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Date:   Thu, 1 Sep 2022 10:40:32 +0200
From:   Michal Hocko <mhocko@suse.com>
To:     Oscar Salvador <osalvador@suse.de>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Vlastimil Babka <vbabka@suse.cz>,
        Eric Dumazet <edumazet@google.com>,
        Waiman Long <longman@redhat.com>,
        Suren Baghdasaryan <surenb@google.com>
Subject: Re: [PATCH 3/3] mm,page_owner: Filter out stacks by a threshold
 counter
Message-ID: <YxBwAANmAAivHYA5@dhcp22.suse.cz>
References: <20220901044249.4624-1-osalvador@suse.de>
 <20220901044249.4624-4-osalvador@suse.de>
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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