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 78733302CD5
	for <linux-kernel@vger.kernel.org>; Tue, 28 Apr 2026 14:16:41 +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=1777385801; cv=none; b=Hy1oz1QVuE4HhzUBtk6//eaO5uzFdbPMeB+zgcgxsRO3YpVvi5PtWgVc8ZoUGwoqThnd8xnBPVte04xFD0VCXKfTG8vHYlbNY/cYnIld6uzisyXEBX8ownGL3Js8kepvEnmYY9S5EHP/tGCLRXJiBhmzg500AlvkbSjMc6GzM8U=
ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org;
	s=arc-20240116; t=1777385801; c=relaxed/simple;
	bh=UattL/at57T5QqsU15Ijo7r8+bjYkLs0PoPIsDETnyk=;
	h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References:
	 Mime-Version:Content-Type; b=eLYQXp6POpIIssyzDgyVttKLu86ja7qZKYrt4YPQBCZEyWPcns0X7NLtDoGvGK0ofq4Q4+mYEZWWK7bLtuHChwY/IuGvdYPyZrWV90bA07Rpb/MQxaPTkZ2AGy3Rem16u/FLmEArsz2MSXlYJPd4e+WItiAT8UOVRmhG2Ts+J7s=
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=Y91yBWuL; 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="Y91yBWuL"
Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8300AC2BCB5;
	Tue, 28 Apr 2026 14:16:40 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org;
	s=korg; t=1777385800;
	bh=UattL/at57T5QqsU15Ijo7r8+bjYkLs0PoPIsDETnyk=;
	h=Date:From:To:Cc:Subject:In-Reply-To:References:From;
	b=Y91yBWuLlrROcgwR1CTvATWhhqa90vwmQzmigqGiL+94Xm2XlEyTabW11nUbxAsNM
	 dJuk4dC12lxZhh9RDrcEPsGUO0Q7lTOOpsm8kNfGJO27C+8CMMIIfTiQeb63nv5N4j
	 JF6DhqVGbIXv+3h2fKMZ1/54crN8gvbW2te4TSKg=
Date: Tue, 28 Apr 2026 07:16:40 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Zhen Ni <zhen.ni@easystack.cn>
Cc: vbabka@kernel.org, surenb@google.com, mhocko@suse.com,
 jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com,
 linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 3/4] mm/page_owner: add NUMA node filter with
 nodelist support
Message-Id: <20260428071640.53b6f37e3a0b2d0ce520622e@linux-foundation.org>
In-Reply-To: <20260428071112.1420380-4-zhen.ni@easystack.cn>
References: <20260428071112.1420380-1-zhen.ni@easystack.cn>
	<20260428071112.1420380-4-zhen.ni@easystack.cn>
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: <linux-kernel.vger.kernel.org>
List-Subscribe: <mailto:linux-kernel+subscribe@vger.kernel.org>
List-Unsubscribe: <mailto:linux-kernel+unsubscribe@vger.kernel.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit

On Tue, 28 Apr 2026 15:11:11 +0800 Zhen Ni <zhen.ni@easystack.cn> wrote:

> Add NUMA node filtering functionality to page_owner to allow
> filtering pages by specific NUMA node(s) using nodelist format.
> 
> The filter allows users to focus on pages from specific NUMA nodes,
> which is useful for NUMA-aware memory allocation analysis and debugging.
> 
> Supported input formats:
> - Single node: echo "2" > nid
> - Multiple nodes: echo "0,2,3" > nid
> - Node range: echo "0-3" > nid
> - Mixed format: echo "0,2-4,7" > nid
> - Disable filter: echo "-1" > nid
> 
> ...
>
> +static ssize_t nid_filter_write(struct file *file,
> +				 const char __user *buf,
> +				 size_t count, loff_t *ppos)
> +{
> +	char *kbuf;
> +	nodemask_t mask;
> +	int ret;
> +	int val;
> +
> +	/*
> +	 * Limit input size to handle worst-case nodelist (all nodes).
> +	 * Worst case per node: ",NNNNN" (comma + 5-digit node number) = 6 bytes.
> +	 * Formula: 100 bytes overhead + 6 * MAX_NUMNODES
> +	 */
> +	if (count > (100 + 6 * MAX_NUMNODES))
> +		return -EINVAL;
> +
> +	kbuf = kmalloc(count + 1, GFP_KERNEL);
> +	if (!kbuf)
> +		return -ENOMEM;
> +
> +	if (copy_from_user(kbuf, buf, count)) {
> +		ret = -EFAULT;
> +		goto out_free;
> +	}
> +	kbuf[count] = '\0';

strncpy_from_user() was not useful here?

> +	/* Support: "-1" to clear, or nodelist format like "0", "0,2", "0-3" */
> +	if (kstrtoint(kbuf, 10, &val) == 0 && val == -1)
> +		nodes_clear(mask);
> +	else if (nodelist_parse(kbuf, mask)) {
> +		ret = -EINVAL;
> +		goto out_free;
> +	}
> +
> +	owner_filter.nid_mask = mask;
> +	ret = count;
> +
> +out_free:
> +	kfree(kbuf);
> +	return ret;
> +}