Re: [PATCH v2 3/3] mm,page_owner: Filter out stacks by a threshold counter

From: Michal Hocko <mhocko@suse.com>
To: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Cc: Oscar Salvador <osalvador@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Memory Management Mailing List <linux-mm@kvack.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Eric Dumazet <edumazet@google.com>,
	Waiman Long <longman@redhat.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Marco Elver <elver@google.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Alexander Potapenko <glider@google.com>
Subject: Re: [PATCH v2 3/3] mm,page_owner: Filter out stacks by a threshold counter
Date: Mon, 5 Sep 2022 14:02:09 +0200	[thread overview]
Message-ID: <YxXlQWy8LLEy6rcD@dhcp22.suse.cz> (raw)
In-Reply-To: <20220905115459.567583-1-ammarfaizi2@gnuweeb.org>

On Mon 05-09-22 18:54:59, Ammar Faizi wrote:
> On Mon, 5 Sep 2022 13:31:02 +0200, Michal Hocko wrote:
[...]
> > > static ssize_t write_page_owner_threshold(struct file *file, const char __user *buf,
> > > 					  size_t count, loff_t *pos)
> > > {
> > > 	char kbuf[21];
> > > 	int ret;
> > > 
> > > 	count = min_t(size_t, count, sizeof(kbuf));
> > > 	if (copy_from_user(kbuf, buf, count))
> > > 		return -EFAULT;
> > > 
> > > 	kbuf[count - 1] = '\0';
> > > 	ret = kstrtoul(kbuf, 10, &threshold);
> > > 	return ret ? ret : count;
> > > }
> > 
> > Isn't there a proc_dointvec counterpart for debugfs?
> 
> Ah, well. If that's much simpler, we should go with that. I am not
> familiar proc_dointvec() interface, so I couldn't say about it.

Just to clarify. proc_dointvec is rather specific to proc/sysctl
interface. I was too lazy to look whether debugfs has something similar
available. Maybe writing to debugfs is not all that common but I would
expect a shared code to write a simple value would be there.

-- 
Michal Hocko
SUSE Labs