From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793907355; b=X1T9IArWHaNKNlB9i5oMou0UA+/CKjoMpgvsn2/T2Fosni4mDPgiU8rKY4RBcQTbV59r LTFazpsP5tMFwSufvVleq2calxat0KpCQhhVlYIzq/Mi+89+VJ1IoeYaPO6KRpkxt+4HO ZKpnd0a49KSDLVq744TFzcbKAWKOzdb+ckhVRT/9mnNxt3eH426ytAkKXQL5oTySaAJAP FVLD0SJ4sXw2nVx/4F0xBCE6UdkugRWAvELAoqVe67lEus4l462SVpQBKdxVElkrwdwTy RmZr1P1MvHqcpqioIxGTF2hi/2a5OXNvnlvHFAsgWFdEGqE6j3UoY0mzN3/kIU238GA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793907355; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=Uq4i262WOQaYVL9uHrrjKQ33JdfPWVKPdUraeND3OfE=; b=vYRtReRW6C09ecXW46Gv5hKAeOarsqQP5S+LOaqn6mjORC0lTQF1D1iOdw6WiWqFWUfv SSOwxtIUFHTuxkNJOtEdnDbFhTRL76XLAU0xzwD34bbt8V+gABZKz6aGn0q8j56X283cC FqsOT/+n5vVZOtZDtWTUDIdybTmMO91bS3ax1WR2hWSw965F9lXKkgjktfOZcHkB5KLac zuTH4f9/C3qA/i6eMQomH4O+19FMMkbu1vAtNbYqdvKhztKHJZQ/u1SyOdsKM7uUfO9ja Ejxq3a+8uYnSrKA9xxxK3gJXjZQkHqL6MO8rmM5Q+sXIi4J5j2T/LVnARTquIaO0cuw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=lOvMqP+c; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E62C96079C34; Thu, 5 Nov 2026 19:35:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=lOvMqP+c Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4891D1F0089F; Thu, 5 Nov 2026 19:35:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793907354; bh=Uq4i262WOQaYVL9uHrrjKQ33JdfPWVKPdUraeND3OfE=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=lOvMqP+c6a7YXK9+H/ZuDenXtrEpHzLqnu+MIMYNNusWymGQVT1Q4/ec1t4w9PjCO qmkMvDH17i0eObC2beXzEFzADb2Xw2kymtYtn4SFw8ANhKSVhVpcnkQtfbpcSYZg9N 4l7J3MSm3a+sGzpZkH8kVTx2NrNd1TkZE3b0wDS9CPx8atrywkEgH3c4qaCIcxYIm9 dducVG4MRPcnbp0cfT9GmqSQ0uK/VKpBfmn2Z5AJsRGEKqgwI3kPTede2Uzq0Kx9jz cWMxxkM6AxN0Z0X5UmQGN06QpwBQ8vnODudNJE/T70S35JR+kfwyN2SPUyPEeWjKos Y2lpLs6jftrBQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH RESEND v2 19/23] proc: pin the entry around the vm_operations of its mappings Reply-To: sashiko-reviews@lists.linux.dev To: "Christian Brauner" Cc: "Linus Torvalds" , "Jann Horn" , "Josef Bacik" , "Chris Mason" , "Jeff Layton" , NeilBrown , "Eric Dumazet" , "Thomas Gleixner" , "Al Viro" , "Jonathan Corbet" , "Christoph Hellwig" , "Greg Kroah-Hartman" , "Joel Granados" , "Kees Cook" , "Jan Kara" , "Jan Kara" , linux-s390@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, linux-m68k@lists.linux-m68k.org, linux-serial@vger.kernel.org, "Takashi Iwai" , linux-ext4@vger.kernel.org, "Chuck Lever" , tytso@mit.edu, "Heiko Carstens" , "Vasily Gorbik" , "Alexander Gordeev" , "Christian Borntraeger" In-Reply-To: <20261104-work-procfs-core-v2-19-76ace653a773@kernel.org> References: <20261104-work-procfs-core-v2-0-76ace653a773@kernel.org> <20261104-work-procfs-core-v2-19-76ace653a773@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 05 Nov 2026 19:35:52 +0000 X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > proc_reg_mmap() pins the entry around ->proc_mmap() and that's it. What > the entry hands out lives on without the pin: the vm_operations it put > on the mapping run on every fault, on every write to a read-only page > and on every ptrace access with the entry unpinned, and the mapping > itself survives remove_proc_entry(). For /proc/vmcore that means the > fault handler runs after vmcore_cleanup() freed what it looks at, and a > mapping of the old memory keeps pointing at it after fadump gave that > memory back to the page allocator. /proc/bus/pci has the same problem > when a device goes away. >=20 > So do what kernfs does for the mappings of sysfs files. procfs puts > vm_operations of its own on the mapping. They pin the entry around its > ->open(), ->fault(), ->page_mkwrite() and ->access() and fail with > SIGBUS, or do nothing, once the entry is gone. The entry's > vm_operations are kept in its open node, so every mapping of an entry > [ ... ] > window. >=20 > Entries that are never removed aren't wrapped, procfs never pins them. >=20 > Signed-off-by: Christian Brauner (Amutable) Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261104-work-procf= s-core-v2-0-76ace653a773@kernel.org?part=3D19