mmc: block: bonnie++ runs with errors on arc/hsdk board

[Adrian Hunter]

On 13/03/18 14:04, Evgeniy Didin wrote:
> Hello Adrian,
> 
> I have discovered, that beggining with 4.16-rc1 bonnie++ benchmark
> runs with errors on arc/hsdk board. After bisecting between 4.15 and 4.16-rc1,
> I have found that errors started after 
> commit 81196976ed94 (mmc: block: Add blk-mq support).
> 
> Error message is like:
> 
> | # bonnie++ -u root -r 256 -s 512 -x 1 -d  /mnt 
> | Using uid:0, gid:0.
> | Writing with putc()...random: crng init done
> | done
> | Writing intelligently...INFO: task kworker/u8:0:5 blocked for more than 10 seconds.
> |      Not tainted 4.15.0-rc3-00012-g81196976ed94-dirty #1
> | "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> | kworker/u8:0    D    0     5      2 0x00000000
> | Workqueue: writeback wb_workfn (flush-179:0)
> |
> | Stack Trace:
> |  __switch_to+0x0/0xac
> |  __schedule+0x1b8/0x738
> |  io_schedule+0x5c/0xc0
> |  bit_wait_io+0xc/0x48
> |  out_of_line_wait_on_bit+0x78/0xc0
> |  do_get_write_access+0x1aa/0x4cc
> |  jbd2_journal_get_write_access+0x32/0x74
> |  __ext4_journal_get_write_access+0x3a/0xac
> |  ext4_mb_mark_diskspace_used+0x66/0x5b0
> |  ext4_mb_new_blocks+0x1ee/0x830
> |  ext4_ext_map_blocks+0x504/0xcac
> |  ext4_map_blocks+0x262/0x5e8
> |  mpage_map_and_submit_extent+0xb8/0x648
> |  ext4_writepages+0x5ce/0x6b4
> |  do_writepages+0x20/0x84
> |  __writeback_single_inode+0x2a/0x154
> |  wb_writeback+0x538/0xae0
> |  wb_workfn+0x17c/0x334
> |  process_one_work+0x1a6/0x350
> |  worker_thread+0xf2/0x478
> |  kthread+0x120/0x13c
> |  ret_from_fork+0x18/0x1c
> 
> There are some details of hsdk_defconfig presented bellow:
> 
> SOFTLOCKUP_DETECTOR=y
> DETECT_HUNG_TASK=y
> DEFAULT_HUNG_TASK_TIMEOUT=10
> MMC_DW=y
> MMC_DW_PLTFM=y
> 
> I have also tested bonnie++ on Wandboard on v4.16-rc5 with the same
> DEFAULT_HUNG_TASK_TIMEOUT=10, but there were no errors.
> 
> Even though it is not critical error and we see bonnie++ test proceeds to the end,
> still it is strange, that some process is running in kernel space for a long time (at least 10sec).
> What is strange, before metioned commit I can't reproduce this behaviour.
> 
> I am wondering is this expected behaviour? 

Was the performance affected? i.e. the results from bonnie++

What mount options did you use?