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[209.85.167.51]) by smtp.gmail.com with ESMTPSA id p15sm1151988lja.116.2021.02.25.09.54.50 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Feb 2021 09:54:50 -0800 (PST) Received: by mail-lf1-f51.google.com with SMTP id d24so9848733lfs.8 for ; Thu, 25 Feb 2021 09:54:50 -0800 (PST) X-Received: by 2002:a05:6512:398d:: with SMTP id j13mr2392819lfu.41.1614275689864; Thu, 25 Feb 2021 09:54:49 -0800 (PST) MIME-Version: 1.0 References: <20210224153950.20789-1-rppt@kernel.org> <20210224153950.20789-2-rppt@kernel.org> <515b4abf-ff07-a43a-ac2e-132c33681886@redhat.com> <20210225170629.GE1854360@linux.ibm.com> In-Reply-To: <20210225170629.GE1854360@linux.ibm.com> From: Linus Torvalds Date: Thu, 25 Feb 2021 09:54:34 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v7 1/1] mm/page_alloc.c: refactor initialization of struct page for holes in memory layout To: Mike Rapoport Cc: David Hildenbrand , Mike Rapoport , Andrew Morton , Andrea Arcangeli , Baoquan He , Borislav Petkov , Chris Wilson , "H. Peter Anvin" , Ingo Molnar , =?UTF-8?Q?=C5=81ukasz_Majczak?= , Mel Gorman , Michal Hocko , Qian Cai , "Sarvela, Tomi P" , Thomas Gleixner , Vlastimil Babka , Linux Kernel Mailing List , Linux-MM , stable , "the arch/x86 maintainers" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 048EC130 X-Stat-Signature: p8g9jhjpy68zgacqoxk3kp5tbszntft3 Received-SPF: none (linuxfoundation.org>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=mail-lj1-f179.google.com; client-ip=209.85.208.179 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614275693-683962 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 Thu, Feb 25, 2021 at 9:07 AM Mike Rapoport wrote: > > > > > We might still double-initialize PFNs when two zones overlap within a > > section, correct? > > You mean that a section crosses zones boundary? > I don't think it's that important. What if there was a memory allocation in between that could allocate the once-initialized page? Maybe it can't happen, or is not an issue for some other reason, but this code has been fragile and had a ton of subtle issues, so maybe worth documenting (or explaining here why it's just not relevant) Linus