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From: David Hildenbrand <david@redhat.com>
To: Muchun Song <songmuchun@bytedance.com>, akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH v2] mm/page_isolation: do not isolate the max order page
Date: Thu, 3 Dec 2020 17:28:00 +0100	[thread overview]
Message-ID: <46fcf0c1-7c38-723b-8905-953d72f1d6bc@redhat.com> (raw)
In-Reply-To: <20201203162237.21885-1-songmuchun@bytedance.com>

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
description can be simplified - e.g., stating that we have/had not such
users.


-- 
Thanks,

David / dhildenb



  reply	other threads:[~2020-12-03 16:28 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 [this message]
2020-12-04 16:12   ` [External] " Muchun Song
2020-12-04 17:12     ` David Hildenbrand
2020-12-07 13:42 ` Oscar Salvador

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