Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 17 Oct 2022 17:25:37 +0800
From:   Ming Lei <ming.lei@redhat.com>
To:     Chaitanya Kulkarni <kch@nvidia.com>
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        axboe@kernel.dk, damien.lemoal@opensource.wdc.com,
        johannes.thumshirn@wdc.com, bvanassche@acm.org,
        shinichiro.kawasaki@wdc.com, vincent.fu@samsung.com,
        yukuai3@huawei.com
Subject: Re: [PATCH] null_blk: allow teardown on request timeout
Message-ID: <Y00fkc1N+Cif/Kxt@T590>
References: <20221016052006.11126-1-kch@nvidia.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20221016052006.11126-1-kch@nvidia.com>
Precedence: bulk

On Sat, Oct 15, 2022 at 10:20:06PM -0700, Chaitanya Kulkarni wrote:
> In current timeout implementation null_blk just completes the request
> with error=BLK_STS_TIMEOUT without doing any cleanup, hence device
> cleanup code including handling inflight requests on timeout and
> teardown is never exercised.
> 
> Add a module parameter rq_abort_limit to allow null_blk perform device
> cleanup when time out occurs. The non zero value of this parameter
> allows user to set the number of timeouts to occur before triggering
> cleanup/teardown work.
> 
> Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
> ---
> * Test result enabling the rq_abort_limit from module parameter and
>   issueing dd until null_blk device disappears from the pathname
>   with connetion timeout error.
>  
> linux-block (for-next) # !./test_
> ./test_null_blk_abort_on_timeout.sh 
> commit 4fbcf978ae8f385aa1830ce40f210c7eec8d58fa (HEAD -> for-next)
> Author: Chaitanya Kulkarni <kch@nvidia.com>
> Date:   Tue Oct 11 23:22:43 2022 -0700
> 
>     null_blk: allow teardown on request timeout
>     
>     In current timeout implementation null_blk just completes the request
>     with error=BLK_STS_TIMEOUT without doing any cleanup, hence device
>     cleanup code including handling inflight requests on timeout and
>     teardown is never exercised.
>     
>     Add a module parameter rq_abort_limit to allow null_blk perform device
>     cleanup when time out occurs. The non zero value of this parameter
>     allows user to set the number of timeouts to occur before triggering
>     cleanup/teardown work.
>     
>     Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
> + umount /mnt/nullb0
> umount: /mnt/nullb0: not mounted.
> + rmdir 'config/nullb/nullb*'
> rmdir: failed to remove 'config/nullb/nullb*': No such file or directory
> + dmesg -c
> + modprobe -r null_blk
> + lsmod
> + grep null_blk
> ++ nproc
> + make -j 48 M=drivers/block modules
>   CC [M]  drivers/block/null_blk/main.o
>   CC [M]  drivers/block/null_blk/trace.o
>   CC [M]  drivers/block/null_blk/zoned.o
>   LD [M]  drivers/block/null_blk/null_blk.o
>   MODPOST drivers/block/Module.symvers
>   LD [M]  drivers/block/null_blk/null_blk.ko
> + HOST=drivers/block/null_blk/
> ++ uname -r
> + HOST_DEST=/lib/modules/6.0.0blk+/kernel/drivers/block/null_blk/
> + cp drivers/block/null_blk//null_blk.ko /lib/modules/6.0.0blk+/kernel/drivers/block/null_blk//
> + ls -lrth /lib/modules/6.0.0blk+/kernel/drivers/block/null_blk//null_blk.ko
> -rw-r--r--. 1 root root 1.2M Oct 15 21:51 /lib/modules/6.0.0blk+/kernel/drivers/block/null_blk//null_blk.ko
> + sleep 1
> + dmesg -c
> ##################
> ##################
> nullb0  250:0    0  250G  0 disk 
> dd: error writing '/dev/nullb0': Connection timed out
> 3+0 records in
> 2+0 records out
> 8192 bytes (8.2 kB, 8.0 KiB) copied, 6.13436 s, 1.3 kB/s
> ##################
> ##################
> nullb0  250:0    0  250G  0 disk 
> [ 1598.393544] null_blk: rq 0000000015ff5165 timed out
> [ 1598.393555] blk_print_req_error: 74 callbacks suppressed
> [ 1598.393558] timeout error, dev nullb0, sector 8 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1598.395885] Buffer I/O error on dev nullb0, logical block 1, async page read
> [ 1598.397731] Dev nullb0: unable to read RDB block 8
> [ 1598.398990]  nullb0: unable to read partition table
> [ 1598.399069] null_blk: disk nullb0 created
> [ 1598.399071] null_blk: module loaded
> [ 1604.537424] null_blk: rq 00000000b2a753f0 timed out
> [ 1604.537437] timeout error, dev nullb0, sector 16 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> dd: error writing '/dev/nullb0': Connection timed out
> 1+0 records in
> 0+0 records out
> 0 bytes copied, 6.13561 s, 0.0 kB/s
> ##################
> ##################
> nullb0  250:0    0  250G  0 disk 
> [ 1610.681242] null_blk: rq 00000000a392790b timed out
