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From: Vasily Averin <vvs@virtuozzo.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
	Christoph Paasch <christoph.paasch@gmail.com>,
	"David S. Miller" <davem@davemloft.net>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	David Ahern <dsahern@kernel.org>,
	Jakub Kicinski <kuba@kernel.org>, netdev <netdev@vger.kernel.org>,
	linux-kernel@vger.kernel.org, kernel@openvz.org,
	Julian Wiedmann <jwi@linux.ibm.com>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Subject: Re: [PATCH net-next v3 RFC] skb_expand_head() adjust skb->truesize incorrectly
Date: Wed, 1 Sep 2021 09:20:27 +0300	[thread overview]
Message-ID: <b653692b-1550-e17a-6c51-894832c56065@virtuozzo.com> (raw)
In-Reply-To: <f4bbce90-f31f-b844-0087-c9d72db06471@gmail.com>

On 8/31/21 10:38 PM, Eric Dumazet wrote:
> On 8/31/21 7:34 AM, Vasily Averin wrote:
>> RFC because it have an extra changes:
>> new is_skb_wmem() helper can be called
>>  - either before pskb_expand_head(), to create skb clones 
>>     for skb with destructors that does not change sk->sk_wmem_alloc
>>  - or after pskb_expand_head(), to change owner in skb_set_owner_w()
>>
>> In current patch I've added both these ways,
>> we need to keep one of them.

If nobody object I vote for 2nd way:

>> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
>> index f931176..3ce33f2 100644
>> --- a/net/core/skbuff.c
>> +++ b/net/core/skbuff.c
>> @@ -1804,30 +1804,47 @@ struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
>>  struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom)
>>  {
... skipped ...
>> -	return skb;
>> +	if (oskb) {
>> +		if (sk)
>> +			skb_set_owner_w(skb, sk);
> 
> Broken for non full sockets.
> Calling skb_set_owner_w(skb, sk) for them is a bug.

I think you're wrong here.
It is 100% equivalent of old code, 
skb_set_owner_w() handles sk_fullsock(sk) inside and does not adjust sk->sk_wmem_alloc.
Please explain if I'm wrong.

>> +		consume_skb(oskb);
>> +	} else if (sk) {
>> +		delta = osize - skb_end_offset(skb);
>> +		if (!is_skb_wmem(skb))
>> +			skb_set_owner_w(skb, sk);
> 
> This would be broken for non full sockets.
> Calling skb_set_owner_w(skb, sk) for them is a bug.
See my comment above.

>> +		skb->truesize += delta;
>> +		if (sk_fullsock(sk))
>> +			refcount_add(delta, &sk->sk_wmem_alloc);
> 
> 
>> +	}	return skb;
Strange line, will fix it.

>>  }
>>  EXPORT_SYMBOL(skb_expand_head);

