On Fri, 1 Mar 2019, Michael Holzheu wrote:
> Hi Mike,
>
> On Fedora 29, the following "linux-next" commit introduced a regression on s390:
>
> commit 1efa3bb79d3de8ca1b7f6770313a1fc0bebe25c7
> Author: Mike Snitzer <snitzer@xxxxxxxxxx>
> Date: Fri Feb 22 11:23:01 2019 -0500
>
> dm: must allocate dm_noclone for stacked noclone devices
>
> Otherwise various lvm2 testsuite tests fail because the lower layers of
> the stacked noclone device aren't updated to allocate a new 'struct
> dm_clone' that reflects the upper layer bio that was issued to it.
>
> Fixes: 97a89458020b38 ("dm: improve noclone bio support")
> Reported-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Should we just drop 97a89458020b388b910160c4f4aa5e24318d2460 and
1efa3bb79d3de8ca1b7f6770313a1fc0bebe25c7?
97a89458020b388b910160c4f4aa5e24318d2460 claims to be an improvement, but
it broke the tests twice.
Mikulas
> With this commit the boot hangs three minutes on a z/VM system with the
> following device mapper setup:
>
> # dmsetup ls --tree
> mpathe (252:5)
> ├─ (8:128)
> └─ (8:144)
> mpathd (252:4)
> ├─ (8:96)
> └─ (8:112)
> mpathc (252:3)
> ├─ (8:64)
> └─ (8:80)
> mpathb (252:2)
> ├─ (8:32)
> └─ (8:48)
> mpatha1 (252:1)
> └─mpatha (252:0)
> ├─ (8:16)
> └─ (8:0)
>
> On the console we get messages like the following:
>
> 10.116863 sd 3:0:0:1083719813: sdj Write Protect is off
> 10.117170 sd 3:0:0:1083719813: sdj Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
> 10.130562 sd 3:0:0:1083719813: sdj Attached SCSI disk
> A start job is running for udev Wai Device Initialization (6s / 3min)
> A start job is running for udev Wai Device Initialization (6s / 3min)
> A start job is running for udev Wai Device Initialization (7s / 3min)
> A start job is running for udev Wai Device Initialization (7s / 3min)
> A start job is running for udev Wai Device Initialization (8s / 3min)
> ...
>
> After three minutes the boot process continues and the system comes.
>
> As kernel config we used "performance_defconfig" (make performance_defconfig).
>
> Michael
>
