Re: [PATCH v4 0/4] Make MIGRATE_ISOLATE a standalone bit

[David Hildenbrand <david@redhat.com>]

On 20.05.25 15:31, Zi Yan wrote:
> On 20 May 2025, at 9:20, David Hildenbrand wrote:
> 
>>>> if a page gets freed while the pageblock is isolated, it cannot get added to the list of an owner easily.
>>>
>>> Right. In theory, it is possible, since when a MIGRATED_ISOLATE page is freed,
>>> __free_one_page() can find its buddy and add the freed page to its buddy's
>>> buddy_list without performing a merge like current code. But it needs a new
>>> code path in __add_to_free_list(), since it is not added to the head nor the
>>> tail of a free list.
>>
>> But what if the whole pageblock gets freed in a single shot (IOW, there is no buddy to lookup the list for?).
> 

And thinking about it, another problem is if a page gets freed that has 
no buddies.

> You are right. This means when MIGRATE_ISOLATE is removed, the global
> MIGRATE_ISOLATE free list stays.

Right. We could just have that one separately from the existing array.

-- 
Cheers,

David / dhildenb