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b=PuHdcLS1JTZ9/r5Mr4tauz++6saoXfkiZkpk17nVpbDKcJKf9cDmGBG5lRKa/b/cb m5aHsmlaHkT+ptUZkhSvSlQLJ7I1GpFf0JpcIljNfrqqgYpiDBhQjkzQXsateYVWg+ 4FbzPzDDVXQjKSZ4+QTp7H2efjV4RdUOuR66Yb4kMI2VtBUj2/PlFtkJuSJYmjilVs RjSM2dUGGPJG7cvGItYbpQ/80J9wMK/LFMss6b+pi2qO4Q6AkoARLZVCO4kB3OKEej tA48zarkJbc+ndBT2e7reXXpM6FTtuqmG3Iu3b7Frg7nZbVhCMEUpDg4YXVhzR49jd w68UsR7xZn/nw== Message-ID: <8a6f0bc0-5b6d-406d-9d2c-d3861b5c31b5@kernel.org> Date: Mon, 6 Jul 2026 11:15:36 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 3/8] mm: add a set_page_section_from_pfn() helper To: Li Zhe , akpm@linux-foundation.org, apopple@nvidia.com, arnd@arndb.de, bp@alien8.de, dave.hansen@linux.intel.com, kees@kernel.org, mingo@redhat.com, rppt@kernel.org, tglx@kernel.org Cc: linux-arch@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org References: <20260701090553.62691-1-lizhe.67@bytedance.com> <20260701090553.62691-4-lizhe.67@bytedance.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: EB06C20006 X-Stat-Signature: y7jk354pegpemhf8cfuyx3ziq3cxsggh X-HE-Tag: 1783329342-172124 X-HE-Meta: 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 mYSZcbQB 6a3fmE1KbjN45x/PqKXFcEIte0PU1EG3axJ3w5W+A9n2uE24t2GVrdH99bKF60HGZxhMwVoTu/PUh1WITxLo4vMsIfjEiP/XK07OpkxzU4lTXTXTNFqK97uShAmTd3y+27Idseo1/js8Y0t61CyWLbjwpjBz7rkkfHkVdr57fjG2nTnLFkw0Q7IHkVYLjE0jYiXe4RGqtYmpSlXu6R7ruiQJ7nnFG51E5hPJl0ijBnOr6i0meAvg6x/HtNbm6HDal8Om0DSyfF3nC2EBnrn/fkw5Eu/wVL/ccQDSymkrVXFAVFvPahrjVbSuOeo3BlTYYoZcyJHM+wrLp7Yrqm3WUIIrl+l3PdnQBquRA Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/1/26 11:05, Li Zhe wrote: > Callers that want to update section bits from a PFN currently need to > open-code: > > set_page_section(page, pfn_to_section_nr(pfn)); > > and guard that sequence with #ifdef SECTION_IN_PAGE_FLAGS. > > Add set_page_section_from_pfn() to wrap that update in one place. When > section bits are stored in page flags, the helper derives the section > number from the PFN and updates the page flags. Otherwise it degrades to > a no-op. > > Convert set_page_links() to use the new helper so later ZONE_DEVICE > fast-path patches can also update section bits without open-coding > SECTION_IN_PAGE_FLAGS at each callsite. > > This keeps the PFN-to-section translation local to the configurations > that actually store section bits in struct page flags, and avoids > exposing that detail to generic callers. > > No functional change intended. > > Signed-off-by: Li Zhe > Reviewed-by: Mike Rapoport (Microsoft) > --- > include/linux/mm.h | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 485df9c2dbdd..f78afa63dd3d 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2541,11 +2541,26 @@ static inline void set_page_section(struct page *page, unsigned long section) > page->flags.f |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT; > } > > +static inline void set_page_section_from_pfn(struct page *page, > + unsigned long pfn) Two tab indent. > +{ > + set_page_section(page, pfn_to_section_nr(pfn)); > +} > + > static inline unsigned long memdesc_section(memdesc_flags_t mdf) > { > return (mdf.f >> SECTIONS_PGSHIFT) & SECTIONS_MASK; > } > #else /* !SECTION_IN_PAGE_FLAGS */ > +static inline void set_page_section(struct page *page, unsigned long section) > +{ > +} Why do we need this? > + > +static inline void set_page_section_from_pfn(struct page *page, > + unsigned long pfn) > +{ > +} Dito. > + > static inline unsigned long memdesc_section(memdesc_flags_t mdf) > { > return 0; > @@ -2768,9 +2783,7 @@ static inline void set_page_links(struct page *page, enum zone_type zone, > { > set_page_zone(page, zone); > set_page_node(page, node); > -#ifdef SECTION_IN_PAGE_FLAGS > - set_page_section(page, pfn_to_section_nr(pfn)); > -#endif > + set_page_section_from_pfn(page, pfn); > } > > /** -- Cheers, David