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Tue, 20 Jan 2026 10:03:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id O6GYAfpSb2lgUgAAD6G6ig (envelope-from ); Tue, 20 Jan 2026 10:03:38 +0000 Message-ID: Date: Tue, 20 Jan 2026 11:03:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm/page_ext: Add page_ext_get_from_phys() Content-Language: en-US To: Mostafa Saleh , linux-mm@kvack.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: corbet@lwn.net, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, akpm@linux-foundation.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, xiaqinxin@huawei.com, baolu.lu@linux.intel.com, rdunlap@infradead.org References: <20260120091926.670155-1-smostafa@google.com> <20260120091926.670155-2-smostafa@google.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Queue-Id: E8A2F12000D X-Stat-Signature: 3pc6rf88tueeqk9gj1sh6og5rothr53k X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1768903419-790711 X-HE-Meta: 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 TFT/5adK 9XklkxO7jCghPavoS+0d4VyNnmBx0d9V31awo9sElMnhJYt9J7qNwCGNZbHj9mU6QGyvae5qzktvxTfJ/MkaYhWW+Pxd/TouBzW2UKd0fZ5zv40dfs3JylCfbNFQ61m9d2ILWWraLgxA6BJQrqI+HFyIoXXVp2tehyaMexaFLw0gWQgRMzZNS0P8aNb1+ZKiU9JkK7CHJg6cmk4mUZLIxDMXaPpjFDrxgzHQGo1lRu44Y2yNa2MNWUFcJBr5o2DplYhxRRNEekfpRy0/t/tjfhyJ4tP1hNt3a4fdkNnL6jz2Ni0pmIIVgVi+UuDbvmju34gK9LjV0jwkwjrz+cPRqb9V+qgiR7k6Ty4OQvUVR3o3rZpI= 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 1/20/26 10:19, Mostafa Saleh wrote: > The IOMMU code operates on physical addresses which can be outside > of system RAM. > > Add a new function page_ext_get_from_phys() to abstract the logic of > checking the address and returning the page_ext. > > Signed-off-by: Mostafa Saleh Acked-by: Vlastimil Babka > --- > include/linux/page_ext.h | 6 ++++++ > mm/page_ext.c | 23 +++++++++++++++++++++++ > 2 files changed, 29 insertions(+) > > diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h > index 76c817162d2f..61e876e255e8 100644 > --- a/include/linux/page_ext.h > +++ b/include/linux/page_ext.h > @@ -93,6 +93,7 @@ static inline bool page_ext_iter_next_fast_possible(unsigned long next_pfn) > #endif > > extern struct page_ext *page_ext_get(const struct page *page); > +extern struct page_ext *page_ext_from_phys(phys_addr_t phys); > extern void page_ext_put(struct page_ext *page_ext); > extern struct page_ext *page_ext_lookup(unsigned long pfn); > > @@ -215,6 +216,11 @@ static inline struct page_ext *page_ext_get(const struct page *page) > return NULL; > } > > +static inline struct page_ext *page_ext_from_phys(phys_addr_t phys) > +{ > + return NULL; > +} > + > static inline void page_ext_put(struct page_ext *page_ext) > { > } > diff --git a/mm/page_ext.c b/mm/page_ext.c > index 297e4cd8ce90..e2e92bd27ebd 100644 > --- a/mm/page_ext.c > +++ b/mm/page_ext.c > @@ -538,6 +538,29 @@ struct page_ext *page_ext_get(const struct page *page) > return page_ext; > } > > +/** > + * page_ext_from_phys() - Get the page_ext structure for a physical address. > + * @phys: The physical address to query. > + * > + * This function safely gets the `struct page_ext` associated with a given > + * physical address. It performs validation to ensure the address corresponds > + * to a valid, online struct page before attempting to access it. > + * It returns NULL for MMIO, ZONE_DEVICE, holes and offline memory. > + * > + * Return: NULL if no page_ext exists for this physical address. > + * Context: Any context. Caller may not sleep until they have called > + * page_ext_put(). > + */ > +struct page_ext *page_ext_from_phys(phys_addr_t phys) > +{ > + struct page *page = pfn_to_online_page(__phys_to_pfn(phys)); > + > + if (!page) > + return NULL; > + > + return page_ext_get(page); > +} > + > /** > * page_ext_put() - Working with page extended information is done. > * @page_ext: Page extended information received from page_ext_get().