This test exposed a race condition with shutting down a request_queue and the new blkg association. The issue ended up being that while the request_queue will just start failing requests, blkg destruction sets the q->root_blkg to %NULL. This caused a NPE when trying to reference it. So to help prevent this from happening again, integrate Ming's test into blktests so that it can more easily be ran.
Signed-off-by: Dennis Zhou <[email protected]> Cc: Ming Lei <[email protected]> --- v2: - Change scheduler retrieving logic based on Ming's comment tests/block/022 | 90 +++++++++++++++++++++++++++++++++++++++++++++ tests/block/022.out | 2 + 2 files changed, 92 insertions(+) create mode 100755 tests/block/022 create mode 100644 tests/block/022.out diff --git a/tests/block/022 b/tests/block/022 new file mode 100755 index 0000000..84336e0 --- /dev/null +++ b/tests/block/022 @@ -0,0 +1,90 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-3.0+ +# Copyright (C) 2018 Ming Lei +# +# Regression test for patch "blkcg: handle dying request_queue when associating +# a blkg" +# +# This tries to expose the race condition between blkg association and +# request_queue shutdown. When a request_queue is shutdown, the corresponding +# blkgs are destroyed. Any further associations should fail gracefully and not +# cause a kernel panic. + +. tests/block/rc +. common/scsi_debug +. common/cgroup + +DESCRIPTION="test graceful shutdown of scsi_debug devices with running fio jobs" +QUICK=1 + +requires() { + _have_cgroup2_controller io && _have_scsi_debug && _have_fio +} + +scsi_debug_stress_remove() { + scsi_debug_path="/sys/bus/pseudo/drivers/scsi_debug" + count=21 + + runtime=12 + nr_fio_jobs=8 + scsi_dbg_ndelay=10000 + + # set higher aio limit + echo 524288 > /proc/sys/fs/aio-max-nr + + #figure out the CAN_QUEUE + can_queue=$(((count + 1) * (count / 2) / 2)) + + rmmod scsi_debug > /dev/null 2>&1 + modprobe scsi_debug virtual_gb=128 max_luns=$count \ + ndelay=$scsi_dbg_ndelay max_queue=$can_queue + + # figure out scsi_debug disks + hosts=$(ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter0/host*) + hostname=$(basename "$hosts") + host=$(echo "$hostname" | grep -o -E '[0-9]+') + + sdisks=$(ls -d $scsi_debug_path/adapter*/"$hostname"/target*/*/block/*) + disks="" + for sd in $sdisks; do + disks+="/dev/"$(basename "$sd") + disks+=" " + done + + fio_jobs="" + cnt=0 + for sd in $disks; do + cnt=$((cnt+1)) + fio_jobs=$fio_jobs" --name=job1 --filename=$sd: " + dev_name=$(basename "$sd") + q_path=/sys/block/$dev_name/queue + + scheds=($(sed 's/[][]//g' "$q_path/scheduler")) + sched_idx=$((cnt % ${#scheds[@]})) + echo "${scheds[$sched_idx]}" > "$q_path/scheduler" + echo $cnt > "$q_path/../device/queue_depth" + done + + fio --rw=randread --size=128G --direct=1 --ioengine=libaio \ + --iodepth=2048 --numjobs=$nr_fio_jobs --bs=4k \ + --group_reporting=1 --group_reporting=1 --runtime=$runtime \ + --loops=10000 "$fio_jobs" > "$FULL" 2>&1 & + + sleep 7 + for sd in $disks; do + dev_name=$(basename "$sd") + dpath=/sys/block/$dev_name/device + [ -f "$dpath/delete" ] && echo 1 > "$dpath/delete" + done + + wait +} + + +test() { + echo "Running ${TEST_NAME}" + + scsi_debug_stress_remove + + echo "Test complete" +} diff --git a/tests/block/022.out b/tests/block/022.out new file mode 100644 index 0000000..14d43cb --- /dev/null +++ b/tests/block/022.out @@ -0,0 +1,2 @@ +Running block/022 +Test complete -- 2.17.1
