Re: [v2 00/16] mm: PMD-level swap entries for anonymous THPs

Re: [v2 00/16] mm: PMD-level swap entries for anonymous THPs

[Usama Arif]

On 02/06/2026 15:24, Usama Arif wrote:
> When reclaim swaps out a PMD-mapped anonymous THP today, the PMD is
> split into 512 PTE-level swap entries via TTU_SPLIT_HUGE_PMD before
> unmap.
> 
> This series introduces a PMD-level swap entry. The huge mapping is
> preserved across the swap round-trip, and do_huge_pmd_swap_page()
> resolves the entire 2 MB region in a single fault on swap-in,
> no khugepaged involvement is needed. swap_map metadata is identical
> either way (512 single-slot counts), so the PTE split buys nothing
> on the swap side, it is purely a page-table representation change.
> 

Hello!

Just following up if there were any reviews/comments on this series!

I know its a large series but was just checking if there was any
feedback?

Thanks!
Usama

Re: [v2 00/16] mm: PMD-level swap entries for anonymous THPs

[David Hildenbrand (Arm)]

On 6/9/26 16:29, Usama Arif wrote:
> 
> 
> On 02/06/2026 15:24, Usama Arif wrote:
>> When reclaim swaps out a PMD-mapped anonymous THP today, the PMD is
>> split into 512 PTE-level swap entries via TTU_SPLIT_HUGE_PMD before
>> unmap.
>>
>> This series introduces a PMD-level swap entry. The huge mapping is
>> preserved across the swap round-trip, and do_huge_pmd_swap_page()
>> resolves the entire 2 MB region in a single fault on swap-in,
>> no khugepaged involvement is needed. swap_map metadata is identical
>> either way (512 single-slot counts), so the PTE split buys nothing
>> on the swap side, it is purely a page-table representation change.
>>
> 
> Hello!
> 
> Just following up if there were any reviews/comments on this series!
> 
> I know its a large series but was just checking if there was any
> feedback?

It shall be reviewed. We just finished the mTHP khugepaged review to get it into
7.2, so we've all been rather busy.

(I mean, just take a look at the THP-related flood of patches we are fighting
with on a daily basis, it's not funny anymore)

This is clearly going to be 7.3 material, so there is plenty of time given that
the merge window is about to open soon.

-- 
Cheers,

David

Re: [v2 00/16] mm: PMD-level swap entries for anonymous THPs

[Lance Yang]

On 2026/6/10 20:24, David Hildenbrand (Arm) wrote:
> On 6/9/26 16:29, Usama Arif wrote:
>>
>>
>> On 02/06/2026 15:24, Usama Arif wrote:
>>> When reclaim swaps out a PMD-mapped anonymous THP today, the PMD is
>>> split into 512 PTE-level swap entries via TTU_SPLIT_HUGE_PMD before
>>> unmap.
>>>
>>> This series introduces a PMD-level swap entry. The huge mapping is
>>> preserved across the swap round-trip, and do_huge_pmd_swap_page()
>>> resolves the entire 2 MB region in a single fault on swap-in,
>>> no khugepaged involvement is needed. swap_map metadata is identical
>>> either way (512 single-slot counts), so the PTE split buys nothing
>>> on the swap side, it is purely a page-table representation change.
>>>
>>
>> Hello!
>>
>> Just following up if there were any reviews/comments on this series!
>>
>> I know its a large series but was just checking if there was any
>> feedback?
> 
> It shall be reviewed. We just finished the mTHP khugepaged review to get it into
> 7.2, so we've all been rather busy.

Right, mTHP khugepaged was a rough one. Glad we got it over the line,
but yeah, there's just been a lot of THP work lately. pretty nonstop ...

> (I mean, just take a look at the THP-related flood of patches we are fighting
> with on a daily basis, it's not funny anymore)
> 
> This is clearly going to be 7.3 material, so there is plenty of time given that
> the merge window is about to open soon.

Usama, I'll try to make this one a priority too. Looks interesting :P

Cheers, Lance

Re: [v2 00/16] mm: PMD-level swap entries for anonymous THPs

[David Hildenbrand (Arm)]

On 6/10/26 15:01, Lance Yang wrote:
> 
> 
> On 2026/6/10 20:24, David Hildenbrand (Arm) wrote:
>> On 6/9/26 16:29, Usama Arif wrote:
>>>
>>>
>>>
>>> Hello!
>>>
>>> Just following up if there were any reviews/comments on this series!
>>>
>>> I know its a large series but was just checking if there was any
>>> feedback?
>>
>> It shall be reviewed. We just finished the mTHP khugepaged review to get it into
>> 7.2, so we've all been rather busy.
> 
> Right, mTHP khugepaged was a rough one. Glad we got it over the line,
> but yeah, there's just been a lot of THP work lately. pretty nonstop ...
> 
>> (I mean, just take a look at the THP-related flood of patches we are fighting
>> with on a daily basis, it's not funny anymore)
>>
>> This is clearly going to be 7.3 material, so there is plenty of time given that
>> the merge window is about to open soon.
> 
> Usama, I'll try to make this one a priority too. Looks interesting :P

I have two other bigger series to review, but I should soon get to this as well.

-- 
Cheers,

David

Re: [v2 00/16] mm: PMD-level swap entries for anonymous THPs

[Usama Arif]

On 10/06/2026 14:48, David Hildenbrand (Arm) wrote:
> On 6/10/26 15:01, Lance Yang wrote:
>>
>>
>> On 2026/6/10 20:24, David Hildenbrand (Arm) wrote:
>>> On 6/9/26 16:29, Usama Arif wrote:
>>>>
>>>>
>>>>
>>>> Hello!
>>>>
>>>> Just following up if there were any reviews/comments on this series!
>>>>
>>>> I know its a large series but was just checking if there was any
>>>> feedback?
>>>
>>> It shall be reviewed. We just finished the mTHP khugepaged review to get it into
>>> 7.2, so we've all been rather busy.
>>
>> Right, mTHP khugepaged was a rough one. Glad we got it over the line,
>> but yeah, there's just been a lot of THP work lately. pretty nonstop ...
>>

Yeah its definitely a lot. I have set a target of leaving review comments on
atleast 2 patches from mm per day myself, but even that can sometimes be
difficult! I will try and help out more in reviews.

>>> (I mean, just take a look at the THP-related flood of patches we are fighting
>>> with on a daily basis, it's not funny anymore)
>>>
>>> This is clearly going to be 7.3 material, so there is plenty of time given that
>>> the merge window is about to open soon.
>>
>> Usama, I'll try to make this one a priority too. Looks interesting :P

Thanks Lance!

> 
> I have two other bigger series to review, but I should soon get to this as well.
> 

No worries at all! Thanks for the reviews! and yeah definitely 7.3.

I will send this out again when 7.3-rc1 opens (rebased), so that the reviews wont be on
outdated code which could cause some confusion.