Re: [PATCH v5 0/9] mm/memory-failure: keep hardware-poisoned pages out of the next kexec

[Miaohe Lin]

On 2026/9/22 17:14, Breno Leitao wrote:
> Hello Miaohe,
> 
> On Tue, Sep 22, 2026 at 02:27:59PM +0800, Miaohe Lin wrote:
>>> A bit is never cleared, which is a known limitation: it stands for a
>>> whole unit, so an unpoison of one frame cannot tell whether the unit as a
>>> whole is good again.
>>
>> Thanks for your patches. I have a question about unpoison: If a bit is never
>> cleared, after we do some memory-failure+unpoison tests, kexec will lose the
>> tested memory without reboot?
> 
> Correct, A bit stands for a 2M unit, so every tested page that falls in
> a distinct unit costs 2M in each kernel after the kexec.
> 
> Worth being precise about the state today: the unpoison itself works.
> The frame goes back to the allocator and num_poisoned_pages drops. Only
> the bit stays, so the next kernel poisons the frame again. Test loop
> in, memory out, and nothing gives it back.
> 
> Important to say that nothing block us from unpoison the bitmap, and in
> fact my initial patchset had it. I also _think_ we should unpoison the
> bitmap once we unpoison the page. 
> 
> I have just kept it out of this patch in order to simplify the patchset and
> get the basis correct, and then evolve on top of it.
> 

Makes sense to me. Thanks for your work.

> That said, If you think this is a must have in first patchset, I am more
> than happy to do it now, but just keep it in mind that it will grow the
> patchset by about 2 extra functions.
> 
> Thanks the review,
> --breno
> .
>