From: Yajun Deng <yajun.deng@linux.dev>
To: Mike Rapoport <rppt@kernel.org>
Cc: David Hildenbrand <david@redhat.com>,
akpm@linux-foundation.org, mike.kravetz@oracle.com,
muchun.song@linux.dev, willy@infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY
Date: Thu, 5 Oct 2023 22:04:28 +0800 [thread overview]
Message-ID: <6545ac4c-1205-6c09-49ea-e00c24d1a2ff@linux.dev> (raw)
In-Reply-To: <20231005050619.GB3303@kernel.org>
On 2023/10/5 13:06, Mike Rapoport wrote:
> On Tue, Oct 03, 2023 at 10:38:09PM +0800, Yajun Deng wrote:
>> On 2023/10/2 19:25, David Hildenbrand wrote:
>>> On 02.10.23 13:10, Mike Rapoport wrote:
>>>>>> That 'if' breaks the invariant that __free_pages_core is
>>>>>> always called for
>>>>>> pages with initialized page count. Adding it may lead to
>>>>>> subtle bugs and
>>>>>> random memory corruption so we don't want to add it at the
>>>>>> first place.
>>>>> As long as we have to special-case memory hotplug, we know that we are
>>>>> always coming via generic_online_page() in that case. We could
>>>>> either move
>>>>> some logic over there, or let __free_pages_core() know what it
>>>>> should do.
>>>> Looks like the patch rather special cases MEMINIT_EARLY, although I
>>>> didn't
>>>> check throughfully other code paths.
>>>> Anyway, relying on page_count() to be correct in different ways for
>>>> different callers of __free_pages_core() does not sound right to me.
>>> Absolutely agreed.
>>>
>> I already sent v5 a few days ago. Comments, please...
> Does it address all the feedback from this thread?
>
Except hotplug. As far as I konw, we only clear page count in
MEMINIT_EARLY and all tail pages in compound page.
So adding 'if (page_count(page))' will have no actual effect for other
case. According to previous data, it didn't
become slower in hotplug.
next prev parent reply other threads:[~2023-10-05 14:06 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-28 8:33 [PATCH v4 0/2] mm: Don't set and reset page count in MEMINIT_EARLY Yajun Deng
2023-09-28 8:33 ` [PATCH v4 1/2] mm: pass page count and reserved to __init_single_page Yajun Deng
2023-09-29 8:19 ` Mike Rapoport
2023-09-29 9:37 ` Yajun Deng
2023-09-28 8:33 ` [PATCH v4 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY Yajun Deng
2023-09-29 8:30 ` Mike Rapoport
2023-09-29 9:50 ` Yajun Deng
2023-09-29 10:02 ` Mike Rapoport
2023-09-29 10:27 ` Yajun Deng
2023-10-01 18:59 ` Mike Rapoport
2023-10-02 7:03 ` Yajun Deng
2023-10-02 8:47 ` Mike Rapoport
2023-10-02 8:56 ` David Hildenbrand
2023-10-02 11:10 ` Mike Rapoport
2023-10-02 11:25 ` David Hildenbrand
2023-10-03 14:38 ` Yajun Deng
2023-10-05 5:06 ` Mike Rapoport
2023-10-05 14:04 ` Yajun Deng [this message]
2023-10-12 9:19 ` Mike Rapoport
2023-10-12 9:36 ` Yajun Deng
2023-10-02 8:30 ` David Hildenbrand
2023-10-08 8:57 ` Yajun Deng
2023-10-10 2:31 ` Yajun Deng
2023-10-12 9:23 ` David Hildenbrand
2023-10-12 9:53 ` Yajun Deng
2023-10-13 8:48 ` Mike Rapoport
2023-10-13 9:29 ` Yajun Deng
2023-10-16 6:33 ` Mike Rapoport
2023-10-16 8:10 ` Yajun Deng
2023-10-16 8:16 ` David Hildenbrand
2023-10-16 8:32 ` Yajun Deng
2023-10-16 8:36 ` David Hildenbrand
2023-10-16 10:17 ` Yajun Deng
2023-10-17 9:58 ` Yajun Deng
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