
135 root 0 -20 0 0 0 I 17.5 0.0 0:13.08 kworker/17:1H-kblockd
420 root 0 -20 0 0 0 I 16.9 0.0 0:14.63 kworker/58:1H-kblockd
...
---------------------------------------------------------------------------------------------------------------

LISAv3 Testcase: perf_premium_datadisks_4k
Image : "canonical-test 0001-com-ubuntu-confidential-vm-jammy-preview 22_04-lts-cvm latest"
VMSize : "Standard_DC96ads_v5"

For repro-ability, I am seeing this every time I run the storage perf tests. It always seems to happen on iteration
9 or 10. When running manually, I had to run the command three or four times to reproduce the issue.

[Test Case]

Microsoft tested, requires lots of cores (96) and disks (16)

[Where things could go wrong]

swiotlb buffers could be double freed.

[Other Info]

SF: #00349781