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Message-ID: <1391016668.28432.57.camel@edumazet-glaptop2.roam.corp.google.com>
Date: Wed, 29 Jan 2014 09:31:08 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: Or Gerlitz <ogerlitz@...lanox.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org,
dan.carpenter@...cle.com, Shlomo Pongratz <shlomop@...lanox.com>
Subject: Re: [PATCH net] net/ipv4: Use non-atomic allocation of udp offloads
structure instance
On Wed, 2014-01-29 at 18:42 +0200, Or Gerlitz wrote:
> On 29/01/2014 18:20, Eric Dumazet wrote:
> > Could you also fix all the rcu_dereference() calls ?
> >
> > Try CONFIG_PROVE_RCU=y
>
> Thanks Eric, I tried this out now and got one alarm on udp_add_offload,
> which I will loop up how to fix,
> do you see anything else?
>
>
You should have same issue in udp_del_offload()
(Lockdep triggers once only)
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.13.0+ #109 Not tainted
> -------------------------------
> net/ipv4/udp_offload.c:112 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 1, debug_locks = 0
> 4 locks held by kworker/2:2/2752:
> #0: (vxlan){.+.+.+}, at: [<ffffffff8108bd5a>]
> process_one_work+0x15a/0x710
> #1: ((&vxlan->sock_work)){+.+.+.}, at: [<ffffffff8108bd5a>]
> process_one_work+0x15a/0x710
> #2: (&(&vn->sock_lock)->rlock){+.+...}, at: [<ffffffffa03caae3>]
> vxlan_sock_add+0x323/0xb70 [vxlan]
> #3: (udp_offload_lock){+.+...}, at: [<ffffffff814d22e1>]
> udp_add_offload+0x41/0xd0
>
> stack backtrace:
> CPU: 2 PID: 2752 Comm: kworker/2:2 Not tainted 3.13.0+ #109
> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2007
> Workqueue: vxlan vxlan_sock_work [vxlan]
> 0000000000000001 ffff8800d1949bf8 ffffffff81528412 0000000000000002
> ffff88021ef2e060 ffff8800d1949c28 ffffffff810b8373 ffff880218f59160
> 0000000000000000 ffffffff81aa3540 ffff88021dcaf000 ffff8800d1949c48
> Call Trace:
> [<ffffffff81528412>] dump_stack+0x51/0x77
> [<ffffffff810b8373>] lockdep_rcu_suspicious+0x103/0x140
> [<ffffffff814d234a>] udp_add_offload+0xaa/0xd0
> [<ffffffffa03cb0ad>] vxlan_sock_add+0x8ed/0xb70 [vxlan]
> [<ffffffffa03caa77>] ? vxlan_sock_add+0x2b7/0xb70 [vxlan]
> [<ffffffffa03ce390>] ? vxlan_xmit+0x650/0x650 [vxlan]
> [<ffffffffa03cb330>] ? vxlan_sock_add+0xb70/0xb70 [vxlan]
> [<ffffffff81291f7c>] ? delay_tsc+0x6c/0xd0
> [<ffffffffa03cb439>] vxlan_sock_work+0x109/0x260 [vxlan]
> [<ffffffffa03cb330>] ? vxlan_sock_add+0xb70/0xb70 [vxlan]
> [<ffffffff8108bdd1>] process_one_work+0x1d1/0x710
> [<ffffffff8108bd5a>] ? process_one_work+0x15a/0x710
> [<ffffffff8108c432>] worker_thread+0x122/0x400
> [<ffffffff8108c310>] ? process_one_work+0x710/0x710
> [<ffffffff810943fe>] kthread+0xde/0x100
> [<ffffffff81094320>] ? __init_kthread_worker+0x70/0x70
> [<ffffffff8152f3bc>] ret_from_fork+0x7c/0xb0
> [<ffffffff81094320>] ? __init_kthread_worker+0x70/0x70
>
> --
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