Re: [External] Re: [PATCH v2] mm/page_isolation: do not isolate the max order page

[David Hildenbrand]

On 04.12.20 17:12, Muchun Song wrote:
> On Fri, Dec 4, 2020 at 12:28 AM David Hildenbrand <david@xxxxxxxxxx> wrote:
>>
>> On 03.12.20 17:22, Muchun Song wrote:
>>> The max order page has no buddy page and never merge to other order.
>>> So isolating and then freeing it is pointless. And if order == MAX_ORDER
>>> - 1, then the buddy can actually be a !pfn_valid() in some corner case?
>>> pfn_valid_within(buddy_pfn) that follows would only catch it on archs
>>> with holes in zone. Then is_migrate_isolate_page(buddy) might access an
>>> invalid buddy. So this is also a bug fix.
>>>
>>> Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
>>
>> As just replied to v1, I don't think this is required and the patch
> 
> You mean we should remove the Fixes tag? Thanks.

As discussed in v1, I don't think we really have systems where this
applies, but could be in corner cases on MIPS or with FLATMEM. Let's
just leave it like that. :)

Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

-- 
Thanks,

David / dhildenb