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[2003:cb:c704:b300:758c:6214:cd51:8ab0]) by smtp.gmail.com with ESMTPSA id e1-20020a05600c4e4100b003dc49e0132asm1535063wmq.1.2023.02.08.02.13.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Feb 2023 02:13:58 -0800 (PST) Message-ID: Date: Wed, 8 Feb 2023 11:13:57 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [RFC v3 2/4] mm: move PG_slab flag to page_type To: Mike Rapoport Cc: Matthew Wilcox , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Vlastimil Babka , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= , Joe Perches , Petr Mladek , Andy Shevchenko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alexander Potapenko , Marco Elver References: <20221218101901.373450-1-42.hyeyoo@gmail.com> <20221218101901.373450-3-42.hyeyoo@gmail.com> <15fda061-72d9-2ee9-0e9f-6f0f732a7382@suse.cz> <59630801-42b4-22e8-0ef6-5a5b8636dfbd@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 31D0D140006 X-Stat-Signature: qct3jp4yhkaebgdfjh5bqz5s9pgfsy4d X-Rspam-User: X-HE-Tag: 1675851244-589847 X-HE-Meta: U2FsdGVkX1/QyQ/oaiuP4qfUIcfgZcjnyxLUnEnRkaVtuY1o6O1PO71piQLafg6MuxTDwMWlSkJWyXRPPX7W8IaNwrvjR5QxDs4JGXQ7sCuj/7kN9agDPq3LETnOTa3DYlO7ila81fAN0/6fDK+NudfZb3xklAL56ZnA/bSAUGCwE//+KExBYySYRvNTrq0fQfBWRvllznHbuni+oaAAG/aXNMpWlf49/sTeBvh/VbxoXGg835s667whyCrV19tsPm+llgTbPydiGBg6Ynpf49aVG3fRpWsZtnnKoVit98dBnmwefJa6MPuezb6dUwJ1RplcMNOJoV2Up1+jNSPKpyXawREuRjq3CSIjLDTS8GR1a7Syhhh1f36SPUakRInVVRMOXh0P+OZFk7xnYWrkurYTISss4ALgplUja9XPPoSENqUqdqmBjxP5iLBBy7xdZ6f5VHuRLW5qzrrjiBYR44IkDKzbRMi8XB8oXLlEcODwS6vnnwQ/YMU6T7xF2bi8IGE1q+971XFPIsNiiH8JcND27fA99RnqqdMfQdSfpw4DcgOXIoPMcUr6HxtI0HCWb+ZWIGvv7PVmqo+rtjCOCK8xwGlhRj4+zPnFDvKHJhw4GMrop7iXPUrltWC0WOLi9eDot+plkJeQE0GX4oCvTFf5rDn4crJM63e6lRtWQ6lCPLuvtQXnefOsRzuaLRfnydRcYjVH2d+NuhRFFquMGjyoqwBd3ji0OfXir1uQ4oQr2GsmqRkpyW7LVxAl9z2OQ7T86z7YXBWuujYdiNq1cWVkG0fpi3+Vj043LOt1wMIenqXft9+VAI7zldQGQASfnIeJB7EvuP3d8EjIXVNyNi2qq2iwKw98ttSLFtv8EjdNQoRjzqm8WkLupTgbKLevayqRQJI+eUNKKk9mLlgVG8Pi1PCAE2mMhamYlpCK9PT0y0kGHvkWvu3G4VJa6yr3TJK8IgSpDMhSSMdPn2e unA7gTbA dN4RxgjYwsTQNv1gexvvLbjfyUHM4wUonrExaWTGqLSvMsnajI4hkd10yceV5PwNBcH8wfakbBLbm08iM2sw3avuuUsofBMJAwIxPL7s7c7472td/SiMRMwp29dEJQg653blPP+FjpC2gsr9r9EvB4gBGMDvo0qa6VKLbYPbE8QEdAfSenJiEU+RsKJCKLRz0zgAae0U17oE0HxEyLWqBcpxonaxvO+0Ht2q/bJmPbuLpu4iBhYqVZUBdZIyj5HG1motRkcXXW2rcnxUcxcCt9q/zeHJP/J/Wi2Vga8y4D3Z8r8oJ/TDhPMyunvasU1Zxqo3XQlq9fT8xk/9AYE0l375DHCi9CaKnx8tT/8lhruEba6HYu/xP7nlMe42+B8YGUI/6lsMzTHjJtfYBxfF9LnaORrEBFhDKJ0HT/7WtQfB0cLo= 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 08.02.23 10:44, Mike Rapoport wrote: > On Fri, Feb 03, 2023 at 05:04:01PM +0100, David Hildenbrand wrote: >> On 30.01.23 06:11, Matthew Wilcox wrote: >>> On Mon, Jan 30, 2023 at 01:34:59PM +0900, Hyeonggon Yoo wrote: >>>>> Seems like quite some changes to page_type to accomodate SLAB, which is >>>>> hopefully going away soon(TM). Could we perhaps avoid that? >>>> >>>> If it could be done with less changes, I'll try to avoid that. >>> >>> Let me outline the idea I had for removing PG_slab: >>> >>> Observe that PG_reserved and PG_slab are mutually exclusive. Also, >> >> I recall that there are SetPageReserved() calls on pages allocated via slab. > > I did a quick scan, and it seems that all allocated reserved pages come > from alloc_pages() or vmalloc(). > Thanks for checking, good that my memory was wrong :) > BTW, looking at the current usage of SetPageReserved, it seems that some > are bogus/historical and some would justify a different page type if we are > to have 15 bits for PG_kernel. I remember raising in the past that something like PG_hole might be helpful. I also recall that most SetPageReserved usage in drivers is to make ioremap happy. PG_ioremappable or smth like that would be better. So yes, that would even help to cleanup the existing PG_reserved usage. -- Thanks, David / dhildenb