From 479f5547239d970d3833f15f54a6481fffdb91ec Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Mon, 31 Jan 2022 22:52:54 -0800
Subject: tcp: fix mem under-charging with zerocopy sendmsg()
We got reports of following warning in inet_sock_destruct()
WARN_ON(sk_forward_alloc_get(sk));
Whenever we add a non zero-copy fragment to a pure zerocopy skb,
we have to anticipate that whole skb->truesize will be uncharged
when skb is finally freed.
skb->data_len is the payload length. But the memory truesize
estimated by __zerocopy_sg_from_iter() is page aligned.
Fixes: 9b65b17db723 ("net: avoid double accounting for pure zerocopy skbs")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Talal Ahmad <talalahmad@google.com>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Link: https://lore.kernel.org/r/20220201065254.680532-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
net/ipv4/tcp.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
(limited to 'net/ipv4/tcp.c')
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 78e81465f5f3..bdf108f544a4 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1322,10 +1322,13 @@ new_segment:
/* skb changing from pure zc to mixed, must charge zc */
if (unlikely(skb_zcopy_pure(skb))) {
- if (!sk_wmem_schedule(sk, skb->data_len))
+ u32 extra = skb->truesize -
+ SKB_TRUESIZE(skb_end_offset(skb));
+
+ if (!sk_wmem_schedule(sk, extra))
goto wait_for_space;
- sk_mem_charge(sk, skb->data_len);
+ sk_mem_charge(sk, extra);
skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY;
}
--
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