> [ 1610.681253] timeout error, dev nullb0, sector 0 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> dd: error writing '/dev/nullb0': Connection timed out
> 1+0 records in
> 0+0 records out
> 0 bytes copied, 6.13985 s, 0.0 kB/s
> ##################
> ##################
> nullb0  250:0    0  250G  0 disk 
> [ 1616.825155] null_blk: rq 0000000091a70f01 timed out
> [ 1616.825168] timeout error, dev nullb0, sector 0 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> dd: error writing '/dev/nullb0': Connection timed out
> 1+0 records in
> 0+0 records out
> 0 bytes copied, 6.1325 s, 0.0 kB/s
> ##################
> ##################
> nullb0  250:0    0  250G  0 disk 
> [ 1622.969017] null_blk: rq 00000000cdb610e7 timed out
> [ 1622.969029] timeout error, dev nullb0, sector 0 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> dd: error writing '/dev/nullb0': Connection timed out
> 2+0 records in
> 1+0 records out
> 4096 bytes (4.1 kB, 4.0 KiB) copied, 6.14283 s, 0.7 kB/s
> ##################
> ##################
> [ 1629.112893] null_blk: rq 00000000555ecc5e timed out
> [ 1629.118817] blk_sync_queue 230
> [ 1629.118821] blk_sync_queue 232
> [ 1629.118823] blk_sync_queue 234
> [ 1629.118828] timeout error, dev nullb0, sector 8 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> [ 1629.125044] blk_sync_queue 230
> [ 1629.125048] blk_sync_queue 232
> [ 1629.125049] blk_sync_queue 234
> ##################
> ##################
> 
> * Test result enabling the rq_abort_limit from module parameter and
>   issueing fio until null_blk device disappears from the pathname
>   with connetion timeout error.
> nullb0  250:0    0  250G  0 disk 
> RANDREAD: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=128
> fio-3.27
> Starting 1 process
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=214274048, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=32268288, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=107802624, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=193708032, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=202928128, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=281436160, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=33292288, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=250576896, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=41902080, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=225521664, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=303058944, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=405196800, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=309719040, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=111214592, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=254062592, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=128663552, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=76795904, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=355647488, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=5873664, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=69328896, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=216276992, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=16027648, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=328343552, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=385630208, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=137695232, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=146546688, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=157765632, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=290615296, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=230440960, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=130961408, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=88547328, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=157401088, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=296202240, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=35819520, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=212545536, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=261697536, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=66195456, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=254603264, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=169242624, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=258154496, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=69320704, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=335650816, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=192950272, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=32813056, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