linux-kernel - Re: [PATCH] tun: avoid high-order page allocation for packet header

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Message-ID: <20230731135854.3628918b@kernel.org>
Date:   Mon, 31 Jul 2023 13:58:54 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Tahsin Erdogan <trdgn@...zon.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tun: avoid high-order page allocation for packet header

On Tue, 25 Jul 2023 20:09:36 -0700 Tahsin Erdogan wrote:
> @@ -1838,6 +1838,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
>  			 */
>  			zerocopy = false;
>  		} else {
> +			if (linear == 0)
> +				linear = min_t(size_t, good_linear, copylen);

nit: would you mind changing to !linear instead of linear == 0 ?

Also - I don't see linear explicitly getting set to 0. What guarantees
that? What's the story there?

Otherwise seems reasonable. One more allocation but hopefully nobody
will notice.
-- 
pw-bot: cr