# Re: \[PATCH v1 3/7\] mm: rename and move page\_is\_poisoned()

- From: David Hildenbrand \<hidden\>
- Date: 2021-05-05 13:39:15 
- List: virtualization
- Page: https://ratatoskr.run/virtualization/2021/05/205296
- Thread: https://ratatoskr.run/linux-hyperv/2021/04/204966/t.md

```text
>> Long story short, this should be good enough for the cases we actually can
>> handle? What am I missing?
>
> I am not sure I follow. My point is that I fail to see any added value
> of the check as it doesn't prevent the race (it fundamentally cannot as
> the page can be poisoned at any time) but the failure path doesn't
> put_page which is incorrect even for hwpoison pages.

Oh, I think you are right. If we have a page and return NULL we would leak a reference.

Actually, we discussed in that thread handling this entirely differently, which resulted in a v7 [1]; however Andrew moved forward with this (outdated?) patch, maybe that was just a mistake?

Yes, I agree we should revert that patch for now.

Regarding the race comment: AFAIU e.g., [2], it's not really a problem with a race, but rather some corner case issue that can happen if we fail in memory_failure().


[1] https://lkml.kernel.org/r/20210406104123.451ee3c3@alex-virtual-machine
[2] https://lkml.kernel.org/r/20210331015258.GB22060@hori.linux.bs1.fc.nec.co.jp

-- 
Thanks,

David / dhildenb

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