From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA67346982F; Wed, 29 Jul 2026 16:50:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785343851; cv=none; b=otk4qa3ZCQ9om0DRxhNPOBXa4pkifPnzbDiQKfObPRIJpNCSTa4Yq0VJY3O6/YX8JnJo5tjRgvG0ysPcehzYZOQBJOvZ8iDAdB3OSPgp/li210TzG3GM3jeXoddFHjkBeD3q7KBO/vykp8lnn2uBTeGyZV/Ns54l7dHaUxTIozY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785343851; c=relaxed/simple; bh=LrCX7jlOp0eZY4mbJRb88uMuNt7kQbBaeHu5WfpNvf8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=G9x/L45gE4y/8UZXXTXAWMFNtXVvLo535pGNPgJStTNNhyjQ5ghJjSgkx4bRpdIlz1UiGHdg2JGfM2zbTkhVsZtAZ4vazfByimLwidK5M7naun1XzR0sLYw/zo1MQTRtQpBpbxzpzbafLMvzQ/THM3ltyU1pNK2a8oy2OMI1ZkA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mIct7j6h; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mIct7j6h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5759C1F00A3D; Wed, 29 Jul 2026 16:50:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785343849; bh=KczwmOEkPfLLbqBnfEvcAyssnLq2RkwLW6Rzj5IDQO0=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=mIct7j6hBj5KGgO3qOm4HxySF/V1bE5mr+ovPGakDXbD7cNspMw89i504mYM48ICY kfaEh5IUOPmyn6jn9yAL5Y+Lyo9qTCWA/ng0usBgQ+0g6EGRMKPw1mv5NTtuarAQnn j+6BGMLVPyAcfTrOn4CdVrSFAMJbFoJ4EgKGM3Ww/BSvHJnD+jtIg5vgaCdCxTk1jA rIiOeszyx9WXZZRaks4Tfy09vAFQuvSAsayOIHTO1HB+eRN6mcg71b6/RLD5ib80Eq bA1c7UWTpUPk99gnk8uu9TkDD38YlbJz1LLGWoJ9ehT0qnShZ4iPkeFd5eu2yfrfmD Nr/Qun1czJyPQ== From: "Lorenzo Stoakes (ARM)" Date: Wed, 29 Jul 2026 17:48:49 +0100 Subject: [PATCH v3 14/15] tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260729-b4-scalable-cow-virt-pgoff-v3-14-e8ecfefea812@kernel.org> References: <20260729-b4-scalable-cow-virt-pgoff-v3-0-e8ecfefea812@kernel.org> In-Reply-To: <20260729-b4-scalable-cow-virt-pgoff-v3-0-e8ecfefea812@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2651; i=ljs@kernel.org; h=from:subject:message-id; bh=LrCX7jlOp0eZY4mbJRb88uMuNt7kQbBaeHu5WfpNvf8=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLKy9H4yh64/1ySheGNjNctayxu3FB5q//1gPCVqxwQ/X 56XbrOYO0pZGMS4GGTFFFmefxHfHyQSNq/zgr8bzBxWJpAhDFycAjCRG1yMDJ231gqcOZzTMWne u+UeM9hMTWoC9/6N7recFOZ54Uqoli0jw24Gvzc3H6et5J1c1VxpUHK+fs31vDKHf5vfasxw/mf uzg8A X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Now we've made MAP_PRIVATE-mapped /dev/zero mappings truly anonymous, add a VMA userland test to assert that this is the case and everything is as we would expect for an anonymous mapping. Signed-off-by: Lorenzo Stoakes (ARM) --- tools/testing/vma/include/dup.h | 1 + tools/testing/vma/tests/mmap.c | 50 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 51 insertions(+) diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h index 556a57c48a75..b595e88ce98a 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -20,6 +20,7 @@ struct task_struct *get_current(void); #define MAJOR(dev) ((unsigned int) ((dev) >> MINORBITS)) #define MINOR(dev) ((unsigned int) ((dev) & MINORMASK)) +#define MKDEV(ma, mi) (((ma) << MINORBITS) | (mi)) #define S_IFMT 00170000 #define S_IFCHR 0020000 diff --git a/tools/testing/vma/tests/mmap.c b/tools/testing/vma/tests/mmap.c index c85bc000d1cb..ebe01362e530 100644 --- a/tools/testing/vma/tests/mmap.c +++ b/tools/testing/vma/tests/mmap.c @@ -45,7 +45,57 @@ static bool test_mmap_region_basic(void) return true; } +static int dummy_mmap_prepare(struct vm_area_desc *desc) +{ + return 0; +} + +static bool test_pure_anon_dev_zero(void) +{ + const vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, + VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT); + const struct file_operations f_op = { + .mmap_prepare = dummy_mmap_prepare, + }; + struct inode inode = { + .i_mode = S_IFCHR, + .i_rdev = MKDEV(MEM_MAJOR, DEVZERO_MINOR), + }; + struct file file = { + .f_inode = &inode, + .f_op = &f_op, + }; + struct mm_struct mm = {}; + struct vm_area_struct *vma; + unsigned long addr; + VMA_ITERATOR(vmi, &mm, 0); + + current->mm = &mm; + + /* + * Map a MAP_PRIVATE-/dev/zero mapping at address 0x300000 with a page + * offset of 0x10, which we expect to be reset to the anonymous page + * offset. + */ + addr = __mmap_region(&file, 0x300000, 0x3000, vma_flags, 0x10, NULL); + ASSERT_EQ(addr, 0x300000); + + /* Assert that it truly is an anonymous mapping. */ + vma = vma_lookup(&mm, addr); + ASSERT_NE(vma, NULL); + ASSERT_TRUE(vma_is_anonymous(vma)); + ASSERT_EQ(vma->vm_file, NULL); + ASSERT_EQ(vma->vm_private_data, NULL); + /* Expect anonymous page offsets. */ + ASSERT_EQ(vma->vm_pgoff, 0x300); + ASSERT_EQ(vma_start_anon_pgoff(vma), 0x300); + + cleanup_mm(&mm, &vmi); + return true; +} + static void run_mmap_tests(int *num_tests, int *num_fail) { TEST(mmap_region_basic); + TEST(pure_anon_dev_zero); } -- 2.55.0