Re: [RFC PATCH] mm/mglru: fix ineffective memory protection for non-kswapd reclaim

[Ridong Chen <ridong.chen@linux.dev>]

On 8/27/2026 5:26 PM, Michal Koutný wrote:
> Hi Ridong.
> 
> On Thu, Aug 27, 2026 at 09:29:13AM +0800, Ridong Chen <ridong.chen@linux.dev> wrote:
>> On 8/26/2026 9:47 PM, sashiko-bot@kernel.org wrote:
>>> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
>>>
>>> Pre-existing issues:
>>> - [High] Integer overflow in `effective_protection()` calculations on systems with >= 16TB RAM.
>>> --
>>>
>>
>> Thanks for the careful analysis. You're right that this is pre-existing in
>> effective_protection() and not introduced by this patch.
>>
>> I'm not sure it's worth fixing in practice, though — the overflow requires
>> systems with >= 16TB of RAM, which I've never encountered
>> myself. So I'd rather not fold a fix for it into this patch.
>>
>> I'd like to hear the maintainers' thoughts on whether this is worth
>> addressing separately.
> 
> Machines with >=16 TiB aren't completely out of reach [1]. Then
> configuring such protections to attain the overflow is another
> condition, so I'd consider this a nice to have but not a
> pressing fixup (separately, with thorough review of occurences where
> total page counts/bytes might get multiplied).
> 
> HTH,
> Michal
> 
> [1] E.g. https://aws.amazon.com/ec2/instance-types/u7i/

Thanks Michal,

It's worth fixing now, I'll send a separate patch to address it.

-- 
Best regards
Ridong