From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1DD96606A31B for ; Thu, 5 Nov 2026 20:21:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=VtmSmGEI; 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 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Reply-To:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Date: Content-Transfer-Encoding:Content-Type:References:In-Reply-To:Cc:To:Subject: From:Message-ID:MIME-Version:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=Uq4i262WOQaYVL9uHrrjKQ33JdfPWVKPdUraeND3OfE=; b=VtmSmGEIsyAM0rzZvTAhJFH4IZ HLIJTASjFPBW7w05xgwtdYumOPdRQnLLyRbiboy5aIUnhUG7aPHQ7FFp/ZTRmDpQNUg/CPW56D0jz iGIV1OuXpCvQOgnIZhN/M19JDByB66bmVZu18StJDPHEVJh2S3zs9Z59SnhwsZFh7FoX05ANErx8E hnNtFNmSPRkXfNYPVCzvHcEYqbOm0sjpZAyGiCgoNlpOpEvU5MObL1sIuHFYxJO4GSR7Y5r5fuyVB gPiAyt/mT1dxpuIX1IM026rHa2DEYEzdAKIKnY48Y6xsZMVOl3j4n7jD2YkIvruD3uHSOB8DEVyBx V1SuyeWA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xP3HX-0000000ANkU-0ALs; Thu, 05 Nov 2026 19:37:55 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xP3Fb-0000000AN5C-2Y2e for kexec@lists.infradead.org; Thu, 05 Nov 2026 19:36:00 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 115C9601AC; Thu, 5 Nov 2026 19:35:55 +0000 (UTC) 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 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-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Sender: "kexec" X-Spam-Status: No, score=-10.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: > 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