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b=ZPQxDQ2PwLXpWqinMgBQRN97ZkH0MQvovaLYeB4w1HxqXKfBITyukOtR5Xeh5LdEG YwhgvHjqCW3tRJlrBa+d6p9p/oIr6QBMEY0T32z1OQtcqRIVP2oVnf8jAKzaLI6x4p PEZbiQJO0vA8Xzad3bEqwkDQsjyVs7nj2fwqc53z32HUG6UIeV7UfaRZbde0jTR5LQ XwqKUqwZkzLSQCgA9+E7jQyTi1MVSEgZhvhsNPhKInezo6YkvmMnrUgVkkLorfp7b9 6CO1kMKHWltCupII9JDmmCz/JMmriijlTQY2+euPnxiu0X5iDoWDR7wFXUKxerljuf KcvLNPfoOvCzQ== Date: Thu, 5 Oct 2023 08:06:19 +0300 From: Mike Rapoport To: Yajun Deng Cc: David Hildenbrand , 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 Message-ID: <20231005050619.GB3303@kernel.org> References: <20230929100252.GW3303@kernel.org> <15233624-f32e-172e-b2f6-7ca7bffbc96d@linux.dev> <20231001185934.GX3303@kernel.org> <90342474-432a-9fe3-2f11-915a04f0053f@linux.dev> <20231002084708.GZ3303@kernel.org> <20231002111051.GA3303@kernel.org> <3057dab3-19f2-99ca-f125-e91a094975ed@redhat.com> <8c9ee3bd-6d71-4111-8f4e-91bc52b42ed4@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8c9ee3bd-6d71-4111-8f4e-91bc52b42ed4@linux.dev> X-Rspamd-Queue-Id: 3709820014 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: rqzdrbop9581zdoo9ge8zxcnf7jtbdqn X-HE-Tag: 1696482446-213162 X-HE-Meta: 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 EbQ+BGT1 UQHah/V7kB50bzFZtT2hGgixGkz1RF2JK9qGfpOcC0cnNnM33Uu8ZJ67GjGGAn0x2UZht5KwE343s0svIUT5AqFlhdUd/Ri27WvwfJZ4VntV6ouCCJFhWoX39QawZivZpfFw0ZdO6gcH9Q+z4NiSnPmVK/ptbpXsL2jZXXBxB6VAZqzFPnSlE/WHaowOCeNFv/ucGvQ2qXen6COPZfWNJC0UZxdfiuPfU+0e7JgWtGh5w5KN1uUMbFXqznw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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? -- Sincerely yours, Mike.