Re: [PATCH] net: use __GFP_NORETRY for high order allocations

David Miller [off-list ref] writes:

From: Eric Dumazet <redacted>
Date: Thu, 06 Feb 2014 10:42:42 -0800

quoted

From: Eric Dumazet <edumazet@google.com>

sock_alloc_send_pskb() & sk_page_frag_refill()
have a loop trying high order allocations to prepare
skb with low number of fragments as this increases performance.

Problem is that under memory pressure/fragmentation, this can
trigger OOM while the intent was only to try the high order
allocations, then fallback to order-0 allocations.

We had various reports from unexpected regressions.

According to David, setting __GFP_NORETRY should be fine,
as the asynchronous compaction is still enabled, and this
will prevent OOM from kicking as in :

 ...

quoted

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: David Rientjes <rientjes@google.com>

Applied, do we want this for -stable?

The first hunk goes back to 3.12 and the second hunk goes back to 3.8.

I think so.    The change is safe and this class of problem can cause an
external attack to trigger an OOM on your box, by controlling the packet
flow.

Eric