From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B454614883F for ; Mon, 21 Apr 2025 18:26:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745260011; cv=none; b=JOrcYaT3+jE+Qgff8Dmf6l4awcSJfKwr2n+jEIJBhoGXH9uM1XgUvV+t6t2BAoBTKFqm7gTkBnRxYPy86OsxGHLdyFkM0gQrEjQXujjQP6blSePECxCHSIWAse8muJTxDbL7hMKOxmiREkxTEz87hfodNm0EitQNIflqpZmiIkg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745260011; c=relaxed/simple; bh=abb8lHtjBmp/3FXlq9AafpfoQuPpkv881qkgqjb9Rsk=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=CIQaeIWL1M9XmKTlWKFKxkUJ4ssKDYAdC8cu3SSvmTvjdFlqqt5QglY+VfRTWSWJKyk4HWHVIl0F0y1zzhk0GyT09ml0Wxn2T5Y6oxE2pNZzCTiW1VmgfIqkZO0RBWknfH3tjZJZthyEiRbQZbwxU8ZvX6Pi4lFpw2noTkHWuEs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=PPguWuDx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="PPguWuDx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF368C4CEE4; Mon, 21 Apr 2025 18:26:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1745260011; bh=abb8lHtjBmp/3FXlq9AafpfoQuPpkv881qkgqjb9Rsk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=PPguWuDxV90WFW4FyKTJraT08uHhvn0/gt+Plk+13SLUmCX7/Oc9r6Zj7Z2tT4IK1 hraku9eA24FpFJw9I6qP+3wMZIcWV21rux5ALfze4LNKVTQisK725WzSnPy2rzCr0b 55ifH/89+CEiDxP+pjauFr8TcBnlUKGKuha7TaQA= Date: Mon, 21 Apr 2025 11:26:50 -0700 From: Andrew Morton To: Mike Rapoport Cc: Ruihan Li , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/mm_init: Don't iterate pages below ARCH_PFN_OFFSET Message-Id: <20250421112650.4fe689205944ccdaf078ca28@linux-foundation.org> In-Reply-To: References: <20250419122801.1752234-1-lrh2000@pku.edu.cn> <20250420135709.732883ee775ad8b41fb668ca@linux-foundation.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit On Mon, 21 Apr 2025 19:35:25 +0300 Mike Rapoport wrote: > On Sun, Apr 20, 2025 at 01:57:09PM -0700, Andrew Morton wrote: > > On Sat, 19 Apr 2025 20:28:01 +0800 Ruihan Li wrote: > > > > > If ARCH_PFN_OFFSET is very large (e.g., something like 2^64-2GiB if the > > > kernel is used as a library and loaded at a very high address), the > > > pointless iteration for pages below ARCH_PFN_OFFSET will take a very > > > long time, and the kernel will look stuck at boot time. > > > > > > This commit sets the initial value of pfn_hole to ARCH_PFN_OFFSET, which > > > avoids the problematic and useless iteration mentioned above. > > > > > > This problem has existed since commit 907ec5fca3dc ("mm: zero remaining > > > unavailable struct pages"). > > > > > > Signed-off-by: Ruihan Li > > > --- > > > Link to v1: > > > - https://lore.kernel.org/linux-mm/20250418162727.1535335-1-lrh2000@pku.edu.cn/ > > > Changes since v1: > > > - Removed the unnecessary Fixes tag. > > > > Why was the Fixes: considered unnecessary? It seems to be useful > > information? > > I didn't think it was important enough for AUTOSEL to pick it. They've been asked not to backport MM patches unless they have an explicit cc:stable.