From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D968BC624D3 for ; Wed, 2 Sep 2026 18:01:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EECCF6B00DC; Wed, 2 Sep 2026 14:01:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E9CB96B00DD; Wed, 2 Sep 2026 14:01:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D8CDD6B00DF; Wed, 2 Sep 2026 14:01:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 9E0C26B00DC for ; Wed, 2 Sep 2026 14:01:17 -0400 (EDT) Received: from smtpin14.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 2A910120349 for ; Wed, 2 Sep 2026 18:01:17 +0000 (UTC) X-FDA: 85169588994.14.37EA753 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf28.hostedemail.com (Postfix) with ESMTP id 54E0FC0015 for ; Wed, 2 Sep 2026 18:01:15 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=d1FKV9YY; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788372075; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=gKMN/4ga+akQkR+gCUDsGByPhFMGOkvrwnVsmryglD8=; b=W8hy6/bpIGTYQ7YQmXMb3XqMG8iMjZyr9a2okc8TN4QbNn6SxyL3IVwAMll5qymBzieCU4 bonqZQCxhDf0pu+UPs0FnNBHk7tJvOxps5GdNf2qfn2uz77V4pwwzqGkuiBSoqyzxKuTlL yum6wpoCPC77+eKlx3naPW0CfZJY7oI= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788372075; b=Tg4lueIv14TZ14axDGSrJXQRZWVExyjvzjUyItaW3wvgNJOU1I9/SmYFe7++yV4a8yXDFh GTQDlF+vm8ooKRta3eSJabGKCmZ1Jd7uuR1PO4efx4vjwGdNZ6ajZvMz8XnSdMt3+f+9wm zsC6RJLt1QNjvLE8D7E/F/WgAaNelco= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=d1FKV9YY; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf28.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 95DCF44506; Wed, 2 Sep 2026 18:01:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72A4C1F000E9; Wed, 2 Sep 2026 18:01:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788372074; bh=gKMN/4ga+akQkR+gCUDsGByPhFMGOkvrwnVsmryglD8=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=d1FKV9YYgYwhR45HYlw7ao5vs9Wvz7PH7HdW6abQ3+PLbGWWvZo+3YkL2712FNcj3 eFB3FqAWjSUj+yOdKG8HVSn91Hj33qCCBkTf4fY5KlCUwk8LWC/p+mBfsSR5DnKUiv zhJY6+WmVzQqCI3nQq9Be6MCrPz/Eynxla55ntnaJM6OZU/sEqproc8yvTFMEcQWrQ eG87GbKzRQfMfugp1SyOaQoerezIFaaZibVV2aRufhYlYB6wVAJNTzBiQo8Z/9TAeJ 6/I5figxrew5gszJrQH9r3n1eOfh3ulOJKEDhuPwsCKtrOg0tOiipteEvSpi0Rzec2 kmSKNsyOBD/9Q== From: "Lorenzo Stoakes (ARM)" Date: Wed, 02 Sep 2026 19:00:23 +0100 Subject: [PATCH 6/6] tools/testing/selftests/mm: add MAP_PRIVATE-/dev/zero merge tests MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260902-map-private-dev-zero-v1-6-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=4280; i=ljs@kernel.org; h=from:subject:message-id; bh=6y4SgQpQz3RLpexZGYRim0KFzXiNKV69KBfjEhHHVH0=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLJmpHjNspi7c//R9qnWvN3MzKq2h9cVHb91el5GlePJx AUbDF6/6ShlYRDjYpAVU2R5/kV8f5BI2LzOC/5uMHNYmUCGMHBxCsBEWhMZGa6e/NO3dpKZDHd8 SbPov0Khpf26ryc8Xx3y77RUo+xE11UMf6XV3rybEF3BPn1ybYZMjtSSYidPjSe/6r7wZV45bLb gGxcA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 54E0FC0015 X-Stat-Signature: 8dhyn8wg5gmwd8o3qsoeki5ie6dz4h8k X-Rspam-User: X-HE-Tag: 1788372075-746312 X-HE-Meta: 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 xVyqnTdf xQdYYJfvlOHuICtM8TJwbVq9VWhDp2ueFyalqs17QVFgJ3bGo+hi9v0VpxcRJAmagvz62GCIUpRReg+yctJrh1D1xpVVkzTBs+03+DULmjtlZV/9J2H6LN8yRgyUmYpZv9lqfW95OANEpjJLfGM+LTYjgNPzg6PKlP0DJtDQHAjcFj3Zc26BuqdBjWZW8olGSEq5KZuNUcm6WfQ7luiZ1ZxrXLaXmZjJn7y25vVEqJuTjfoRVlumxwzCuQeVZyMno8ZyMEJ5zjiQKtKQGdwdcBQAgd85UA7RBITKs1G62wCq4Y8E= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Assert that MAP_PRIVATE-mapped /dev/zero mappings behave like they are anonymous. We test both unfaulted and faulted/unfaulted merges - each