From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D410EC433EF for ; Thu, 16 Sep 2021 14:53:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A7FAB61246 for ; Thu, 16 Sep 2021 14:53:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238929AbhIPOys (ORCPT ); Thu, 16 Sep 2021 10:54:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58972 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231793AbhIPOyr (ORCPT ); Thu, 16 Sep 2021 10:54:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631804006; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5X1WyxGzxFyqToUNiUfnMNvJRCer2A9Q1/BuNT4BZq0=; b=CUAN0fhYADBmX2Fw4iIWSU40YocCwvDP5foaDEXSE+jGVK1MNBIda3Z8lFWINBXs+ivXsW f6mRi9WH9d5FT1noAhzsX6fgBHfc+3BOXIBSTwB5UQzBjFntQe9PmOkxgJUYCyY7kN9d/H C9p2aPVfs8j4lfvV7/9otThldpFgEfY= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-279-EhUHRJMTOj2N8Hx7PVd9qw-1; Thu, 16 Sep 2021 10:53:25 -0400 X-MC-Unique: EhUHRJMTOj2N8Hx7PVd9qw-1 Received: by mail-wr1-f70.google.com with SMTP id c15-20020a5d4ccf000000b0015dff622f39so2525836wrt.21 for ; Thu, 16 Sep 2021 07:53:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:subject:from:to:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=5X1WyxGzxFyqToUNiUfnMNvJRCer2A9Q1/BuNT4BZq0=; b=Ixan+zkVyjJ9mRigdSJy/2hqPb+nWxrEW1wtr82lfgHb8KvQUKTAdz8CfCGNuQujzv WZP1j9Ye4pzWrGkyzsg9Ss8hcmXRB0s/g4/eSOeWeC5FW/LOAMAYa1Ny6DDVEsfbNa2m O3+Mq3tC7mQDVnPN2jePn97RB7XQaIQH3ugtavNVWSJKbrHZ3x44BG34cU9fzX1XXNKU z4qIQuEhlM3kvUlcJ1oouevPT4FM74gC624RoPHyHmROPRvHINYQI6bS6LodFyUBxfsd aAoZU2NKGCmXPXIgplph5B3iKaRp/pquPUgDAShox6xVoig/5rhTp6HS3zzMRHUtihid Nebw== X-Gm-Message-State: AOAM532ggdqYCKtN3Ukm5SozRhhZjEdph3Xi3QR9YG890NLHk6Yr3jSA D+ijV4beOYrtBwvvBDWWBBwt5cp4PBSO+EF3byKnsTdTIsS8lRWqHU4NqIu+d6KD5GHkWDue4mL q05wwj6pN+MEEIoYqSzdsyUZF X-Received: by 2002:a5d:4a46:: with SMTP id v6mr6526849wrs.262.1631804003943; Thu, 16 Sep 2021 07:53:23 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxV5xgOkeZB5H90ZCtF/bGfzSRx+hPtuuQ4amdN6EOyU55Iwjfmfiwd7zRDOInLgxpelXGOig== X-Received: by 2002:a5d:4a46:: with SMTP id v6mr6526829wrs.262.1631804003721; Thu, 16 Sep 2021 07:53:23 -0700 (PDT) Received: from gerbillo.redhat.com (146-241-121-250.dyn.eolo.it. [146.241.121.250]) by smtp.gmail.com with ESMTPSA id l13sm3648972wrb.11.2021.09.16.07.53.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Sep 2021 07:53:23 -0700 (PDT) Message-ID: <14ce1879eeeff69a966d2583c45d22e9df0b6f5a.camel@redhat.com> Subject: Re: [syzbot] WARNING in mptcp_sendmsg_frag From: Paolo Abeni To: syzbot , davem@davemloft.net, kuba@kernel.org, linux-kernel@vger.kernel.org, mathew.j.martineau@linux.intel.com, matthieu.baerts@tessares.net, mptcp@lists.linux.dev, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com Date: Thu, 16 Sep 2021 16:53:22 +0200 In-Reply-To: <000000000000bf031105cc00ced8@google.com> References: <000000000000bf031105cc00ced8@google.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2021-09-14 at 21:05 -0700, syzbot wrote: > HEAD commit: f306b90c69ce Merge tag 'smp-urgent-2021-09-12' of git://gi.