On Mon, Feb 12, 2018 at 10:41:05AM +0100, Matthias Ferdinand wrote:

On Mon, Feb 12, 2018 at 04:57:52PM +0800, tang.junhui@zte.com.cn wrote:

quoted

From: Tang Junhui <redacted>


Hello Matthias,

What kind of caching mode do you use? Writeback or Writethrough?

Hi, thanks for looking into this.

This is with writeback caching (haven't tried writethrough yet).

Some more info about the disk drives used:

# ls -l /dev/disk/by-id  | grep -v -- -part | grep -v wwn-
total 0
lrwxrwxrwx 1 root root  9 Feb  8 00:48 ata-INTEL_SSDSC2BA200G4_BTHV7374017P200MGN -> ../../sdf
lrwxrwxrwx 1 root root  9 Feb  8 00:48 ata-WDC_WD2005FBYZ-01YCBB2_WD-WMC6N0K0SHRT -> ../../sdc
lrwxrwxrwx 1 root root  9 Feb  8 00:48 ata-WDC_WD2005FBYZ-01YCBB2_WD-WMC6N0K2KNK4 -> ../../sda
lrwxrwxrwx 1 root root  9 Feb  8 00:48 ata-WDC_WD2005FBYZ-01YCBB2_WD-WMC6N0K5KHNS -> ../../sdb
lrwxrwxrwx 1 root root  9 Feb  8 00:48 ata-WDC_WD2005FBYZ-01YCBB2_WD-WMC6N0K7212Z -> ../../sde
lrwxrwxrwx 1 root root  9 Feb  8 00:48 usb-Samsung_Flash_Drive_0352315110002396-0:0 -> ../../sdd

More de-obfuscation:
   - Intel SSD DC S3710 SATA 200GB for caching
   - WD Gold SATA 2TB for backing device

I now also tested with alternatives writethrough and with "hdparm -W 1",
they also crash.

Perhaps more relevant: fio is started immediately after setup of md
raid and bcache, while md sync speed is set very low:

    echo "1" >/sys/block/md127/md/sync_speed_min
    echo "1" >/sys/block/md127/md/sync_speed_max


I attached the script I use for producing the crashes, hope this helps.

Regards
Matthias Ferdinand