Re: [PATCH 0/7] enable PT_RECLAIM on all 64-bit architectures

David Hildenbrand (Red Hat)
2025-11-19T10:13:46Z

On 18.11.25 12:53, Qi Zheng wrote:
>
>
> On 11/18/25 12:53 AM, David Hildenbrand (Red Hat) wrote:
>> On 14.11.25 12:11, Qi Zheng wrote:
>>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>>
>>> Hi all,
>>>
>>> This series aims to enable PT_RECLAIM on all 64-bit architectures.
>>>
>>> On a 64-bit system, madvise(MADV_DONTNEED) may cause a large number of
>>> empty PTE
>>> page table pages (such as 100GB+). To resolve this problem, we need to
>>> enable
>>> PT_RECLAIM, which depends on MMU_GATHER_RCU_TABLE_FREE.
>>>
>>
>> Makes sense!
>>
>>> Therefore, this series first enables MMU_GATHER_RCU_TABLE_FREE on all
>>> 64-bit
>>> architectures, and finally makes PT_RECLAIM depend on
>>> MMU_GATHER_RCU_TABLE_FREE
>>> && 64BIT. This way, PT_RECLAIM can be enabled by default on all 64-bit
>>> architectures.
>>
>> Could we then even go ahead and stop making PT_RECLAIM user-selectable?
>
> OK, will change to:

Was more of a question: is there any scenario where we ran so far into
issues with it?

--
Cheers

David