Re: [PATCH mm-unstable v2 3/5] mm/khugepaged: define COLLAPSE_MAX_PTES_LIMIT as HPAGE_PMD_NR - 1

[David Hildenbrand (Arm)]

On 2/26/26 21:17, Nico Pache wrote:
> On Thu, Feb 26, 2026 at 2:28 AM David Hildenbrand (Arm)
> <david@xxxxxxxxxx> wrote:
>>
>> On 2/26/26 02:29, Nico Pache wrote:
>>> The value (HPAGE_PMD_NR - 1) is used often in the khugepaged code to
>>> signify the limit of the max_ptes_* values. Add a define for this to
>>> increase code readability and reuse.
>>>
>>> Acked-by: Pedro Falcato <pfalcato@xxxxxxx>
>>> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
>>> Signed-off-by: Nico Pache <npache@xxxxxxxxxx>
>>> ---
>>>  mm/khugepaged.c | 9 +++++----
>>>  1 file changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
>>> index 2ef4b972470b..4615f34911d1 100644
>>> --- a/mm/khugepaged.c
>>> +++ b/mm/khugepaged.c
>>> @@ -89,6 +89,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
>>>   *
>>>   * Note that these are only respected if collapse was initiated by khugepaged.
>>>   */
>>> +#define COLLAPSE_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1)
>>
>> I'd call it "KHUGEPAGED_MAX_PTES_LIMIT", because it's khugepaged
>> specific (no madvise) and matches the parameters.
> 
> Ok before changing that, note that this is also leveraged in the mTHP
> set. It's technically used for madvise collapse because when it's not
> khugepaged we set max_ptes_none= 511.

It's more about disabling that parameter, right?

-- 
Cheers,

David