[Crash-utility] [PATCH v4] arm64/x86_64: show zero pfn information when using vtop

[lijiang]

On Mon, May 29, 2023 at 7:56 PM Rongwei Wang <rongwei.wang at linux.alibaba.com>
wrote:

> Now vtop can not show us the page is zero pfn
> when PTE or PMD has attached ZERO PAGE. This
> patch supports show this information directly
> when using vtop, likes:
>
> crash> vtop -c 13674 ffff8917e000
> VIRTUAL     PHYSICAL
> ffff8917e000  836e71000
>
> PAGE DIRECTORY: ffff000802f8d000
>    PGD: ffff000802f8dff8 => 884e29003
>    PUD: ffff000844e29ff0 => 884e93003
>    PMD: ffff000844e93240 => 840413003
>    PTE: ffff000800413bf0 => 160000836e71fc3
>   PAGE: 836e71000  (ZERO PAGE)
> ...
>
> If huge page found:
>
> crash> vtop -c 14538 ffff95800000
> VIRTUAL     PHYSICAL
> ffff95800000  910c00000
>
> PAGE DIRECTORY: ffff000801fa0000
>    PGD: ffff000801fa0ff8 => 884f53003
>    PUD: ffff000844f53ff0 => 8426cb003
>    PMD: ffff0008026cb560 => 60000910c00fc1
>   PAGE: 910c00000  (2MB, ZERO PAGE)
> ...
>
> That seems be sensible with this patch. And there
> are two points have to be noted for 'ZERO PAGE'
> label:
> 1. only supports displaying zero page for THP(except for 1G THP)
> 2. do not support for the hugetlb cases
>
> Thank you for the update, Rongwei.

I have no other issues. So, for the v4: Ack.

Thanks.
Lianbo
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