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 0DED947A87E; Fri, 2 Oct 2026 12:12:42 +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=1790943164; cv=none; b=kzBadtFVTU6mO58DnBYSuQCPvhX7kr2gYJl1Jlji3q0/rMj+0CHm2hznCtUXgBo0Nb7rrVuLReOkfLF+RU+RqzWMR3i9BhI+ijULje3GLyyyuNTWnMdrQslM79OruX9qRl1UMC+LmTmYLKW7rN/DglyiY0ejJ/8zCKYaiPBlFUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790943164; c=relaxed/simple; bh=ZJ0Z/r4AiXTZAF8k8QwJ7RvpIWIKMzp9yZ5KsTu0k1c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nOeQQAfo1YyH7hFaDJJ8pUQXdVynPHoc8tLxW9kq3ePMtfBKZK/rDD7Xo3w3sZmOp34S8X8QbKtRPV+9IsYz4w9tLdNl/Up70FryHz3SJsorSkeHKbyvrzcfxiNxq6q371iQyNZjc6+Hgixb+kOfHbsbELyhgHQL217XOpvro+k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=c4yl8biB; 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="c4yl8biB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B7891F000FF; Fri, 2 Oct 2026 12:12:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790943162; bh=nX94dzJL8Kj3ESX88e5wjImNlNtcKNqoM+7SGcE8uW0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=c4yl8biBSZCOSz8O02PAfeH7eOGxEphl+j5zx68yHK0rGgywavDJhETeCqFXtb525 drYTuH322sqP8NPQ5ZewzHTnVOIMhBthJu+BRfYK/9P82Fewt1qESLmLaBje/QXlbU DwFWnhrzPDhC7iHk2BYxuuux04WkpQ1QaA4z1giCRe1/CYf+j/udPDx9BpMRBgE+zE 0Pp4Nr8nepmdcGz6T4V/ZJP/q0Yksmr01oznoU9EHFYDe+Pybk4DVG6cBSpehyP9Up XaZfWzb0H55uTLR1CMcTUrzHQC2okp7EhDFf3/godjZFN6JSYYuusCC9eACzBjmltf QSU/lT7DTm+dw== Date: Fri, 2 Oct 2026 13:12:20 +0100 From: "Lorenzo Stoakes (ARM)" To: Lance Yang Cc: linux-mm@kvack.org, "Liam R. Howlett" , Andrew Morton , Jann Horn , Pedro Falcato , David Hildenbrand , Suren Baghdasaryan , Mike Rapoport , Vlastimil Babka , Michal Hocko , Jonathan Corbet , Paul Moore , Leon Romanovsky , Greg Kroah-Hartman , Dennis Dalessandro , Jaroslav Kysela , Jason Gunthorpe , Thomas Gleixner , Usama Arif , Dave Hansen , linux-kernel@vger.kernel.org, Kumar Kartikeya Dwivedi , Daniel Borkmann , Eduard Zingerman , Zi Yan , Nico Pache , Namhyung Kim , Ryan Roberts , x86@kernel.org, Dev Jain , Barry Song , Kiryl Shutsemau , "Martin K. Petersen" , Baolin Wang , "James E.J. Bottomley" , Simona Vetter , Peter Xu , Masami Hiramatsu , Sebastian Reichel , Borislav Petkov , Arnaldo Carvalho de Melo , Harry Yoo , Rik van Riel , Peter Zijlstra , Helge Deller , Mark Rutland , Ingo Molnar , Juri Lelli , Maarten Lankhorst , Vincent Guittot , Thomas Zimmermann , Catalin Marinas , Nhat Pham , Gerald Schaefer , Maxime Ripard , Nick Piggin , "Aneesh Kumar K.V" , Muchun Song , Marc Zyngier , Will Deacon , "Matthew Wilcox (Oracle)" , Arnd Bergmann , Madhavan Srinivasan , "David S. Miller" , Paul Walmsley , Anup Patel , Palmer Dabbelt , Albert Ou , Vasily Gorbik , Baoquan He , Andreas Larsson , Claudio Imbrenda , Kemeng Shi , Gregory Price , Rakie Kim , Christian Brauner , Alistair Popple , Axel Rasmussen , linux-doc@vger.kernel.org, Alexander Viro , Matthew Brost , Ying Huang , Byungchul Park , Joshua Hahn , Xu Xin , Chris Li , linux-usb@vger.kernel.org, Qi Zheng , Yuanchu Xie , linux-rdma@vger.kernel.org, selinux@vger.kernel.org, Youngjun Park , Chengming Zhou , Wei Xu , Miklos Szeredi , linux-sound@vger.kernel.org Subject: Re: [PATCH v3 10/40] drivers/usb/mon: update to use mmap_prepare + map kernel pages Message-ID: References: <20260917-b4-mmap-prepare-vma-flag-sanify-v3-0-4583d8a23bca@kernel.org> <20260917-b4-mmap-prepare-vma-flag-sanify-v3-10-4583d8a23bca@kernel.org> <90811f7b-1751-49cb-bf0b-3d5ee7f10e45@linux.dev> 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=us-ascii Content-Disposition: inline In-Reply-To: <90811f7b-1751-49cb-bf0b-3d5ee7f10e45@linux.dev> On Fri, Oct 02, 2026 at 05:55:56PM +0800, Lance Yang wrote: > > > On 2026/9/18 00:22, Lorenzo Stoakes (ARM) wrote: > [...] > > +static int mon_bin_discontig_init(void *vm_private_data, void **private) > > +{ > > + struct mon_reader_bin *rp = vm_private_data; > > + > > + /* Dropped by mon_bin_vma_close() on unmap, including on error. */ > > + __mon_bin_vma_open(rp); > > Em ... If Coda uses a usbmon container and the first page insertion fails > (e.g. -ENOMEM when allocating a page table) after mon_bin_discontig_init(), > where is mmap_active decremented? > > mmap_action_finish() returns the error when is_compat is true, and > mmap_file() then replaces vm_ops with dummy ops. > > Am i missing something? No, indeed, the contract isn't honoured in the compat path. It can't actually happen in practice - the compat layer is only ever accessed from a stacked filesystem and those only stack on regular files. But I should probably update this to be strictly correct regardless to be consistent with the non-compat path. Let me see if that looks sensible and rejig for v4, thanks! :) > > > + return 0; > > +} > > Cheers, Lance > > [...] -- Cheers, Lorenzo