# Re: \[External\] \[PATCH v3 01/14\] memory-failure: fetch compound\_head after pgmap\_pfn\_valid()

- From: Muchun Song \<hidden\>
- Date: 2021-07-15 02:52:26 
- List: linux-doc
- Page: https://ratatoskr.run/linux-doc/2021/07/6509839
- Thread: https://ratatoskr.run/linux-mm/2021/07/6509813/t.md

```text
On Thu, Jul 15, 2021 at 3:36 AM Joao Martins [ref] wrote:
>
> memory_failure_dev_pagemap() at the moment assumes base pages (e.g.
> dax_lock_page()).  For pagemap with compound pages fetch the
> compound_head in case a tail page memory failure is being handled.
>
> Currently this is a nop, but in the advent of compound pages in
> dev_pagemap it allows memory_failure_dev_pagemap() to keep working.
>
> Reported-by: Jane Chu <redacted>
> Signed-off-by: Joao Martins <redacted>
> Reviewed-by: Naoya Horiguchi <redacted>

Reviewed-by: Muchun Song <redacted>
```