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Mon, 26 Oct 2026 06:09:33 +0000 X-Mizu-Trace-ID: 530052733c7de91c X-Migadu-Flow: FLOW_OUT From: Ye Liu Date: Mon, 26 Oct 2026 14:09:23 +0800 Subject: [PATCH 1/2] mm/vmalloc: drop VM_DMA_COHERENT from remap_vmalloc_range_partial X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261026-vmalloc_remap-v1-1-b7a907814e90@linux.dev> References: <20261026-vmalloc_remap-v1-0-b7a907814e90@linux.dev> In-Reply-To: <20261026-vmalloc_remap-v1-0-b7a907814e90@linux.dev> To: Andrew Morton , Uladzislau Rezki Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ye Liu X-Mailer: b4 0.17-dev-39d60 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 8BB5AA0005 X-Stat-Signature: ahisaide6usu9b9ptmjr4akc4zixqod4 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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-Rspam-User: X-HE-Tag: 1792994974-74256 X-HE-Meta: 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 U+3hA11I MI5f/XEKBIhfwRkcBz/kp04qGv/z32oRKKME68UTIcbXuAMkiZy4Fx6PrT2EglJtPL7M9Mp3mMG274uCTwAP3MA/KS/9XsdY8VfTwDpqnkJGE7c6OM/HLEYzVAexVFOktbDlYhKy3q4Vl86ZwTg8GF5RzH8ZEtM8JXjn7c5DEXlF4+K8RkoklG6mNorexvaA2X/Seecza/WCZR/ikiItfzS/dznu/yQfOT9YbwV9fZ4lGUNTSsmSq8UJSSNvfqljJMfL1ujUR8Nt8gpW+RQM1YjYX75Ybm1JpknlL 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: Ye Liu No caller maps a VM_DMA_COHERENT area through this path: such areas come from dma_alloc_coherent() internals and are freed via vunmap(), never through remap_vmalloc_range[_partial](); all 13 callers pass vmalloc_user()/vmalloc()-backed addresses. The flag was added in commit fe9041c245196 ("vmalloc: lift the arm flag for coherent mappings to common code") as a mechanical translation of ARM's VM_ARM_DMA_CONSISTENT. It is also unsafe to keep since commit 5ea8ec74c57c0 ("mm/vmalloc: free unused pages on vrealloc() shrink"), which frees tail pages of non-VM_USERMAP areas (VM_DMA_COHERENT is not in that skip-list): a shrunk-then-mapped area would hit vmalloc_to_page()==NULL and vm_insert_page() would dereference it unchecked. Drop it so DMA-coherent areas can never enter the path. Signed-off-by: Ye Liu --- mm/vmalloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index db669103dc66..a888eca016a8 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4894,7 +4894,7 @@ int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr, if (!area) return -EINVAL; - if (!(area->flags & (VM_USERMAP | VM_DMA_COHERENT))) + if (!(area->flags & VM_USERMAP)) return -EINVAL; if (check_add_overflow(size, off, &end_index) || -- 2.43.0