=5804032, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=217219072, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=153227264, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=91131904, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=241209344, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=246509568, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=332935168, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=108859392, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=86061056, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=278966272, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=219004928, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=290512896, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=143306752, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=176312320, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=346566656, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=183422976, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=383885312, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=199393280, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=160944128, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=142491648, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=217841664, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=178466816, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=331423744, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=88883200, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=311562240, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=228642816, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=362893312, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=323035136, buflen=4096
> fio: io_u error on file /dev/nullb0: Input/output error: read offset=385089536, buflen=4096
> fio: pid=7811, err=110/file:io_u.c:1841, func=io_u error, error=Connection timed out
> 
> RANDREAD: (groupid=0, jobs=1): err=110 (file:io_u.c:1841, func=io_u error, error=Connection timed out): pid=7811: Sat Oct 15 21:52:09 2022
>   read: IOPS=33, BW=64.6KiB/s (66.1kB/s)(420KiB/6503msec)
>     slat (nsec): min=942, max=6485.4M, avg=29824299.02, stdev=439245367.62
>     clat (usec): min=525, max=6501.3k, avg=3899782.52, stdev=3194606.52
>      lat (usec): min=530, max=6501.3k, avg=3961597.01, stdev=3181404.42
>     clat percentiles (usec):
>      |  1.00th=[    545],  5.00th=[    553], 10.00th=[    562],
>      | 20.00th=[    611], 30.00th=[  15795], 40.00th=[  15795],
>      | 50.00th=[6476006], 60.00th=[6476006], 70.00th=[6476006],
>      | 80.00th=[6476006], 90.00th=[6476006], 95.00th=[6476006],
>      | 99.00th=[6476006], 99.50th=[6476006], 99.90th=[6476006],
>      | 99.95th=[6476006], 99.99th=[6476006]
>    bw (  KiB/s): min=  216, max=  216, per=100.00%, avg=216.00, stdev= 0.00, samples=1
>    iops        : min=   54, max=   54, avg=54.00, stdev= 0.00, samples=1
>   lat (usec)   : 750=12.39%
>   lat (msec)   : 20=6.88%, >=2000=28.90%
>   cpu          : usr=0.00%, sys=0.00%, ctx=4, majf=0, minf=150
>   IO depths    : 1=0.5%, 2=0.9%, 4=1.8%, 8=3.7%, 16=7.3%, 32=14.7%, >=64=71.1%
>      submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
>      complete  : 0=0.0%, 4=98.9%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=1.1%
>      issued rwts: total=218,0,0,0 short=40,0,0,0 dropped=0,0,0,0
>      latency   : target=0, window=0, percentile=100.00%, depth=128
> 
> Run status group 0 (all jobs):
>    READ: bw=64.6KiB/s (66.1kB/s), 64.6KiB/s-64.6KiB/s (66.1kB/s-66.1kB/s), io=420KiB (430kB), run=6503-6503msec
> 
> Disk stats (read/write):
>   nullb0: ios=90/0, merge=0/0, ticks=0/0, in_queue=0, util=98.55%
> ##################
> ##################
> [ 1635.256737] null_blk: rq 00000000834b8ba3 timed out
> [ 1635.256748] timeout error, dev nullb0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1635.258876] Buffer I/O error on dev nullb0, logical block 0, async page read
> [ 1641.400625] null_blk: rq 00000000ee97fbff timed out
> [ 1641.400636] timeout error, dev nullb0, sector 8 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1641.402919] Buffer I/O error on dev nullb0, logical block 1, async page read
> [ 1641.404755] Dev nullb0: unable to read RDB block 8
> [ 1641.406666]  nullb0: unable to read partition table
> [ 1641.407559] null_blk: disk nullb0 created
> [ 1641.407562] null_blk: module loaded
> [ 1648.056420] null_blk: rq 00000000834b8ba3 timed out
> [ 1648.056432] timeout error, dev nullb0, sector 418504 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.058914] null_blk: rq 0000000064c974a9 timed out
