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From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Fri, 27 Jan 2017 15:22:43 -0800
Message-ID: <CAM_iQpXNwZbkF+zoR5qdREcK6ZFt3ODbrpRB38WidLkcUWt5dw@mail.gmail.com>
Subject: Re: net: suspicious RCU usage in nf_hook
To: Dmitry Vyukov <dvyukov@google.com>
Cc: David Miller <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Eric Dumazet <edumazet@google.com>, James Morris <jmorris@namei.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Patrick McHardy <kaber@trash.net>, netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        netfilter-devel@vger.kernel.org,
        syzkaller <syzkaller@googlegroups.com>
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On Fri, Jan 27, 2017 at 1:15 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> stack backtrace:
> CPU: 2 PID: 23111 Comm: syz-executor14 Not tainted 4.10.0-rc5+ #192
> 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
>  lockdep_rcu_suspicious+0x139/0x180 kernel/locking/lockdep.c:4452
>  rcu_preempt_sleep_check include/linux/rcupdate.h:560 [inline]
>  ___might_sleep+0x560/0x650 kernel/sched/core.c:7748
>  __might_sleep+0x95/0x1a0 kernel/sched/core.c:7739
>  mutex_lock_nested+0x24f/0x1730 kernel/locking/mutex.c:752
>  atomic_dec_and_mutex_lock+0x119/0x160 kernel/locking/mutex.c:1060
>  __static_key_slow_dec+0x7a/0x1e0 kernel/jump_label.c:149
>  static_key_slow_dec+0x51/0x90 kernel/jump_label.c:174
>  net_disable_timestamp+0x3b/0x50 net/core/dev.c:1728
>  sock_disable_timestamp+0x98/0xc0 net/core/sock.c:403
>  __sk_destruct+0x27d/0x6b0 net/core/sock.c:1441
>  sk_destruct+0x47/0x80 net/core/sock.c:1460

jump label uses a mutex and we call jump label API in softIRQ context...
Maybe we have to move it to a work struct as what we did for netlink.