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To: Zi Yan , David Hildenbrand , linux-mm@kvack.org Cc: Matthew Wilcox , "Kirill A . Shutemov" , Mike Kravetz , Michal Hocko , John Hubbard , linux-kernel@vger.kernel.org, Mike Rapoport References: <20210805190253.2795604-1-zi.yan@sent.com> From: Vlastimil Babka Message-ID: <40982106-0eee-4e62-7ce0-c4787b0afac4@suse.cz> Date: Fri, 6 Aug 2021 17:36:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210805190253.2795604-1-zi.yan@sent.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: B0C3C5003D62 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=YwLLjMqA; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=te7htrDx; dmarc=none; spf=pass (imf04.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Stat-Signature: sbbksxfids4pjdn49bxweo6iip1xnxue X-HE-Tag: 1628264180-430409 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 8/5/21 9:02 PM, Zi Yan wrote: > From: Zi Yan > Patch 3 restores the pfn_valid_within() check when buddy allocator can merge > pages across memory sections. The check was removed when ARM64 gets rid of holes > in zones, but holes can appear in zones again after this patchset. To me that's most unwelcome resurrection. I kinda missed it was going away and now I can't even rejoice? I assume the systems that will be bumping max_order have a lot of memory. Are they going to have many holes? What if we just sacrificed the memory that would have a hole and don't add it to buddy at all?