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Thu, 12 Sep 2024 14:57:20 -0700 (PDT) MIME-Version: 1.0 References: <20240912185602.2342148-1-willy@infradead.org> In-Reply-To: From: Yosry Ahmed Date: Thu, 12 Sep 2024 14:56:44 -0700 Message-ID: Subject: Re: [PATCH] bootmem: Stop using page->index To: Matthew Wilcox Cc: linux-mm@kvack.org, x86@kernel.org, Mike Rapoport Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: dyu7yhqoi7a5djp3h9cgzaozjw17sizn X-Rspamd-Queue-Id: 5973CC0009 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1726178243-709962 X-HE-Meta: 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 Y810rcSi 5flt9IzUP77DOjqEPoo0hn8v3Ox2moMufFi/J+FO8Gkjr+Sq+cMdC6Yp9h2g4FiXzG55eF79ZfjdmerfK6AMYxCBC4jbjKu3WBhklAiUHFJCQWL0m+VwRYG15bGinmutVsJw1Rd4FbmCNYqGOgNY8zOidWcf042+5A0ASmdxdkt13m+vx+fgIM80x1zGKFEzUIzzLzoP2zLyA6/N2ATlOx/sRYCvQ1RrDPFrq X-Bogosity: Ham, tests=bogofilter, spamicity=0.055504, 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 2:51=E2=80=AFPM Matthew Wilcox wrote: > > On Thu, Sep 12, 2024 at 12:04:18PM -0700, Yosry Ahmed wrote: > > On Thu, Sep 12, 2024 at 11:56=E2=80=AFAM 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 *pgda= t); > > > > > > 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. It's not a big deal, but if we want to change the number of bits later we change one macro definition instead of 5 lines of code across two different files.