From 479f5547239d970d3833f15f54a6481fffdb91ec Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 31 Jan 2022 22:52:54 -0800 Subject: [PATCH] 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 Cc: Talal Ahmad Cc: Arjun Roy Cc: Willem de Bruijn Acked-by: Soheil Hassas Yeganeh Link: https://lore.kernel.org/r/20220201065254.680532-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski --- net/ipv4/tcp.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) 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; } -- 2.11.0