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 54C3A368D78; Wed, 2 Sep 2026 18:01:10 +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=1788372071; cv=none; b=bnJO9RAeNhXrEZlivqY0nRPJGVoLCWVtVVt2ojglIqXJ/8rR7BnQ63TzV4GOKTrCFFB0kQlekitArzn+d6t0rP/C9ucmGoaP0bnPJmFqtLqRhb9/YUmDcCpxKfmUtLZFI2lxTZha/rUnqby1KMBD52KPPaThaV9+nOFAp9LRLwE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788372071; c=relaxed/simple; bh=MuW0MgECKFqsgKYanDvHZ2zzAEiQ7iCtWQ9chN/jOZY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=a7k/QaVKX2SQvJ3ansWPVlXaFiaF9MprlFbN6XHp+jLAPC9TloUgtpRNW4RdxDW6g1MNdOrpWzRG8M901/suxFqUpSfvu/7FMamXm/k+76gbhb4A8Vl19t0/6JW2xw68vO4bOLoQvtU10pN8cO22xbbulvbJSzn9igGDgvqUp4o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aHevDBYl; 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="aHevDBYl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E87DA1F00A3A; Wed, 2 Sep 2026 18:01:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788372070; bh=7INaOtP/gm2Q0CwFqGyhMMm+FXe4/enBYyOAMoEMKqg=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=aHevDBYl5hjaNDNwhdaa8kY7f11J7SCp88tnXt+ak5jBNNMaNCZL/SLusgaHNCK/p SZK9/Y1HaQ+x9hnq/BEjr+Jny3I4XQV12hx0fC7aOkDw5uke0RQGFPEeQuvkqKMyrr 0WvkYPYhDB9F7/zmeNrKwq/onEoa1yXvZ5cH60X1b40vRUdiOkMTl2B2viY2Qd6yP1 4SJeiZIVXf3dYH6RVJ5WXuaNVVV6XkbNx5hZfC6qjhrLTcDiGSqVoAlI6zr9Lylkrx 9poIzuEr+0GEGqSLXCLnwbqno0TlpN3MYCs/drYw5DrjU9FgggUiglJXMEQ29by99m SqrfqhwqLkHWg== From: "Lorenzo Stoakes (ARM)" Date: Wed, 02 Sep 2026 19:00:22 +0100 Subject: [PATCH 5/6] tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon Precedence: bulk X-Mailing-List: linux-kselftest@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: <20260902-map-private-dev-zero-v1-5-a578c730cec7@kernel.org> References: <20260902-map-private-dev-zero-v1-0-a578c730cec7@kernel.org> In-Reply-To: <20260902-map-private-dev-zero-v1-0-a578c730cec7@kernel.org> To: Arnd Bergmann , Greg Kroah-Hartman , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , David Hildenbrand , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Hugh Dickins , Baolin Wang , "Matthew Wilcox (Oracle)" , Jan Kara Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, "Lorenzo Stoakes (ARM)" X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1881; i=ljs@kernel.org; h=from:subject:message-id; bh=MuW0MgECKFqsgKYanDvHZ2zzAEiQ7iCtWQ9chN/jOZY=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJmpHi9nvw5TIiDx717l+IWCYn9hvfbghpNU3+UHZhwd Ifr/36GjlIWBjEuBlkxRZbnX8T3B4mEzeu84O8GM4eVCWQIAxenAEzkmDkjwzuF0m63Ml359V7H NU1u3tJ+G1/wwdk+yDO64Ny5w3PjNzL8Yv678MJ/N2c2vfUGW7bmrdtdyCK598aDmPgrHVk5E5Z c4QcA 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. Acked-by: David Hildenbrand (Arm) Signed-off-by: Lorenzo Stoakes (ARM) --- tools/testing/vma/tests/mmap.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/tools/testing/vma/tests/mmap.c b/tools/testing/vma/tests/mmap.c index c85bc000d1cb..fa73faff2262 100644 --- a/tools/testing/vma/tests/mmap.c +++ b/tools/testing/vma/tests/mmap.c @@ -45,7 +45,44 @@ static bool test_mmap_region_basic(void) return true; } +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); + struct file file = { + .f_op = &zero_fops, + }; + 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