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=10694371300000 > kernel config: https://syzkaller.appspot.com/x/.config?x=2bfb13fa4527da4e > dashboard link: https://syzkaller.appspot.com/bug?extid=263a248eec3e875baa7b > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+263a248eec3e875baa7b@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 810 at net/mptcp/protocol.c:1366 mptcp_sendmsg_frag+0x1362/0x1bc0 net/mptcp/protocol.c:1366 > Modules linked in: > CPU: 1 PID: 810 Comm: syz-executor.4 Not tainted 5.14.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:mptcp_sendmsg_frag+0x1362/0x1bc0 net/mptcp/protocol.c:1366 > Code: ff 4c 8b 74 24 50 48 8b 5c 24 58 e9 0f fb ff ff e8 13 44 8b f8 4c 89 e7 45 31 ed e8 98 57 2e fe e9 81 f4 ff ff e8 fe 43 8b f8 <0f> 0b 41 bd ea ff ff ff e9 6f f4 ff ff 4c 89 e7 e8 b9 8e d2 f8 e9 > RSP: 0018:ffffc9000531f6a0 EFLAGS: 00010216 > RAX: 000000000000697f RBX: 0000000000000000 RCX: ffffc90012107000 > RDX: 0000000000040000 RSI: ffffffff88eac9e2 RDI: 0000000000000003 > RBP: ffff888078b15780 R08: 0000000000000000 R09: 0000000000000000 > R10: ffffffff88eac017 R11: 0000000000000000 R12: ffff88801de0a280 > R13: 0000000000006b58 R14: ffff888066278280 R15: ffff88803c2fe9c0 > FS: 00007fd9f866e700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007faebcb2f718 CR3: 00000000267cb000 CR4: 00000000001506e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > __mptcp_push_pending+0x1fb/0x6b0 net/mptcp/protocol.c:1547 > mptcp_release_cb+0xfe/0x210 net/mptcp/protocol.c:3003 > release_sock+0xb4/0x1b0 net/core/sock.c:3206 > sk_stream_wait_memory+0x604/0xed0 net/core/stream.c:145 > mptcp_sendmsg+0xc39/0x1bc0 net/mptcp/protocol.c:1749 > inet6_sendmsg+0x99/0xe0 net/ipv6/af_inet6.c:643 > sock_sendmsg_nosec net/socket.c:704 [inline] > sock_sendmsg+0xcf/0x120 net/socket.c:724 > sock_write_iter+0x2a0/0x3e0 net/socket.c:1057 > call_write_iter include/linux/fs.h:2163 [inline] > new_sync_write+0x40b/0x640 fs/read_write.c:507 > vfs_write+0x7cf/0xae0 fs/read_write.c:594 > ksys_write+0x1ee/0x250 fs/read_write.c:647 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x4665f9 > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fd9f866e188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665f9 > RDX: 00000000000e7b78 RSI: 0000000020000000 RDI: 0000000000000003 > RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038 > R13: 0000000000a9fb1f R14: 00007fd9f866e300 R15: 0000000000022000 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. I think (mostly wild guess), this is caused by syzbot enabling tcp skb tx recycling, so that in mptcp_sendmsg_frag() we end up with: ssk->sk_tx_skb_cache != NULL but: skb_ext_find(ssk->sk_tx_skb_cache, SKB_EXT_MPTCP) == NULL. Hard to say given the lack of reproducer. For -net we could do something alike the following (some more testing needed), while for net-next we have the sk_tx_skb_cache removal pending which should address the issue. /P --- diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 2602f1386160..f0673541a764 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1325,7 +1325,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, } alloc_skb: - if (!must_collapse && !ssk->sk_tx_skb_cache && + if (!must_collapse && !mptcp_alloc_tx_skb(sk, ssk, info->data_lock_held)) return 0; From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 960122FAE for ; Thu, 16 Sep 2021 14:53:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631804008; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5X1WyxGzxFyqToUNiUfnMNvJRCer2A9Q1/BuNT4BZq0=; b=Xx0kuKUHa81Awny/mR18T+28VmotR1qCwHPe+yQ5vEJjFV6m9zcIgSsB0TLCRuVrpZVpKK 6bZsNNBVkr42CkmIYqaiUO399eHn22Mjo5lBVXqp78hjsFj0s7MDoahes5tMBZkzZ9m45F 5I9biVaNuHX/0itWQ8qe/7joFQ+pWB4= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-423-uOImO1ZuN7aiMKh62d_CYA-1; Thu, 16 Sep 2021 10:53:25 -0400 X-MC-Unique: uOImO1ZuN7aiMKh62d_CYA-1 Received: by mail-wm1-f70.google.com with SMTP id c2-20020a7bc8420000b0290238db573ab7so2671790wml.5 for ; Thu, 16 Sep 2021 07:53:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:subject:from:to:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=5X1WyxGzxFyqToUNiUfnMNvJRCer2A9Q1/BuNT4BZq0=; b=UlOyn0JIOC3amw2CM/I/LBDinPhXkj2g9WjZyqzhUnfoaweEN9Y+A6E5T7ytG4Su+n mmvBgZtE33Pu6Jgiu6jeQGo6y99Dz1UmeKSMCxbaF9+5rs1l/c0wwBTZ+fDVblZAs9+8 vdgSX82hznoF97dys4lEXbfxuKaZ2Smlhw0Gu07wNqJt4yQd0kyFaX3lTDaDR+3OZlTE SqU0/j5kCZTRcDwl2L/Q/wmqcbUIpmaiQyNCl3MGFUjINzYWREIAl/LKk1Qwrar0xbuk TxP1P/kuZYebDTE3Hw9ms9Wh57WNGSYn2yUvy1pIjX/tJA/cuXilCoekPWadamR6s/Zb dsNw== X-Gm-Message-State: AOAM531T1JGLb0x7Gmy0R9IllCOh1G7EQ+ccnzGl3qKQ5PIK8wPdmVvZ lR5tMqMj0gQYZ9Ll6J/LUrd4nxdYlagAtRAJI4FYnP4O1iBFvCLll6dFdr1Z+gvVsm8Ognj7Z4v 3BOyvQ0z2LqVCvoo= X-Received: by 2002:a5d:4a46:: with SMTP id v6mr6526847wrs.262.1631804003943; Thu, 16 Sep 2021 07:53:23 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxV5xgOkeZB5H90ZCtF/bGfzSRx+hPtuuQ4amdN6EOyU55Iwjfmfiwd7zRDOInLgxpelXGOig== X-Received: by 2002:a5d:4a46:: with SMTP id v6mr6526829wrs.262.1631804003721; Thu, 16 Sep 2021 07:53:23 -0700 (PDT) Received: from gerbillo.redhat.com (146-241-121-250.dyn.eolo.it. [146.241.121.250]) by smtp.gmail.com with ESMTPSA id l13sm3648972wrb.11.2021.09.16.07.53.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Sep 2021 07:53:23 -0700 (PDT) Message-ID: <14ce1879eeeff69a966d2583c45d22e9df0b6f5a.camel@redhat.com> Subject: Re: [syzbot] WARNING in mptcp_sendmsg_frag From: Paolo Abeni To: syzbot , davem@davemloft.net, kuba@kernel.org, linux-kernel@vger.kernel.org, mathew.j.martineau@linux.intel.com, matthieu.baerts@tessares.net, mptcp@lists.linux.dev, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com Date: Thu, 16 Sep 2021 16:53:22 +0200 In-Reply-To: <000000000000bf031105cc00ced8@google.com> References: <000000000000bf031105cc00ced8@google.com> User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pabeni@redhat.com X-Mimecast-Spam-Score: 1 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit On Tue, 2021-09-14 at 21:05 -0700, syzbot wrote: > HEAD commit: f306b90c69ce Merge tag 'smp-urgent-2021-09-12' of git://gi.