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=1793907350; b=GHCE7KbAh0h5eIhaHGM0OiNeIGhSeFz3E7KrNWuMer16fGeh9rQnWqtNW68VzoYQvPT/ sDMxCRn9VrbTfk5lcD/NdhK8YPNMy1IIbKcETwwkWgX484OvUcTqKHyf+5XwTZ6Jm/GrK i51mWx2AR9EdAIEEq1DKzWfFE7szIWIipGEtyRIaLHE33zuBsHLgSZUMv7+5mGjdZogz1 NsG84nVQnl5O25XsuD79P0j4oml3aRGQEUciZcIDkQiPfxH2kVayyGOL6U7tb/nJwujh3 zTtjvMUlNAxq2zmMdPUoBKOX/m+aL1XznQcnaHOM+q8wngV7wA8+6iJXKUXi9EAKdNw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793907350; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=AmN7iDpzjJ1PM6HacIbA4oMAV9jT2VXf3oFN7TUN1kQ=; b=rkPY+2A79rpLZL2cF3vHl3/4/2D0kmQ3W3WjTkdPmqUrE0p78sSCnZ5Px/Pb0DCjplax FkLjH2l8TDF30yUcHhT/z3hugurChTGZIil5HZCNuvaZYwjaWvnhUQg/24TxYt26toSXp 18BUI3NXh01lpb0TfZGPVbof9ha6SJNRVkyLwvpul5Xr96Qo98Dc+JRRUiKfLVThNV+d9 BYWzIhlQ5HrdB2Nid8ezQ4f782A7QQjrEnFIUSgr/ztPOl2/YUxmVf9Ouh6THPOWeoL6r EEuVvuYFh4BIqd9yFYPJmXGJ0oAbUAfRZDwuD6WFvkhdPO5xpfii7ec2BGW+k/agVeQ== 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=F2b0FoPl; 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 816B76079C0B; Thu, 5 Nov 2026 19:35:50 +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=F2b0FoPl Received: by smtp.kernel.org (Postfix) with ESMTPSA id A4C061F0089E; Thu, 5 Nov 2026 19:35:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793907350; bh=AmN7iDpzjJ1PM6HacIbA4oMAV9jT2VXf3oFN7TUN1kQ=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=F2b0FoPlGpVNh9mR9X4mwXarD/KuCYBVnvUmH6E7tZhJtBt5PCXx933IV6aiReouK LnK4sp79dqsWsQgIRBB52e6C2scR+7O9aq42OmuiMuAhSvxgt8qaQEjRMxcJps+5xW VdeI/08WnjHl5IfcKYrPNVcCkskBx+YzqyRBgsiWHP62+S9vXdFt+dSnKmNPdL54Gi Fu1iRVyhor6sLsyNi3KpdJnVwZfldWCmfqPHKyXacsYeRvCGc5d0g5zBMwG5Z1zMa4 riwDW9+fwdB3AHVr9RxmUYb4iBKW9d+rhmsuBt5B7UD8oM7aTO9IwB8MyCJWnccLPv tGGpP6SDL1kpA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH RESEND v2 17/23] fs/proc/vmcore: let procfs copy out reads 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-v2-17-76ace653a773@kernel.org> References: <20261104-work-procfs-core-v2-0-76ace653a773@kernel.org> <20261104-work-procfs-core-v2-17-76ace653a773@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 05 Nov 2026 19:35:48 +0000 X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > 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/20261104-work-procf= s-core-v2-0-76ace653a773@kernel.org?part=3D17