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

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Message-ID: <YxXlQWy8LLEy6rcD@dhcp22.suse.cz>
Date:   Mon, 5 Sep 2022 14:02:09 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Ammar Faizi <ammarfaizi2@...weeb.org>
Cc:     Oscar Salvador <osalvador@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Memory Management Mailing List <linux-mm@...ck.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Eric Dumazet <edumazet@...gle.com>,
        Waiman Long <longman@...hat.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Alexander Potapenko <glider@...gle.com>
Subject: Re: [PATCH v2 3/3] mm,page_owner: Filter out stacks by a threshold
 counter

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