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Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1sorjA-0000000BNFO-1Rng; Thu, 12 Sep 2024 21:51:48 +0000 Date: Thu, 12 Sep 2024 22:51:48 +0100 From: Matthew Wilcox To: Yosry Ahmed Cc: linux-mm@kvack.org, x86@kernel.org, Mike Rapoport Subject: Re: [PATCH] bootmem: Stop using page->index Message-ID: References: <20240912185602.2342148-1-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 8AA9B1A0004 X-Stat-Signature: yi8e8p8j8fg9wn64qmcoihcimimn9k8s X-HE-Tag: 1726177910-912643 X-HE-Meta: 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 rdwWYn/A A5KrfPsf/sKgmQoTL7cfz+QgZHzKMXC9OQwtBsCOKpmr0t13ymRzaBieeWEfU/HaI8FP5230rinTYLKRCoNHbQn+XBLnSXUc2tPEmzDWWwpBB5GCx4Lq8XyZ0rgHr7s4L7AhpnoRwH9xdcsSCz3rHlL5DGH+b/EduW3K+EwZPvBBELolQ3Dh/+ssMqbEJhm99SsfwYIz/3xYz6gnPdTVV/SdaBj5Iu4eGgcSSFSKlnIVupv6F44G7MjwME//ucM48e+tjMlm/cXySzJ4SUpljYfDIMKs1cI4DbEHc 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: List-Subscribe: List-Unsubscribe: On Thu, Sep 12, 2024 at 12:04:18PM -0700, Yosry Ahmed wrote: > On Thu, Sep 12, 2024 at 11:56 AM Matthew Wilcox (Oracle) > wrote: > > > > Encode the type into the bottom four bits of page->private and the > > info into the remaining bits. Also turn the bootmem type into a > > named enum. > > @@ -21,9 +20,19 @@ enum { > > void __init register_page_bootmem_info_node(struct pglist_data *pgdat); > > > > void get_page_bootmem(unsigned long info, struct page *page, > > - unsigned long type); > > + enum bootmem_type type); > > void put_page_bootmem(struct page *page); > > > > +static inline enum bootmem_type bootmem_type(const struct page *page) > > +{ > > + return (unsigned long)page->private & 0xf; > > +} > > + > > +static inline unsigned long bootmem_info(const struct page *page) > > +{ > > + return (unsigned long)page->private >> 4; > > +} > > Would it be better to define the number of bits used for the type as a > macro and use it throughout (bootmem_type(), bootmem_info(), > get_page_bootmem())?. I think this is an adequate abstraction already.