with the regions having page offset of 0, which would not merge if the mappings were treated as if they were file-backed. With the recent change that makes them behave as pure anonymous mappings, the merges should succeed as their page offsets are equal to their anonymous page offsets. Signed-off-by: Lorenzo Stoakes (ARM) --- tools/testing/selftests/mm/merge.c | 104 +++++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+) diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c index 52b8727b6628..7c528d470404 100644 --- a/tools/testing/selftests/mm/merge.c +++ b/tools/testing/selftests/mm/merge.c @@ -1362,6 +1362,110 @@ TEST_F(merge, anon_and_page_offset_mismatch_memfd) ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 5 * page_size); } +TEST_F(merge, merge_map_private_dev_zero_unfaulted) +{ + struct procmap_fd *procmap = &self->procmap; + unsigned int page_size = self->page_size; + char *carveout = self->carveout; + char *ptr, *ptr2; + int fd_zero; + + if (access("/dev/zero", F_OK)) + SKIP(return, "No /dev/zero."); + fd_zero = open("/dev/zero", O_RDWR); + ASSERT_NE(fd_zero, -1); + + /* + * Map two MAP_PRIVATE-/dev/zero VMAs next to one another with offset 0 + * each. + * + * With these being made truly anonymous upon mapping, they will + * merge. If they were file-backed VMAs the page offsets would prevent + * merge: + * + * |-----||------| |-------------| + * | ptr || ptr2 | -> | ptr | + * |-----||------| |-------------| + */ + ptr = mmap(carveout, 5 * page_size, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE, fd_zero, 0); + if (ptr == MAP_FAILED) { + close(fd_zero); + ASSERT_TRUE(false); + } + ptr2 = mmap(&carveout[5 * page_size], 5 * page_size, + PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, fd_zero, 0); + if (ptr2 == MAP_FAILED) { + close(fd_zero); + ASSERT_TRUE(false); + } + close(fd_zero); + + /* Assert that they merged. */ + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 10 * page_size); +} + +TEST_F(merge, merge_map_private_dev_zero_faulted_unfaulted) +{ + struct procmap_fd *procmap = &self->procmap; + unsigned int page_size = self->page_size; + char *carveout = self->carveout; + char *ptr, *ptr2; + int fd_zero; + + if (access("/dev/zero", F_OK)) + SKIP(return, "No /dev/zero."); + fd_zero = open("/dev/zero", O_RDWR); + ASSERT_NE(fd_zero, -1); + + /* + * Map a MAP_PRIVATE mapping of /dev/zero with page offset 0, then fault + * it in: + * + * |-------------------------------| + * | faulted | + * |-------------------------------| + */ + ptr = mmap(carveout, 15 * page_size, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE, fd_zero, 0); + if (ptr == MAP_FAILED) { + close(fd_zero); + ASSERT_TRUE(false); + } + memset(ptr, 'x', 15 * page_size); + + /* + * Unmap the middle: + * + * |---------| |---------| + * | faulted | | faulted | + * |---------| |---------| + */ + ASSERT_EQ(munmap(&ptr[5 * page_size], 5 * page_size), 0); + + /* + * Map in a new unfaulted mapping in the middle with page offset 0 - + * this should merge and would not if it were treated as a file rather + * than pure anon: + * + * |---------|-----------|---------| + * | faulted | unfaulted | faulted | + * |---------|-----------|---------| + */ + ptr2 = mmap(&carveout[5 * page_size], 5 * page_size, + PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, + fd_zero, 0); + close(fd_zero); + ASSERT_NE(ptr2, MAP_FAILED); + + /* Assert that they merged. */ + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 15 * page_size); +} + TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev) { struct procmap_fd *procmap = &self->procmap; -- 2.55.0