From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751240AbdBBJGG (ORCPT ); Thu, 2 Feb 2017 04:06:06 -0500 Received: from mail-ua0-f182.google.com ([209.85.217.182]:35117 "EHLO mail-ua0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751206AbdBBJGB (ORCPT ); Thu, 2 Feb 2017 04:06:01 -0500 MIME-Version: 1.0 In-Reply-To: References: From: Dmitry Vyukov Date: Thu, 2 Feb 2017 10:05:39 +0100 Message-ID: Subject: Re: net/tcp: warning in tcp_try_coalesce/skb_try_coalesce To: Eric Dumazet Cc: Andrey Konovalov , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev , LKML , Kostya Serebryany , syzkaller Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 31, 2017 at 3:27 PM, 'Eric Dumazet' via syzkaller wrote: > On Tue, Jan 31, 2017 at 5:17 AM, Andrey Konovalov wrote: >> Hi, >> >> I've got the following error report while running the syzkaller fuzzer. >> >> On commit 566cf877a1fcb6d6dc0126b076aad062054c2637 (4.10-rc6). >> >> The fuzzer hits this issue quite often, but I don't have a working reproducer. >> >> WARNING: CPU: 3 PID: 7091 at net/core/skbuff.c:4331 >> skb_try_coalesce+0x14b1/0x1f80 net/core/skbuff.c:4331 >> Kernel panic - not syncing: panic_on_warn set ... ... > Have you tried the patch we added recently into net-next ? > > https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=158f323b9868b59967ad96957c4ca388161be321 I've tried this patch, and it does _not_ help. I am currently on a2ca3d617944417e9dd5f09fc8a4549cda115f4f, and I applied the patch on top (had to do a little merging in af_netlink.c): https://gist.githubusercontent.com/dvyukov/b4fd206f7dde763b3113a4543c57e7bb/raw/784c5b1bcb06f2a22c55eb4c4f8f83d627cd1ab9/gistfile1.txt Still getting the same warning. But now I have a repro: https://gist.githubusercontent.com/dvyukov/88fdb6d93507b36f81377191b0694f9b/raw/81cc11e8b78b6bbc5cffc79b442ce998c49af226/gistfile1.txt WARNING: CPU: 2 PID: 2958 at net/core/skbuff.c:4339 skb_try_coalesce+0x154c/0x2020 net/core/skbuff.c:4339 Kernel panic - not syncing: panic_on_warn set ... CPU: 2 PID: 2958 Comm: a.out Not tainted 4.10.0-rc6+ #206 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:15 [inline] dump_stack+0x2ee/0x3ef lib/dump_stack.c:51 panic+0x1fb/0x412 kernel/panic.c:179 __warn+0x1c4/0x1e0 kernel/panic.c:539 warn_slowpath_null+0x2c/0x40 kernel/panic.c:582 skb_try_coalesce+0x154c/0x2020 net/core/skbuff.c:4339 tcp_try_coalesce+0x16f/0x560 net/ipv4/tcp_input.c:4337 tcp_queue_rcv+0x12d/0x790 net/ipv4/tcp_input.c:4572 tcp_data_queue+0x96f/0x46b0 net/ipv4/tcp_input.c:4681 tcp_rcv_state_process+0xd92/0x42c0 net/ipv4/tcp_input.c:6130 tcp_v4_do_rcv+0x56b/0x940 net/ipv4/tcp_ipv4.c:1426 sk_backlog_rcv include/net/sock.h:893 [inline] __release_sock+0x126/0x3a0 net/core/sock.c:2053 release_sock+0xa5/0x2b0 net/core/sock.c:2540 inet_shutdown+0x1a8/0x350 net/ipv4/af_inet.c:833 SYSC_shutdown net/socket.c:1840 [inline] SyS_shutdown+0x23d/0x2d0 net/socket.c:1831 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: 0033:0x443b39 RSP: 002b:00007ffcfd0814f8 EFLAGS: 00000206 ORIG_RAX: 0000000000000030 RAX: ffffffffffffffda RBX: 00000000004031d0 RCX: 0000000000443b39 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 00000000004002b0 R13: 00000000004031d0 R14: 0000000000403260 R15: 0000000000000000 Kernel Offset: disabled Rebooting in 86400 seconds..