Re: [PATCH v3 03/12] mm/huge_memory: move THP gfp limit helper into header

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 4/22/26 1:23 AM, Zi Yan wrote:
> On 21 Apr 2026, at 13:21, Kairui Song wrote:
> 
>> On Tue, Apr 21, 2026 at 9:14 PM Zi Yan <ziy@nvidia.com> wrote:
>>>
>>> On 21 Apr 2026, at 2:16, Kairui Song via B4 Relay wrote:
>>>
>>>> From: Kairui Song <kasong@tencent.com>
>>>>
>>>> Shmem has some special requirements for THP GFP and has to limit it in
>>>> certain zones or provide a more lenient fallback.
>>>>
>>>> We'll use this helper for generic swap THP allocation, which needs to
>>>> support shmem. For a typical GFP_HIGHUSER_MOVABLE swap-in, this helper
>>>> is basically a no-op. But it's necessary for certain shmem users, mostly
>>>> drivers.
>>>>
>>>> No feature change.
>>>>
>>>> Signed-off-by: Kairui Song <kasong@tencent.com>
>>>> ---
>>>>   include/linux/huge_mm.h | 30 ++++++++++++++++++++++++++++++
>>>>   mm/shmem.c              | 30 +++---------------------------
>>>>   2 files changed, 33 insertions(+), 27 deletions(-)
>>>>
>>>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
>>>> index 2949e5acff35..ffe5a120eee4 100644
>>>> --- a/include/linux/huge_mm.h
>>>> +++ b/include/linux/huge_mm.h
>>>> @@ -237,6 +237,31 @@ static inline bool thp_vma_suitable_order(struct vm_area_struct *vma,
>>>>        return true;
>>>>   }
>>>>
>>>> +/*
>>>> + * Make sure huge_gfp is always more limited than limit_gfp.
>>>> + * Some shmem users want THP allocation to be done less aggressively
>>>> + * and only in certain zone.
>>>> + */
>>>> +static inline gfp_t thp_limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
>>>
>>> Would it be better to rename it to thp_swap_limit_gfp_mask() or something
>>> more descriptive? I am just worried about misuses in the future due to
>>> the generic thp prefix.
>>
>> Good idea, I wasn't sure if this might be helpful for any other user,
>> but for now naming it more descriptive does help to avoid misuse.
>>
>> How about thp_shmem_limit_gfp_mask? Ordinary swap is fine with thp
>> gfp, only shmem is a bit special.
>>
> 
> Sounds good to me. Thanks.

Sounds good to me too. Feel free to add:
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>