Re: [PATCH net-next] myri10ge: fix truesize underestimation

On 10/20/11 16:59, Eric Dumazet wrote:

Le jeudi 20 octobre 2011 à 16:45 -0400, Andrew Gallatin a écrit :

quoted

On 10/20/11 16:44, Eric Dumazet wrote:

quoted

Le jeudi 20 octobre 2011 à 15:33 -0500, Jon Mason a écrit :

quoted

On Thu, Oct 20, 2011 at 3:10 PM, Eric Dumazet[off-list ref]   wrote:

quoted

skb->truesize must account for allocated memory, not the used part of
it. Doing this work is important to avoid unexpected OOM situations.

Signed-off-by: Eric Dumazet<redacted>

Acked-by: Jon Mason<redacted>

Thanks for reviewing Jon !

Please wait a second..  I think the patch is incorrect.

There is already code in myri10ge_rx_skb_build() which
attempts to set the truesize.  However, it sets it to
the used, rather than the allocated size so it is apparently
incorrect.

I'd prefer we fix that code.

Well, I believe I did exactly that :)

truesize of initial skb is fine.

Then for everay frag added, you must add to skb-truesize the allocated
memory for this frag.

You add frags of a given size (small or big)

In the end, its truesize += bytes * number_of_frags

(bytes being small_size or big_size)

OK, I'm feeling foolish.  I somehow missed the first hunk
of your patch (some local change made it not apply cleanly, and
I did not notice that).

Yes, your patch is correct.  Sorry for the hassle!


Acked-by: Andrew Gallatin <redacted>