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([181.229.23.179]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-67d8a4339c3sm2844892d50.3.2026.11.13.11.38.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2026 11:38:18 -0800 (PST) From: Ivan Ezequiel Rodriguez To: Andrew Morton , David Hildenbrand Cc: Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , linux-mm@kvack.org, linux-kernel@vger.kernel.org, =?UTF-8?q?Iv=C3=A1n=20Ezequiel=20Rodriguez?= , stable@vger.kernel.org Subject: [PATCH] mm: use PFN_PHYS() in phys_mem_access_prot() Date: Fri, 13 Nov 2026 16:38:12 -0300 Message-ID: <20261113193812.1239880-1-ivanrwcm25@gmail.com> X-Mailer: git-send-email 2.43.0 X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8C2FE20002 X-Spam-Status: No, score=-14.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,HK_RANDOM_FROM,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Stat-Signature: gbci3yqc83imn8tz9ngien59c3tkxc1r X-HE-Tag: 1794598700-736001 X-HE-Meta: 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 MzWtgVuh 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 From: Iván Ezequiel Rodriguez phys_mem_access_prot() stores "pfn << PAGE_SHIFT" in a phys_addr_t. The shift is evaluated as unsigned long, so on a 32-bit kernel with CONFIG_PHYS_ADDR_T_64BIT an address above 4 GiB is truncated before uncached_access() compares it with __pa(high_memory). mmap_mem_prepare() already shifts in phys_addr_t, so the mapping is accepted and then left cacheable. PFN_PHYS() casts before the shift. On a MIPS32 XPA Malta guest, mmap of /dev/mem at 0xf00000000 without O_DSYNC used the boot CCA. The same mapping with O_DSYNC was uncached. With PFN_PHYS() both are uncached. Fixes: 7e6735c3578e ("/dev/mem: use phys_addr_t for physical addresses") Cc: stable@vger.kernel.org Signed-off-by: Iván Ezequiel Rodriguez --- mm/char-mem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/char-mem.c b/mm/char-mem.c index c5761ddedbd7..53ce0034a4c1 100644 --- a/mm/char-mem.c +++ b/mm/char-mem.c @@ -272,7 +272,7 @@ static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { #ifdef pgprot_noncached - phys_addr_t offset = pfn << PAGE_SHIFT; + phys_addr_t offset = PFN_PHYS(pfn); if (uncached_access(file, offset)) return pgprot_noncached(vma_prot); -- 2.43.0