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=10694371300000 > kernel config: https://syzkaller.appspot.com/x/.config?x=2bfb13fa4527da4e > dashboard link: https://syzkaller.appspot.com/bug?extid=263a248eec3e875baa7b > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+263a248eec3e875baa7b@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 810 at net/mptcp/protocol.c:1366 mptcp_sendmsg_frag+0x1362/0x1bc0 net/mptcp/protocol.c:1366 > Modules linked in: > CPU: 1 PID: 810 Comm: syz-executor.4 Not tainted 5.14.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:mptcp_sendmsg_frag+0x1362/0x1bc0 net/mptcp/protocol.c:1366 > Code: ff 4c 8b 74 24 50 48 8b 5c 24 58 e9 0f fb ff ff e8 13 44 8b f8 4c 89 e7 45 31 ed e8 98 57 2e fe e9 81 f4 ff ff e8 fe 43 8b f8 <0f> 0b 41 bd ea ff ff ff e9 6f f4 ff ff 4c 89 e7 e8 b9 8e d2 f8 e9 > RSP: 0018:ffffc9000531f6a0 EFLAGS: 00010216 > RAX: 000000000000697f RBX: 0000000000000000 RCX: ffffc90012107000 > RDX: 0000000000040000 RSI: ffffffff88eac9e2 RDI: 0000000000000003 > RBP: ffff888078b15780 R08: 0000000000000000 R09: 0000000000000000 > R10: ffffffff88eac017 R11: 0000000000000000 R12: ffff88801de0a280 > R13: 0000000000006b58 R14: ffff888066278280 R15: ffff88803c2fe9c0 > FS: 00007fd9f866e700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007faebcb2f718 CR3: 00000000267cb000 CR4: 00000000001506e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > __mptcp_push_pending+0x1fb/0x6b0 net/mptcp/protocol.c:1547 > mptcp_release_cb+0xfe/0x210 net/mptcp/protocol.c:3003 > release_sock+0xb4/0x1b0 net/core/sock.c:3206 > sk_stream_wait_memory+0x604/0xed0 net/core/stream.c:145 > mptcp_sendmsg+0xc39/0x1bc0 net/mptcp/protocol.c:1749 > inet6_sendmsg+0x99/0xe0 net/ipv6/af_inet6.c:643 > sock_sendmsg_nosec net/socket.c:704 [inline] > sock_sendmsg+0xcf/0x120 net/socket.c:724 > sock_write_iter+0x2a0/0x3e0 net/socket.c:1057 > call_write_iter include/linux/fs.h:2163 [inline] > new_sync_write+0x40b/0x640 fs/read_write.c:507 > vfs_write+0x7cf/0xae0 fs/read_write.c:594 > ksys_write+0x1ee/0x250 fs/read_write.c:647 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x4665f9 > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fd9f866e188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665f9 > RDX: 00000000000e7b78 RSI: 0000000020000000 RDI: 0000000000000003 > RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038 > R13: 0000000000a9fb1f R14: 00007fd9f866e300 R15: 0000000000022000 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. I think (mostly wild guess), this is caused by syzbot enabling tcp skb tx recycling, so that in mptcp_sendmsg_frag() we end up with: ssk->sk_tx_skb_cache != NULL but: skb_ext_find(ssk->sk_tx_skb_cache, SKB_EXT_MPTCP) == NULL. Hard to say given the lack of reproducer. For -net we could do something alike the following (some more testing needed), while for net-next we have the sk_tx_skb_cache removal pending which should address the issue. /P --- diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 2602f1386160..f0673541a764 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1325,7 +1325,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, } alloc_skb: - if (!must_collapse && !ssk->sk_tx_skb_cache && + if (!must_collapse && !mptcp_alloc_tx_skb(sk, ssk, info->data_lock_held)) return 0;