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 623EE199234 for ; Mon, 24 Nov 2025 17:27:03 +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=1764005223; cv=none; b=cEfXeKX4DDoJGubx32nRsqu+3yeSwSaUSv9qeJ9lK6wDS19IwY/YXj5kmPT5otJojwORsGYyxWGBcLFZI2HMYl06aCyrEca4Xci6lHEoRaOE4szi1PNuF027tHchKUcmG1B7YvbLSEvXzxBO4aMtqnhrXNzdyXtPgnf2vD100rk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764005223; c=relaxed/simple; bh=GMdw4gCtYdZY/qUPfitYGRYtROmXzLy15e4nwdtEyFQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pnOXdxaBLSxr+0MP6K42dJDrs4eoIrGPO3+VrUx519cYSAfNEBEHQ79SMGLN9rxA05GIgw1AMCjMcGujyotvkDVIExCsDGcziggqXbv0iF33w7Kd5LbBwmrcrpJ5FmtMIedr0jgwJdAi9z4Oe+0C0tbXvQz5qioaZs4H7G7qBn8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aN4dbhoJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aN4dbhoJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90E74C4CEF1; Mon, 24 Nov 2025 17:27:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764005222; bh=GMdw4gCtYdZY/qUPfitYGRYtROmXzLy15e4nwdtEyFQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aN4dbhoJBvu5fejbJ7fmJ+L9OvIazTZb8XFCHOjy2/vdBAvUhEk1m3j/SdgzbPRe8 QI9/D9lgiLa1es149LOiMTfvS6COT0lJLp5mw1he4IGAH3gslTi/4YBjg2Knm+DyKD NXvxvjd0aWpaHOt7C+26I6A/JKFqtVtE0gaEdXWA= Date: Mon, 24 Nov 2025 18:27:00 +0100 From: Greg KH To: jane.chu@oracle.com Cc: tj@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] fs/kernfs: raise sb->maxbytes to MAX_LFS_FILESIZE Message-ID: <2025112410-shingle-wackiness-d25c@gregkh> References: <20251111202606.1505437-1-jane.chu@oracle.com> <2025112410-carnivore-anemia-e6eb@gregkh> 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-Disposition: inline In-Reply-To: On Mon, Nov 24, 2025 at 09:06:21AM -0800, jane.chu@oracle.com wrote: > Hi, Greg, > > On 11/24/2025 8:17 AM, Greg KH wrote: > > On Tue, Nov 11, 2025 at 01:26:06PM -0700, Jane Chu wrote: > > > On an ARM64 A1 system, it's possible to have physical memory span > > > up to the 64T boundary, like below > > > > > > $ lsmem -b -r -n -o range,size > > > 0x0000000080000000-0x00000000bfffffff 1073741824 > > > 0x0000080000000000-0x000008007fffffff 2147483648 > > > 0x00000800c0000000-0x0000087fffffffff 546534588416 > > > 0x0000400000000000-0x00004000bfffffff 3221225472 > > > 0x0000400100000000-0x0000407fffffffff 545460846592 > > > > > > So it's time to extend /sys/kernel/mm/page_idle/bitmap to be able > > > to account for >2G number of pages, by raising the kernfs file size > > > limit. > > > > Wait, we are having sysfs files that are bigger than >2G? Which files > > exactly? > > This file: /sys/kernel/mm/page_idle/bitmap > that tracks idle pages, 1 bit per page. Why is that a sysfs file and not a debugfs file? > Because of the above memory span, so even though the system has < 64TiB > memory, we still need to be able to seek beyond the 2GiB point in the > /sys/kernel/mm/page_idle/bitmap file. What uses this file? It's not on my systems, what arch uses it? thanks, greg k-h