On Fri, May 3, 2019 at 6:15 PM Bart Van Assche <bvanassche@xxxxxxx> wrote: > > On 5/3/19 10:47 AM, Evan Green wrote: > > Hey blockies, > ^^^^^^^^^^^^ > > That's the weirdest greeting I have encountered so far on the > linux-block mailing list. Heh, achievement unlocked. > > > I'm seeing a hung task in the kernel, and I wanted to share it in case > > it's a known issue. I'm still trying to wrap my head around the stacks > > myself. This is our Chrome OS 4.19 kernel, which is admittedly not > > 100% vanilla mainline master, but we try to keep it pretty close. > > > > I can reproduce this reliably within our chrome OS installer, where > > it's trying to dd from my system disk (NVMe) to a loop device backed > > by a removable UFS card (4kb sectors) in a USB dongle. > > Although this is not the only possible cause such hangs are often caused > by a block driver or SCSI LLD not completing a request. A list of > pending requests can be obtained e.g. by running the attached script. Thanks for the script. I'll try a few different combinations of dd involving the UFS card to see if I can at least remove the system disk from the equation. Hopefully the system will still be responsive enough to run the script if I keep it in the right place and maybe pre-warm it up. I also might try an older kernel, since if it's a misbehaving block device as you suggest then all kernel versions should lock up. > > Bart.
