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 6987544998C; Fri, 10 Jul 2026 20:22:56 +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=1783714977; cv=none; b=D0+WY/rbAeduXB1e1yCNmrRd31RuVYnrOnitUQ7rYimdRwkw/5Gyd/kNzGiFxZ/4YDiCAlhR6GQUZjvpxc6WGJfyvNUdvQjTocvhavBO2yT0B/iBnfn9pJ8A17/zLTq5gBdkC7vE/+CGvyTT8R8JTthc8tcv4WcFXgC66/fNDUk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783714977; c=relaxed/simple; bh=Ckq9F1B5R4ctEUJqWXYT1jV2i9Vim92hn6PkYJsjcDc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=QvhB/8j2xglgO6RbQMop7fwUrxcbfK6JuMHyESNHhgZSaSrv0OYjmnMIxj1ePJHB3p6Xed9j/mno9lNMcIMvkEEZT9lQGTWdmMNoEVJDdgATLjCNS9amt4WDKtkYRGdGgDEa4aNlYo7DhPh6U1O1L2hdR+VEGgOnHK3Q7zyiDh0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BygF57wD; 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="BygF57wD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C69F1F000E9; Fri, 10 Jul 2026 20:22:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783714976; bh=g95Hx/jZszTYl/mqKEmmLN3wpFLfcUCiQ7oLxyYPtwI=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=BygF57wD+F4oIx2IjGBmXSgdeyH+kDz20QKqfZkY+JeciaIqrpYGeXs92Dhu1bJQg yDrXtWAFvHrGJ01GVLJpGEYigWux3ULkArB6G87U6BG+mND6GeRsCRQIqxn7ZB/Co7 WX5bQzX3DHLJV8P5v5PFCfG2UwKM4+ICy3syuuKgzN0aQLrIra+79BjIq5f/isekmS 4O/AIhZQ8j5j/Q1gq+aeN84CaAkEZVoCKAwBtKJrHGY5odfGQwzjga9mJoIKacknvz VLOYvIoanmU23sKzVnBYRU2knQpn2FpJ7GQeLdVOWXN6EA1E/tTlccruzKODHlic/F MkoQCxvPMfndg== From: Lorenzo Stoakes Date: Fri, 10 Jul 2026 21:16:55 +0100 Subject: [PATCH v2 14/33] mm/vma: clean up anon_vma_compatible() Precedence: bulk X-Mailing-List: linux-trace-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: <20260710-b4-pre-scalable-cow-v2-14-2a5aa403d977@kernel.org> References: <20260710-b4-pre-scalable-cow-v2-0-2a5aa403d977@kernel.org> In-Reply-To: <20260710-b4-pre-scalable-cow-v2-0-2a5aa403d977@kernel.org> To: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Rik van Riel , Harry Yoo , Jann Horn , Lance Yang , Pedro Falcato , Russell King , Dinh Nguyen , Simon Schuster , "James E.J. Bottomley" , Helge Deller , Alexander Viro , Christian Brauner , Jan Kara , Dan Williams , Matthew Wilcox , Muchun Song , Oscar Salvador , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Miaohe Lin , Naoya Horiguchi , Xu Xin , Chengming Zhou , SJ Park , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Hugh Dickins , Peter Xu , Kees Cook , Marek Szyprowski , Robin Murphy , Andrey Konovalov , Alexander Potapenko , Dmitry Vyukov , Steven Rostedt , Mathieu Desnoyers , Jarkko Sakkinen , Dave Hansen , Thomas Gleixner , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Ian Abbott , H Hartley Sweeten , Lucas Stach , Christian Gmeiner , David Airlie , Simona Vetter , Patrik Jakobsson , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Rob Clark , Dmitry Baryshkov , Abhinav Kumar , Jessica Zhang , Sean Paul , Marijn Suijten , Tomi Valkeinen , Thierry Reding , Mikko Perttunen , Jonathan Hunter , Christian Koenig , Huang Rui , Matthew Auld , Jason Gunthorpe , Yishai Hadas , Shameer Kolothum , Kevin Tian , Ankit Agrawal , Alex Williamson , Paolo Bonzini , Shakeel Butt , Usama Arif Cc: Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, damon@lists.linux.dev, iommu@lists.linux.dev, kasan-dev@googlegroups.com, linux-sgx@vger.kernel.org, etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, linux-tegra@vger.kernel.org, kvm@vger.kernel.org, Russell King X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=1642; i=ljs@kernel.org; h=from:subject:message-id; bh=Ckq9F1B5R4ctEUJqWXYT1jV2i9Vim92hn6PkYJsjcDc=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLICg20UN7HtLM/vyXsTFrxVYsWpHDm18w4P5+XM12s5+ WWHrvf0jlIWBjEuBlkxRZbnX8T3B4mEzeu84O8GM4eVCWQIAxenANzkqYwMU33rlv+/mL9e+HWT WHxes/ljhqb8yMyVr44wrbuqccd5DcNfmT/8Ns92pKWUmxwKXbLj7ZqLidpWFw45HF1j+zc0qX0 fGwA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 Break up the existing very large conditional, add comments and use vma_[start/end]_pgoff() to make clearer what we're doing here. No functional change intended. Reviewed-by: Gregory Price Reviewed-by: Pedro Falcato Signed-off-by: Lorenzo Stoakes --- mm/vma.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/mm/vma.c b/mm/vma.c index 995de8198fbb..084afdf37385 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -1967,14 +1967,25 @@ static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct * { vma_flags_t diff = vma_flags_diff_pair(&a->flags, &b->flags); + /* Ignore flags that mprotect() can change. */ vma_flags_clear_mask(&diff, VMA_ACCESS_FLAGS); + /* Ignore flags that do not impact merging. */ vma_flags_clear_mask(&diff, VMA_IGNORE_MERGE_FLAGS); - return a->vm_end == b->vm_start && - mpol_equal(vma_policy(a), vma_policy(b)) && - a->vm_file == b->vm_file && - vma_flags_empty(&diff) && - b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); + /* Must be adjacent. */ + if (a->vm_end != b->vm_start) + return false; + /* Must have matching policy. */ + if (!mpol_equal(vma_policy(a), vma_policy(b))) + return false; + /* Must both be anon or map the same file (MAP_PRIVATE case). */ + if (a->vm_file != b->vm_file) + return false; + /* Flags must be equivalent modulo mprotect(). */ + if (!vma_flags_empty(&diff)) + return false; + /* Page offset must align. */ + return vma_end_pgoff(a) == vma_start_pgoff(b); } /* -- 2.55.0