  reply	other threads:[~2021-09-01  6:20 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1625665132.git.vvs@virtuozzo.com>
2021-07-07 14:04 ` [PATCH IPV6 1/1] ipv6: allocate enough headroom in ip6_finish_output2() Vasily Averin
2021-07-07 14:45   ` David Ahern
2021-07-07 16:42     ` Jakub Kicinski
2021-07-07 17:41       ` Eric Dumazet
2021-07-07 17:53         ` Vasily Averin
2021-07-07 18:30         ` Jakub Kicinski
2021-07-07 18:50           ` Eric Dumazet
2021-07-09  9:04         ` [PATCH IPV6 v2 0/4] " Vasily Averin
2021-07-12  6:44           ` [PATCH IPV6 v3 0/1] " Vasily Averin
     [not found]           ` <cover.1626069562.git.vvs@virtuozzo.com>
2021-07-12  6:45             ` [PATCH IPV6 v3 1/1] " Vasily Averin
2021-07-12 18:30               ` patchwork-bot+netdevbpf
2021-07-13  7:46               ` Vasily Averin
2021-07-13 12:01                 ` [PATCH NET v4 0/1] " Vasily Averin
     [not found]                 ` <cover.1626177047.git.vvs@virtuozzo.com>
2021-07-13 12:01                   ` [PATCH NET v4 1/1] " Vasily Averin
2021-07-18 10:44                     ` Vasily Averin
2021-07-18 15:22                       ` David Ahern
2021-07-18 17:04                       ` David Miller
2021-07-19  7:55                         ` [PATCH NET] ipv6: ip6_finish_output2: set sk into newly allocated nskb Vasily Averin
2021-07-20 10:10                           ` patchwork-bot+netdevbpf
2021-07-13 12:31                 ` [PATCH IPV6 v3 1/1] ipv6: allocate enough headroom in ip6_finish_output2() Vasily Averin
2021-07-12 13:26           ` [PATCH NET 0/7] skbuff: introduce pskb_realloc_headroom() Vasily Averin
     [not found]           ` <cover.1626093470.git.vvs@virtuozzo.com>
2021-07-12 13:26             ` [PATCH NET 1/7] " Vasily Averin
2021-07-12 17:53               ` Jakub Kicinski
2021-07-12 18:45                 ` Vasily Averin
2021-07-13 20:57                   ` [PATCH NET v2 0/7] skbuff: introduce skb_expand_head() Vasily Averin
2021-08-02  8:52                     ` [PATCH NET v3 " Vasily Averin
     [not found]                     ` <cover.1627891754.git.vvs@virtuozzo.com>
2021-08-02  8:52                       ` [PATCH NET v3 1/7] " Vasily Averin
2021-08-02  8:52                       ` [PATCH NET v3 2/7] ipv6: use skb_expand_head in ip6_finish_output2 Vasily Averin
2021-08-02  8:52                       ` [PATCH NET v3 3/7] ipv6: use skb_expand_head in ip6_xmit Vasily Averin
2021-08-02  8:52                       ` [PATCH NET v3 4/7] ipv4: use skb_expand_head in ip_finish_output2 Vasily Averin
2021-08-02  8:52                       ` [PATCH NET v3 5/7] vrf: use skb_expand_head in vrf_finish_output Vasily Averin
2021-08-05 11:55                         ` Julian Wiedmann
2021-08-05 12:55                           ` Vasily Averin
2021-08-06  7:49                           ` [PATCH NET v4 0/7] skbuff: introduce skb_expand_head() Vasily Averin
2021-08-06 10:14                             ` David Miller
2021-08-06 12:53                               ` [PATCH NET] vrf: fix null pointer dereference in vrf_finish_output() Vasily Averin
2021-08-06 22:42                                 ` Jakub Kicinski
2021-08-07  6:41                                   ` Vasily Averin
     [not found]                           ` <cover.1628235065.git.vvs@virtuozzo.com>
2021-08-06  7:49                             ` [PATCH NET v4 1/7] skbuff: introduce skb_expand_head() Vasily Averin
2021-08-06  7:50                             ` [PATCH NET v4 2/7] ipv6: use skb_expand_head in ip6_finish_output2 Vasily Averin
2021-08-06  7:50                             ` [PATCH NET v4 3/7] ipv6: use skb_expand_head in ip6_xmit Vasily Averin
     [not found]                               ` <CALMXkpaay1y=0tkbnskr4gf-HTMjJJsVryh4Prnej_ws-hJvBg@mail.gmail.com>
2021-08-20 22:44                                 ` Christoph Paasch
2021-08-21  6:21                                   ` Vasily Averin
2021-08-22 17:04                                     ` Christoph Paasch
2021-08-22 17:13                                       ` Christoph Paasch
2021-08-23  5:44                                         ` Vasily Averin
2021-08-23  5:59                                           ` Vasily Averin
2021-08-23  7:56                                             ` [PATCH NET-NEXT] ipv6: skb_expand_head() adjust skb->truesize incorrectly Vasily Averin
2021-08-23 17:25                                               ` Christoph Paasch
2021-08-23 21:45                                                 ` Eric Dumazet
2021-08-23 21:51                                                   ` Eric Dumazet
2021-08-23 22:23                                                     ` Eric Dumazet
2021-08-24  8:50                                                       ` Vasily Averin
2021-08-24 17:21                                                         ` Vasily Averin
2021-08-25 17:49                                                           ` Christoph Paasch
2021-08-29 12:59                                                             ` [PATCH v2] " Vasily Averin
2021-08-30  5:52                                                               ` [PATCH net-next " Vasily Averin
2021-08-30 16:01                                                               ` [PATCH " Eric Dumazet
2021-08-30 18:09                                                                 ` Vasily Averin
