From: James Chapman <jchapman@katalix•com>
To: Jarek Poplawski <jarkao2@gmail•com>
Cc: netdev@vger•kernel.org
Subject: Re: [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver
Date: Mon, 11 Feb 2008 22:19:35 +0000 [thread overview]
Message-ID: <47B0C9F7.5040200@katalix.com> (raw)
In-Reply-To: <47B09A90.7040508@gmail.com>
Jarek Poplawski wrote:
> James Chapman wrote, On 02/11/2008 10:22 AM:
>
>> Fix locking issues in the pppol2tp driver which can cause a kernel
>> crash on SMP boxes when hundreds of L2TP sessions are created/deleted
>> simultaneously (ISP environment). The driver was violating read_lock()
>> and write_lock() scheduling rules so we now consistently use the _irq
>> variants of the lock functions.
> ...
>
> Hi,
>
> Could you explain what exactly scheduling rules do you mean here,
> and why disabling interrupts is the best solution for this?
Below is example output from lockdep. The oops is reproducible when
creating/deleting lots of sessions while passing data. The lock is being
acquired for read and write in softirq contexts.
Is there a better way to fix this?
=================================
[ INFO: inconsistent lock state ]
2.6.24-core2 #1
---------------------------------
inconsistent {in-softirq-R} -> {softirq-on-W} usage.
openl2tpd/3215 [HC0[0]:SC0[0]:HE1:SE1] takes:
(&tunnel->hlist_lock){---?}, at: [<f8eea157>]
pppol2tp_connect+0x517/0x6d0 [pppol2tp]
{in-softirq-R} state was registered at:
[<c014edaf>] __lock_acquire+0x6bf/0x10a0
[<c03ee75b>] fn_hash_lookup+0x1b/0xe0
[<c014f804>] lock_acquire+0x74/0xa0
[<f8ee859f>] pppol2tp_session_find+0x1f/0x80 [pppol2tp]
[<c040427a>] _read_lock+0x2a/0x40
[<f8ee859f>] pppol2tp_session_find+0x1f/0x80 [pppol2tp]
[<f8ee859f>] pppol2tp_session_find+0x1f/0x80 [pppol2tp]
[<f8ee8dc8>] pppol2tp_recv_core+0xd8/0x960 [pppol2tp]
[<f8d3f72a>] ipt_do_table+0x23a/0x500 [ip_tables]
[<f8ee967e>] pppol2tp_udp_encap_recv+0x2e/0x70 [pppol2tp]
[<c0403fb4>] _read_unlock+0x14/0x20
[<c03dd696>] udp_queue_rcv_skb+0x106/0x2a0
[<c03ddc5a>] __udp4_lib_rcv+0x42a/0x7e0
[<f8d57090>] ipt_hook+0x0/0x20 [iptable_filter]
[<c03bc2da>] ip_local_deliver_finish+0xca/0x1c0
[<c03bc23e>] ip_local_deliver_finish+0x2e/0x1c0
[<c03bbfaf>] ip_rcv_finish+0xff/0x360
[<c03bc6dc>] ip_rcv+0x20c/0x2a0
[<c03bbeb0>] ip_rcv_finish+0x0/0x360
[<c039ad87>] netif_receive_skb+0x317/0x4b0
[<c039ab70>] netif_receive_skb+0x100/0x4b0
[<f8d9627a>] e1000_clean_rx_irq_ps+0x28a/0x560 [e1000]
[<f8d95ff0>] e1000_clean_rx_irq_ps+0x0/0x560 [e1000]
[<f8d9384d>] e1000_clean+0x5d/0x290 [e1000]
[<c039d580>] net_rx_action+0x1a0/0x2a0
[<c039d43f>] net_rx_action+0x5f/0x2a0
[<c0131e72>] __do_softirq+0x92/0x120
[<c0131f78>] do_softirq+0x78/0x80
[<c010b15a>] do_IRQ+0x4a/0xa0
[<c0108dcc>] common_interrupt+0x24/0x34
[<c0108dd6>] common_interrupt+0x2e/0x34
[<c01062d6>] mwait_idle_with_hints+0x46/0x60
