Re: [PATCH net-next] ip: avoid OOM kills with large UDP sends over loopback

On 6/22/21 7:19 PM, Jakub Kicinski wrote:

On Tue, 22 Jun 2021 09:54:22 -0700 Jakub Kicinski wrote:

quoted

quoted

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+static inline void sk_allocation_push(struct sock *sk, gfp_t flag, gfp_t *old)
+{
+	*old = sk->sk_allocation;
+	sk->sk_allocation |= flag;
+}
+    

This is not thread safe.

Remember UDP sendmsg() does not lock the socket for non-corking sends.  

Ugh, you're right :(

Hm, isn't it buggy to call sock_alloc_send_[p]skb() without holding the
lock in the first place, then? The knee jerk fix would be to add another 
layer of specialization to the helpers:

It is not buggy. Please elaborate if you found it is.