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

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Message-ID: <YxBwAANmAAivHYA5@dhcp22.suse.cz>
Date:   Thu, 1 Sep 2022 10:40:32 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Oscar Salvador <osalvador@...e.de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Vlastimil Babka <vbabka@...e.cz>,
        Eric Dumazet <edumazet@...gle.com>,
        Waiman Long <longman@...hat.com>,
        Suren Baghdasaryan <surenb@...gle.com>
Subject: Re: [PATCH 3/3] mm,page_owner: Filter out stacks by a threshold
 counter

On Thu 01-09-22 06:42:49, Oscar Salvador wrote:
[...]
> +static ssize_t read_page_owner_threshold(struct file *file, char __user *buf,
> +					 size_t count, loff_t *pos)
> +{
> +	char *kbuf;
> +	int ret = 0;
> +
> +	count = min_t(size_t, count, PAGE_SIZE);
> +
> +	if (*pos >= count)
> +		return 0;
> +
> +	kbuf = kmalloc(count, GFP_KERNEL);

No, you do not want to trigger user defined allocation like that. I
would use seq_file.
-- 
Michal Hocko
SUSE Labs