[PATCH net] net: do not delay zero-copy skbs in skb_attempt_defer_free()

[PATCH net] net: do not delay zero-copy skbs in skb_attempt_defer_free()

[Eric Dumazet]

After the blamed commit, TCP tx zero copy notifications could be
arbitrarily delayed and cause regressions in applications waiting
for them.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: e20dfbad8aab ("net: fix napi_consume_skb() with alien skbs")
---
 net/core/skbuff.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 699c401a5eae9c497a42b6bdd8593af7890529f4..dc47d3efc72ed86dce5e382d505eda7bc863669a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -7266,10 +7266,15 @@ void skb_attempt_defer_free(struct sk_buff *skb)
 {
 	struct skb_defer_node *sdn;
 	unsigned long defer_count;
-	int cpu = skb->alloc_cpu;
 	unsigned int defer_max;
 	bool kick;
+	int cpu;
 
+	/* zero copy notifications should not be delayed. */
+	if (skb_zcopy(skb))
+		goto nodefer;
+
+	cpu = skb->alloc_cpu;
 	if (cpu == raw_smp_processor_id() ||
 	    WARN_ON_ONCE(cpu >= nr_cpu_ids) ||
 	    !cpu_online(cpu)) {
-- 
2.53.0.310.g728cabbaf7-goog

Re: [PATCH net] net: do not delay zero-copy skbs in skb_attempt_defer_free()

[Jason Xing]

On Tue, Feb 17, 2026 at 3:37 AM Eric Dumazet <edumazet@google.com> wrote:
>
> After the blamed commit, TCP tx zero copy notifications could be
> arbitrarily delayed and cause regressions in applications waiting
> for them.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Fixes: e20dfbad8aab ("net: fix napi_consume_skb() with alien skbs")

Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>

Thanks!

Re: [PATCH net] net: do not delay zero-copy skbs in skb_attempt_defer_free()

[Willem de Bruijn]

Eric Dumazet wrote:
> After the blamed commit, TCP tx zero copy notifications could be
> arbitrarily delayed and cause regressions in applications waiting
> for them.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Fixes: e20dfbad8aab ("net: fix napi_consume_skb() with alien skbs")

Reviewed-by: Willem de Bruijn <willemb@google.com>

Re: [PATCH net] net: do not delay zero-copy skbs in skb_attempt_defer_free()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 16 Feb 2026 19:36:53 +0000 you wrote:
> After the blamed commit, TCP tx zero copy notifications could be
> arbitrarily delayed and cause regressions in applications waiting
> for them.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Fixes: e20dfbad8aab ("net: fix napi_consume_skb() with alien skbs")
> 
> [...]

Here is the summary with links:
  - [net] net: do not delay zero-copy skbs in skb_attempt_defer_free()
    https://git.kernel.org/netdev/net/c/0943404b1f3b

You are awesome, thank you!
-- 
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