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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Thu, 11 Oct 2018 09:59:46 +0200
Message-ID: <CACT4Y+Ym3_NuqWrgHXWfTahWTm17xi_2gjy8hvuDeyUCPuYXUQ@mail.gmail.com>
Subject: Re: net/tipc: recursive locking in tipc_link_reset
To:     Jon Maloy <jon.maloy@ericsson.com>,
        David Miller <davem@davemloft.net>,
        Ying Xue <ying.xue@windriver.com>,
        netdev <netdev@vger.kernel.org>,
        tipc-discussion@lists.sourceforge.net,
        LKML <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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On Thu, Oct 11, 2018 at 9:55 AM, Dmitry Vyukov <dvyukov@google.com> wrote:
> Hi,
>
> I am getting the following error while booting the latest kernel on
> bb2d8f2f61047cbde08b78ec03e4ebdb01ee5434 (Oct 10). Config is attached.
>
> Since this happens during boot, this makes LOCKDEP completely
> unusable, does not allow to discover any other locking issues and
> masks all new bugs being introduced into kernel.
> Please fix asap.
> Thanks

-parthasarathy.bhuvaragan address as it gives me bounces
but this is highly likely due to:

commit 3f32d0be6c16b902b687453c962d17eea5b8ea19
Author: Parthasarathy Bhuvaragan
Date:   Tue Sep 25 22:09:10 2018 +0200

    tipc: lock wakeup & inputq at tipc_link_reset()


> WARNING: possible recursive locking detected
> 4.19.0-rc7+ #14 Not tainted
> --------------------------------------------
> swapper/0/1 is trying to acquire lock:
> 00000000dcfc0fc8 (&(&list->lock)->rlock#4){+...}, at: spin_lock_bh
> include/linux/spinlock.h:334 [inline]
> 00000000dcfc0fc8 (&(&list->lock)->rlock#4){+...}, at:
> tipc_link_reset+0x125/0xdf0 net/tipc/link.c:850
>
> but task is already holding lock:
> 00000000cbb9b036 (&(&list->lock)->rlock#4){+...}, at: spin_lock_bh
> include/linux/spinlock.h:334 [inline]
> 00000000cbb9b036 (&(&list->lock)->rlock#4){+...}, at:
> tipc_link_reset+0xfa/0xdf0 net/tipc/link.c:849
>
> other info that might help us debug this:
>  Possible unsafe locking scenario:
>
>        CPU0
>        ----
>   lock(&(&list->lock)->rlock#4);
>   lock(&(&list->lock)->rlock#4);
>
>  *** DEADLOCK ***
>
>  May be due to missing lock nesting notation
>
> 2 locks held by swapper/0/1:
>  #0: 00000000f7539d34 (pernet_ops_rwsem){+.+.}, at:
> register_pernet_subsys+0x19/0x40 net/core/net_namespace.c:1051
>  #1: 00000000cbb9b036 (&(&list->lock)->rlock#4){+...}, at:
> spin_lock_bh include/linux/spinlock.h:334 [inline]
>  #1: 00000000cbb9b036 (&(&list->lock)->rlock#4){+...}, at:
> tipc_link_reset+0xfa/0xdf0 net/tipc/link.c:849
>
> stack backtrace:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc7+ #14
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x1af/0x295 lib/dump_stack.c:113
>  print_deadlock_bug kernel/locking/lockdep.c:1759 [inline]
>  check_deadlock kernel/locking/lockdep.c:1803 [inline]
>  validate_chain kernel/locking/lockdep.c:2399 [inline]
>  __lock_acquire+0xf1e/0x3c60 kernel/locking/lockdep.c:3411
>  lock_acquire+0x1db/0x520 kernel/locking/lockdep.c:3900
>  __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
>  _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168
>  spin_lock_bh include/linux/spinlock.h:334 [inline]
>  tipc_link_reset+0x125/0xdf0 net/tipc/link.c:850
>  tipc_link_bc_create+0xb5/0x1f0 net/tipc/link.c:526
>  tipc_bcast_init+0x59b/0xab0 net/tipc/bcast.c:521
>  tipc_init_net+0x472/0x610 net/tipc/core.c:82
>  ops_init+0xf7/0x520 net/core/net_namespace.c:129
>  __register_pernet_operations net/core/net_namespace.c:940 [inline]
>  register_pernet_operations+0x453/0xac0 net/core/net_namespace.c:1011
>  register_pernet_subsys+0x28/0x40 net/core/net_namespace.c:1052
>  tipc_init+0x83/0x104 net/tipc/core.c:140
>  do_one_initcall+0x109/0x70a init/main.c:885
>  do_initcall_level init/main.c:953 [inline]
>  do_initcalls init/main.c:961 [inline]
>  do_basic_setup init/main.c:979 [inline]
>  kernel_init_freeable+0x4bd/0x57f init/main.c:1144
>  kernel_init+0x13/0x180 init/main.c:1063
>  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413