2021-08-30 18:37                                                                   ` Vasily Averin
2021-08-30 19:58                                                                   ` Eric Dumazet
2021-08-31 14:34                                                                     ` [PATCH net-next v3 RFC] " Vasily Averin
2021-08-31 19:38                                                                       ` Eric Dumazet
2021-09-01  6:20                                                                         ` Vasily Averin [this message]
2021-09-01  8:11                                                                           ` [PATCH net-next v4] " Vasily Averin
2021-09-01 16:58                                                                             ` Christoph Paasch
2021-09-01 19:17                                                                             ` Eric Dumazet
2021-09-02  3:59                                                                               ` Vasily Averin
2021-09-02  4:32                                                                                 ` Eric Dumazet
2021-09-02  4:48                                                                                   ` Eric Dumazet
2021-09-02  7:13                                                                                     ` Vasily Averin
2021-09-02  7:33                                                                                       ` Vasily Averin
2021-09-02  8:31                                                                                         ` Vasily Averin
2021-09-02 11:12                                                                                           ` [PATCH net-next v5] " Vasily Averin
2021-09-02 15:53                                                                                             ` Christoph Paasch
2021-09-02 16:32                                                                                               ` Vasily Averin
2021-09-06 18:01                                                                                                 ` [PATCH net v6] " Vasily Averin
2021-09-06 18:03                                                                                                   ` Vasily Averin
2021-08-27 15:23                                                       ` [PATCH NET-NEXT] ipv6: " Vasily Averin
2021-08-27 16:47                                                         ` Eric Dumazet
2021-08-28  8:01                                                           ` Vasily Averin
2021-08-06  7:50                             ` [PATCH NET v4 4/7] ipv4: use skb_expand_head in ip_finish_output2 Vasily Averin
2021-08-06  7:50                             ` [PATCH NET v4 5/7] vrf: use skb_expand_head in vrf_finish_output Vasily Averin
2021-08-06  7:50                             ` [PATCH NET v4 6/7] ax25: use skb_expand_head Vasily Averin
2021-08-06  7:50                             ` [PATCH NET v4 7/7] bpf: use skb_expand_head in bpf_out_neigh_v4/6 Vasily Averin
2021-08-02  8:52                       ` [PATCH NET v3 6/7] ax25: use skb_expand_head Vasily Averin
2021-08-02  8:52                       ` [PATCH NET v3 7/7] bpf: use skb_expand_head in bpf_out_neigh_v4/6 Vasily Averin
     [not found]                   ` <cover.1626206993.git.vvs@virtuozzo.com>
2021-07-13 20:57                     ` [PATCH NET v2 1/7] skbuff: introduce skb_expand_head() Vasily Averin
2021-07-13 20:58                     ` [PATCH NET v2 2/7] ipv6: use skb_expand_head in ip6_finish_output2 Vasily Averin
2021-07-13 20:58                     ` [PATCH NET v2 3/7] ipv6: use skb_expand_head in ip6_xmit Vasily Averin
2021-07-13 20:58                     ` [PATCH NET v2 4/7] ipv4: use skb_expand_head in ip_finish_output2 Vasily Averin
2021-07-13 20:58                     ` [PATCH NET v2 5/7] vrf: use skb_expand_head in vrf_finish_output Vasily Averin
2021-07-13 20:58                     ` [PATCH NET v2 6/7] ax25: use skb_expand_head Vasily Averin
2021-07-13 20:58                     ` [PATCH NET v2 7/7] bpf: use skb_expand_head in bpf_out_neigh_v4/6 Vasily Averin
2021-07-12 13:26             ` [PATCH NET 2/7] ipv6: use pskb_realloc_headroom in ip6_finish_output2 Vasily Averin
2021-07-12 13:26             ` [PATCH NET 3/7] ipv6: use pskb_realloc_headroom in ip6_xmit refactoring Vasily Averin
2021-07-12 13:27             ` [PATCH NET 4/7] ipv4: use pskb_realloc_headroom in ip_finish_output2 Vasily Averin
2021-07-12 13:27             ` [PATCH NET 5/7] vrf: use pskb_realloc_headroom in vrf_finish_output Vasily Averin
2021-07-12 13:27             ` [PATCH NET 6/7] ax25: use pskb_realloc_headroom Vasily Averin
2021-07-12 13:27             ` [PATCH NET 7/7] bpf: use pskb_realloc_headroom in bpf_out_neigh_v4/6 Vasily Averin
     [not found]         ` <cover.1625818825.git.vvs@virtuozzo.com>
2021-07-09  9:04           ` [PATCH IPV6 v2 1/4] ipv6: allocate enough headroom in ip6_finish_output2() Vasily Averin
2021-07-09 17:58             ` David Miller
2021-07-10  2:53               ` Vasily Averin
2021-07-09  9:04           ` [PATCH IPV6 v2 2/4] ipv6: use new helper skb_expand_head() in ip6_xmit() Vasily Averin
2021-07-09  9:05           ` [PATCH IPV6 v2 3/4] ipv6: ip6_finish_output2 refactoring Vasily Averin
2021-07-09  9:05           ` [PATCH IPV6 v2 4/4] ipv6: ip6_xmit refactoring Vasily Averin

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