> [ 1648.058918] timeout error, dev nullb0, sector 63024 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.061288] null_blk: rq 00000000ee97fbff timed out
> [ 1648.061291] timeout error, dev nullb0, sector 210552 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.063663] null_blk: rq 000000006c6fa717 timed out
> [ 1648.063667] timeout error, dev nullb0, sector 378336 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.066011] null_blk: rq 00000000fa856166 timed out
> [ 1648.066015] null_blk: rq 00000000de9bec9a timed out
> [ 1648.066016] timeout error, dev nullb0, sector 396344 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.068390] null_blk: rq 00000000f12b4b17 timed out
> [ 1648.068393] timeout error, dev nullb0, sector 549680 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.071389] null_blk: rq 00000000667726b2 timed out
> [ 1648.071393] timeout error, dev nullb0, sector 65024 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.073740] null_blk: rq 0000000088f0f903 timed out
> [ 1648.073744] timeout error, dev nullb0, sector 489408 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.078759] null_blk: rq 00000000fd349776 timed out
> [ 1648.078762] timeout error, dev nullb0, sector 81840 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.081093] null_blk: rq 000000002eb20dc4 timed out
> [ 1648.081096] timeout error, dev nullb0, sector 440472 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.083492] null_blk: rq 000000002db4026f timed out
> [ 1648.083496] null_blk: rq 00000000db8f8be3 timed out
> [ 1648.083499] null_blk: rq 00000000078a6daf timed out
> [ 1648.083502] null_blk: rq 000000002c1b7c68 timed out
> [ 1648.083505] null_blk: rq 00000000790d87a1 timed out
> [ 1648.083508] null_blk: rq 000000004f48b7de timed out
> [ 1648.083516] null_blk: rq 0000000074a5ff86 timed out
> [ 1648.083518] null_blk: rq 000000000daf10f8 timed out
> [ 1648.083521] null_blk: rq 00000000d54f527e timed out
> [ 1648.083523] null_blk: rq 0000000009dc7bb8 timed out
> [ 1648.083526] null_blk: rq 0000000017e81cd2 timed out
> [ 1648.083529] null_blk: rq 0000000088e83fa2 timed out
> [ 1648.083532] null_blk: rq 000000003c014afe timed out
> [ 1648.083534] null_blk: rq 00000000b7a99358 timed out
> [ 1648.083537] null_blk: rq 00000000d2d80485 timed out
> [ 1648.083539] null_blk: rq 000000008805db58 timed out
> [ 1648.083541] null_blk: rq 000000005c2e8f7a timed out
> [ 1648.083544] null_blk: rq 00000000a33a2f2d timed out
> [ 1648.083546] null_blk: rq 00000000d05bf454 timed out
> [ 1648.083549] null_blk: rq 0000000080cb849f timed out
> [ 1648.083552] null_blk: rq 000000009cbb48e0 timed out
> [ 1648.083555] null_blk: rq 000000009e426689 timed out
> [ 1648.083558] null_blk: rq 000000003705d117 timed out
> [ 1648.083561] null_blk: rq 0000000010bc80b4 timed out
> [ 1648.083563] null_blk: rq 000000004da816da timed out
> [ 1648.083566] null_blk: rq 0000000081ceaf3f timed out
> [ 1648.083568] null_blk: rq 00000000fb1e808e timed out
> [ 1648.083570] null_blk: rq 000000006baf39c2 timed out
> [ 1648.083573] null_blk: rq 00000000241e851f timed out
> [ 1648.083575] null_blk: rq 00000000a7b7ff27 timed out
> [ 1648.083577] null_blk: rq 0000000092e37377 timed out
> [ 1648.083580] null_blk: rq 00000000a2b070cd timed out
> [ 1648.083583] null_blk: rq 00000000a2c63d6f timed out
> [ 1648.083585] null_blk: rq 00000000b775711d timed out
> [ 1648.083588] null_blk: rq 000000000bfe50e6 timed out
> [ 1648.083590] null_blk: rq 000000005c0b7039 timed out
> [ 1648.083593] null_blk: rq 00000000af60d454 timed out
> [ 1648.083595] null_blk: rq 00000000d2a38d75 timed out
> [ 1648.083598] null_blk: rq 0000000000ae81a8 timed out
> [ 1648.083601] null_blk: rq 000000001974c62a timed out
> [ 1648.083603] null_blk: rq 000000002aaf80e6 timed out
> [ 1648.083605] null_blk: rq 00000000bcdf1c85 timed out
> [ 1648.083608] null_blk: rq 000000008b5d9eb6 timed out
> [ 1648.083610] null_blk: rq 0000000066fcf345 timed out
> [ 1648.083613] null_blk: rq 0000000067dc1221 timed out
> [ 1648.083615] null_blk: rq 0000000088e78508 timed out
> [ 1648.083618] null_blk: rq 000000009d1352eb timed out
> [ 1648.083620] null_blk: rq 00000000a7019839 timed out
> [ 1648.083622] null_blk: rq 00000000f5756a31 timed out
> [ 1648.083625] null_blk: rq 00000000841b16a6 timed out
> [ 1648.083627] null_blk: rq 0000000082fa3e11 timed out
> [ 1648.083630] null_blk: rq 00000000794e9904 timed out
> [ 1648.083632] null_blk: rq 00000000c3bcf5d1 timed out
> [ 1648.094395] blk_sync_queue 230
> [ 1648.094400] blk_sync_queue 232
