> This depends on kernel version number, it might be more friendly for the
> distribution to output some debug info as below:
>
> if (CRASHDEBUG(1))
>      error(INFO, "ZRAM_FLAG_SHIFT=%lu\n", ZRAM_FLAG_SHIFT);
>
> Once the related kernel patches are backported to an old kernel, the
> similar checking may fail. But, at least we can know a little more with the
> crash debug info.

Sounds good, then I would like to show the shift value instead of mask
value, so changed a little.  Is the attached patch OK?

6.1:
   crash> rd 7fb60bdff000
   zram_flag_shift: 13
   ...

RHEL8:
   crash> rd 7ff668048000
   zram_flag_shift: 24

4.18 and later kernels has ZRAM_LOCK, so I think usually the else-if
block isn't used and it's kind of a fail-safe for a future change.

Anyway, thank you for the good comments.

Thanks,
Kazu