[<c0106550>] mwait_idle+0x0/0x20
[<c0106694>] cpu_idle+0x74/0xe0
[<c0536a9a>] start_kernel+0x30a/0x3a0
[<c0536150>] unknown_bootoption+0x0/0x1f0
[<ffffffff>] 0xffffffff
irq event stamp: 275
hardirqs last enabled at (275): [<c0132317>] local_bh_enable_ip+0xa7/0x120
hardirqs last disabled at (273): [<c01322a6>] local_bh_enable_ip+0x36/0x120
softirqs last enabled at (274): [<f8eab8bc>]
ppp_register_channel+0xdc/0xf0 [ppp_generic]
softirqs last disabled at (272): [<c040410b>] _spin_lock_bh+0xb/0x40
--
James Chapman
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development
next prev parent reply other threads:[~2008-02-11 22:19 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-11 9:22 [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver James Chapman
2008-02-11 18:57 ` Jarek Poplawski
2008-02-11 22:19 ` James Chapman [this message]
2008-02-11 22:49 ` Jarek Poplawski
2008-02-11 22:55 ` Jarek Poplawski
2008-02-11 23:42 ` James Chapman
2008-02-12 10:42 ` Jarek Poplawski
2008-02-11 23:41 ` James Chapman
2008-02-12 5:30 ` David Miller
2008-02-12 10:58 ` James Chapman
2008-02-12 13:24 ` Jarek Poplawski
2008-02-13 6:00 ` David Miller
2008-02-13 7:29 ` Jarek Poplawski
2008-02-14 13:00 ` Jarek Poplawski
2008-02-18 22:09 ` James Chapman
2008-02-18 23:01 ` Jarek Poplawski
2008-02-19 9:09 ` James Chapman
2008-02-19 4:29 ` David Miller
2008-02-19 9:03 ` James Chapman
2008-02-19 10:30 ` Jarek Poplawski
2008-02-19 10:36 ` Jarek Poplawski
2008-02-19 14:37 ` James Chapman
2008-02-19 23:06 ` Jarek Poplawski
2008-02-19 23:28 ` Jarek Poplawski
2008-02-20 16:02 ` James Chapman
2008-02-20 18:38 ` Jarek Poplawski
2008-02-20 22:37 ` James Chapman
2008-02-21 8:59 ` Jarek Poplawski
2008-02-21 9:53 ` James Chapman
2008-02-21 12:08 ` Jarek Poplawski
2008-02-21 17:09 ` Jarek Poplawski
2008-02-25 12:19 ` James Chapman
2008-02-25 13:05 ` Jarek Poplawski
2008-02-25 13:39 ` Jarek Poplawski
2008-02-25 14:02 ` Jarek Poplawski
2008-02-25 21:58 ` Jarek Poplawski
2008-02-26 12:14 ` James Chapman
2008-02-26 13:03 ` Jarek Poplawski
2008-02-26 13:18 ` Jarek Poplawski
2008-02-26 20:00 ` Jarek Poplawski
2008-03-02 20:29 ` James Chapman
2008-03-03 8:22 ` Jarek Poplawski
2008-03-03 9:35 ` Jarek Poplawski
2008-02-27 10:54 ` [PATCH][PPPOL2TP] add missing sock_put() in pppol2tp_recv_dequeue() Jarek Poplawski
2008-03-02 20:31 ` James Chapman
2008-03-04 4:49 ` David Miller
2008-02-27 11:48 ` [PATCH][PPPOL2TP] add missing sock_put() in pppol2tp_tunnel_closeall() Jarek Poplawski
2008-03-02 20:32 ` James Chapman
2008-03-04 4:49 ` David Miller
2008-02-22 14:16 ` [PATCH][NET] sock.c: sk_dst_lock lockdep keys and names per af_family Jarek Poplawski
2008-02-12 7:19 ` [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver Jarek Poplawski
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