From: David Hildenbrand <david@redhat.com>
To: Miaohe Lin <linmiaohe@huawei.com>, akpm@linux-foundation.org
Cc: mhocko@suse.com, vbabka@suse.cz, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/page_isolation: fix potential missing call to unset_migratetype_isolate()
Date: Mon, 6 Sep 2021 11:46:49 +0200 [thread overview]
Message-ID: <ec7fd827-55c8-120f-4c68-ec0076797d36@redhat.com> (raw)
In-Reply-To: <ebbef13c-921e-c385-1233-a7aeecec6127@huawei.com>
On 06.09.21 11:38, Miaohe Lin wrote:
> On 2021/9/6 17:27, David Hildenbrand wrote:
>> On 04.09.21 11:20, Miaohe Lin wrote:
>>> In start_isolate_page_range() undo path, pfn_to_online_page() just checks
>>> the first pfn in a pageblock while __first_valid_page() will traverse the
>>> pageblock until the first online pfn is found. So we may miss the call to
>>> unset_migratetype_isolate() in undo path and pages will remain isolated
>>> unexpectedly. Fix this by calling undo_isolate_page_range() and this will
>>> also help to remove some duplicated codes.
>>>
>>> Fixes: 2ce13640b3f4 ("mm: __first_valid_page skip over offline pages")
>>
>> While that is true, we shouldn't ever trigger, neither via cma, virtio-mem nor memory offlining, because essentially all operate on MAX_ORDER -1 -aligned ranges without memory holes.
>
> I think this should never trigger too. It's a theoretical issue. So is the Fixes tag necessary ?
>
I think it's one of these "let's add Fixes: but no need for Cc: stable".
BUT in older kernels we could have triggered this via memory offlining
eventually ... before c5e79ef561b0 ("mm/memory_hotplug.c: don't allow to
online/offline memory blocks with holes") ... so maybe even a Cc: stable?
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-09-06 9:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-04 9:20 [PATCH] mm/page_isolation: fix potential missing call to unset_migratetype_isolate() Miaohe Lin
2021-09-06 9:27 ` David Hildenbrand
2021-09-06 9:38 ` Miaohe Lin
2021-09-06 9:46 ` David Hildenbrand [this message]
2021-09-06 11:42 ` Miaohe Lin
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