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From: David Hildenbrand <david@redhat.com>
To: Muchun Song <songmuchun@bytedance.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [External] Re: [PATCH v2] mm/page_isolation: do not isolate the max order page
Date: Fri, 4 Dec 2020 18:12:55 +0100	[thread overview]
Message-ID: <49b09de4-4b21-e6a7-0730-e125fcb398b3@redhat.com> (raw)
In-Reply-To: <CAMZfGtVdFtLB8f2uDfJ1H-YG4CsJ+RxxFbAWzePDnqBB1MU0ig@mail.gmail.com>

On 04.12.20 17:12, Muchun Song wrote:
> On Fri, Dec 4, 2020 at 12:28 AM David Hildenbrand <david@redhat.com> 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@redhat.com>

-- 
Thanks,

David / dhildenb


  reply	other threads:[~2020-12-04 17:14 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-03 16:22 [PATCH v2] mm/page_isolation: do not isolate the max order page Muchun Song
2020-12-03 16:28 ` David Hildenbrand
2020-12-04 16:12   ` [External] " Muchun Song
2020-12-04 17:12     ` David Hildenbrand [this message]
2020-12-07 13:42 ` Oscar Salvador

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