> [ 1648.094402] blk_sync_queue 234
> [ 1648.096130] blk_sync_queue 230
> [ 1648.096133] blk_sync_queue 232
> [ 1648.096135] blk_sync_queue 234
> NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
> sda       8:0    0   50G  0 disk 
> ├─sda1    8:1    0    1G  0 part /boot
> └─sda2    8:2    0   49G  0 part /home
> sdb       8:16   0  100G  0 disk /mnt/data
> sr0      11:0    1 1024M  0 rom  
> zram0   251:0    0    8G  0 disk [SWAP]
> ---
>  drivers/block/null_blk/main.c     | 90 +++++++++++++++++++++++++++++--
>  drivers/block/null_blk/null_blk.h | 10 ++++
>  2 files changed, 97 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 1f154f92f4c2..52db6b99b448 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -77,6 +77,10 @@ enum {
>  	NULL_IRQ_TIMER		= 2,
>  };
>  
> +static unsigned int g_rq_abort_limit = 5;
> +module_param_named(rq_abort_limit, g_rq_abort_limit, uint, 0644);
> +MODULE_PARM_DESC(rq_abort_limit, "request timeout teardown limit. Default:5");
> +
>  static bool g_virt_boundary = false;
>  module_param_named(virt_boundary, g_virt_boundary, bool, 0444);
>  MODULE_PARM_DESC(virt_boundary, "Require a virtual boundary for the device. Default: False");
> @@ -247,6 +251,7 @@ static void null_del_dev(struct nullb *nullb);
>  static int null_add_dev(struct nullb_device *dev);
>  static struct nullb *null_find_dev_by_name(const char *name);
>  static void null_free_device_storage(struct nullb_device *dev, bool is_cache);
> +static void null_destroy_dev(struct nullb *nullb);
>  
>  static inline struct nullb_device *to_nullb_device(struct config_item *item)
>  {
> @@ -578,6 +583,18 @@ config_item *nullb_group_make_item(struct config_group *group, const char *name)
>  {
>  	struct nullb_device *dev;
>  
> +	if (g_rq_abort_limit) {
> +		/*
> +		 * abort_on_timeout removes the null_blk and resources. When
> +		 * null_blk is created using configfs entry by user we will also
> +		 * need to cleanup the those entries when abort_on_timeout is set
> +		 * from null_abort_work() and that we shold not do it, since
> +		 * manupulating user's entries from kernel can create confusion,
> +		 * so just don't allow it.
> +		 */
> +		pr_err("don't use g_abort_on_timeout with configfs entries\n");
> +		return ERR_PTR(-EINVAL);
> +	}
>  	if (null_find_dev_by_name(name))
>  		return ERR_PTR(-EEXIST);
>  
> @@ -614,7 +631,7 @@ static ssize_t memb_group_features_show(struct config_item *item, char *page)
>  			"poll_queues,power,queue_mode,shared_tag_bitmap,size,"
>  			"submit_queues,use_per_node_hctx,virt_boundary,zoned,"
>  			"zone_capacity,zone_max_active,zone_max_open,"
> -			"zone_nr_conv,zone_size\n");
> +			"zone_nr_conv,zone_size,abort_on_timeout,rq_abort_limit\n");
>  }
>  
>  CONFIGFS_ATTR_RO(memb_group_, features);
> @@ -1609,10 +1626,60 @@ static int null_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob)
>  	return nr;
>  }
>  
> +static bool null_cancel_request(struct request *rq, void *data)
> +{
> +	struct nullb_cmd *cmd = blk_mq_rq_to_pdu(rq);
> +
> +	/*
> +	 * Keep it simple and set the timeout error since we've been schedule
> +	 * from timeout handler afterall.
> +	 */
> +	cmd->error = BLK_STS_TIMEOUT;
> +	if (blk_mq_request_started(rq) && !blk_mq_request_completed(rq))
> +		blk_mq_complete_request(rq);
> +	return true;
> +}
> +
> +static void null_abort_work(struct work_struct *w)
> +{
> +	struct nullb *nullb = container_of(w, struct nullb, abort_work);
> +
> +	mutex_lock(&lock);
> +	if (!nullb || !nullb->dev)
> +		goto unlock;
> +
> +	/*
> +	 * To make sure that null_handle_cmd() callers are not in progress from
> +	 * null_queue_rq()/null_submit_bio() when we are stopping nullb, we
> +	 * quiece the block layer request queue and engage in teardown sequence.
> +	 */
> +	blk_freeze_queue_start(nullb->q);
> +	blk_mq_quiesce_queue(nullb->q);
> +	/*
> +	 * We already ensured that submit_bio() will not add any plugging by
> +	 * quiescing so it is safe to sync queue now.
> +	 */
> +	blk_sync_queue(nullb->q);
> +	blk_mq_tagset_busy_iter(nullb->tag_set, null_cancel_request, nullb);
> +	blk_mq_tagset_wait_completed_request(nullb->tag_set);
> +	/*
> +	 * Unblock any pending dispatch I/Os before we destroy the device.
> +	 * From null_destroy_dev()->del_gendisk() will set GD_DEAD flag
> +	 * causing any new I/O from __bio_queue_enter() to fail with -ENODEV.
> +	 */
> +	blk_mq_unquiesce_queue(nullb->q);
> +
> +	null_destroy_dev(nullb);

destroying device is never good cleanup for handling timeout/abort, and it
should have been the last straw any time.


thanks, 
Ming