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 DB6986071C11 for ; Tue, 3 Nov 2026 15:01:37 +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=CJKVjnH9; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=lB9ymstx 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=1VZl7qidssi1ktD3Tb5xCqeZKKhCHxpcCGjwzNwohWM=; b=CJKVjnH9ZYtGUsXR1G6WdKxU/Y 7LJf6iKlKpy9GaCQz28XScfbpBp4xyQnXrEbNAnwMKbpqF/nVn03YZ7rPXpQ44x7j9D3hxSeOLSvu doHngAeZMnTu4b26b56vXHb0eeF5f9Z4oPt92wdh09KAuPhpAMKbs/G3przuyyKprlbv27wneYync RjTR0XrQetLvvxpuPoa77/DSex0nztCeWWR0ItLOzD5ivstW5+Ln+EP/QnLp1onrbSU+nCLClKoAH dRJJIU5YurN/na9dEBWtuvXjfuHg4DlnD/mkU2dIbvNLabxRLtV0b2i8+Wdn+9JxmnAibXCDnTAyz LT53zYgQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xOG13-00000002pu8-2KNn; Tue, 03 Nov 2026 15:01:37 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xOG12-00000002psE-15Mf for kexec@lists.infradead.org; Tue, 03 Nov 2026 15:01:36 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 09A2943C62; Tue, 3 Nov 2026 15:01:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A97D1F00A15; Tue, 3 Nov 2026 15:01:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793718095; bh=1VZl7qidssi1ktD3Tb5xCqeZKKhCHxpcCGjwzNwohWM=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=lB9ymstxD2jW9FJnjd7yfwgHQCygouVuaUNrPu/PoynIqBUhwdCZzT2zz6hDyMWfw YcZohJmiuou7CXmFeQkBbobxsY7W3rz8baS8GVRJO0kQ8rp7jqpzXBDOF20ZwRkSnG nErT+ShqWAVZWSSCrWbcFrcMc6bjV6OhjCsDbsHj6dNwDTLta4HQXunuCYdd8pGy5N QM0q3S+koNafy+7N3iP/fwwlIqk3Bi1Wb1hFNC1OOvd3tT4xgM2trp03tV1cyoUKB+ JSxbtARnxikJyDqg4WFDJfKyHT4r+mahZr7saUIEqSOy07BNqSd/NKBk4ATzIkxAz4 zi3pQsJaFbcxw== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH RFC 14/16] fs/proc/vmcore: let procfs copy out reads 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: <20261102-work-procfs-core-v1-14-75df35e4f8b8@kernel.org> References: <20261102-work-procfs-core-v1-0-75df35e4f8b8@kernel.org> <20261102-work-procfs-core-v1-14-75df35e4f8b8@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 03 Nov 2026 15:01:33 +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: > Implement ->proc_read_buf() so procfs copies what is read to userspace > after it unpinned the entry. __read_vmcore() fills procfs' buffer > through a kvec iov_iter. So a read goes through that buffer now instead > of straight from the old memory into the reader's, which is what > splice() did already. mmap() isn't affected. On ppc64 a machine check > while reading the old memory used to be recovered through the exception > table of copy_to_user(), by accident. copy_oldmem_page() copies with > _copy_mc_to_iter() now, so a read through procfs' buffer recovers from > it as well. >=20 > The buffer is 128k, which keeps the entry pinned for one such piece at > a time, and /proc/vmcore asks for PROC_ENTRY_FULL_READS so that a > larger read is filled in pieces. kexec-tools treats a short read of it > as fatal. A read that faults on its buffer in a later piece returns the > pieces before it now instead of failing with -EFAULT. fadump removes > /proc/vmcore when its memory is released and that no longer waits for a > reader that faults on its buffer. >=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/20261102-work-procf= s-core-v1-0-75df35e4f8b8@kernel.org?part=3D14