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Message-ID: <CAP=VYLqHW+NOS-gPgUkUpZh-Vim2jkmMT7NK+7uRbg730d=xHw@mail.gmail.com>
Date: Thu, 16 Aug 2012 21:34:25 -0400
From: Paul Gortmaker <paul.gortmaker@...driver.com>
To: Fan Du <fan.du@...driver.com>
Cc: David Miller <davem@...emloft.net>,
Fengguang Wu <fengguang.wu@...el.com>,
Priyanka Jain <Priyanka.Jain@...escale.com>,
netdev@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: suspicious RCU usage in xfrm_net_init()
On Thu, Aug 16, 2012 at 9:07 PM, Fan Du <fan.du@...driver.com> wrote:
>
>
> On 2012年08月16日 23:19, Fengguang Wu wrote:
>>
>> Hi Fan,
>>
>> On Thu, Aug 16, 2012 at 05:36:35PM +0800, Fan Du wrote:
>>>
>>>
>>> Hi, Fengguang
>>>
>>> Could you please try the below patch, see if spewing still there?
>>> thanks
>>
>>
>> Yes, it worked, thank you very much!
>>
>
> Hi, Dave
>
> Could you please pick up this patch?
Please do not make extra work for maintainers by sending attachments,
or requests for status/merge etc. Your 1st patch had to be manually
set to an RFC, and now you add another patch less than 24h later.
Please see:
http://patchwork.ozlabs.org/patch/177934/
http://patchwork.ozlabs.org/patch/178132/
Also, a patch should describe the problem it solves (i.e. the symptom
the end user sees), and how the problem originated, and why the fix
in the patch is the _right_ fix. The worst description a commit log
can have is one that just describes the C change in words, since
most people can read C on their own.
Here you add "_bh" in the code and then repeat exactly that in
the commit log. Your commit log does not tell me when it broke,
or why it broke, or who had their use case broken. Can you see
why this is not acceptable?
Please take the time to look at the traffic in netdev, and read
the feedback given by maintainers on other patches, so that the
common errors are understood by you, and not repeated. It
will be time well spent!
Thanks,
Paul.
---
> thanks
>
>
>
>
>> btw, your email client wraps long lines..
>>
> Oh, I will definitely fix this.
> thanks feng guang for the testing :)
>
>
>
>> Thanks,
>> Fengguang
>>
>>> From a3f86ecc3ee16ff81d49416bbf791780422988b3 Mon Sep 17 00:00:00 2001
>>> From: Fan Du<fan.du@...driver.com>
>>> Date: Thu, 16 Aug 2012 17:31:25 +0800
>>> Subject: [PATCH] Use rcu_dereference_bh to deference pointer
>>> protected by rcu_read_lock_bh
>>>
>>> Signed-off-by: Fan Du<fan.du@...driver.com>
>>> ---
>>> net/xfrm/xfrm_policy.c | 2 +-
>>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
>>> index 5ad4d2c..75a9d6a 100644
>>> --- a/net/xfrm/xfrm_policy.c
>>> +++ b/net/xfrm/xfrm_policy.c
>>> @@ -2501,7 +2501,7 @@ static void __net_init
>>> xfrm_dst_ops_init(struct net *net)
>>> struct xfrm_policy_afinfo *afinfo;
>>>
>>> rcu_read_lock_bh();
>>> - afinfo = rcu_dereference(xfrm_policy_afinfo[AF_INET]);
>>> + afinfo = rcu_dereference_bh(xfrm_policy_afinfo[AF_INET]);
>>> if (afinfo)
>>> net->xfrm.xfrm4_dst_ops = *afinfo->dst_ops;
>>> #if IS_ENABLED(CONFIG_IPV6)
>>> --
>>> 1.7.1
>>>
>>>
>>>
>>>
>>> On 2012年08月16日 15:37, Fengguang Wu wrote:
>>>>
>>>> Hi Priyanka,
>>>>
>>>> The below warning shows up, probably related to this commit:
>>>>
>>>> 418a99ac6ad487dc9c42e6b0e85f941af56330f2 Replace rwlock on
>>>> xfrm_policy_afinfo with rcu
>>>>
>>>> [ 0.921216]
>>>> [ 0.921645] ===============================
>>>> [ 0.922766] [ INFO: suspicious RCU usage. ]
>>>> [ 0.923887] 3.5.0-01540-g1669891 #64 Not tainted
>>>> [ 0.925123] -------------------------------
>>>> [ 0.932860] /c/kernel-tests/src/tip/net/xfrm/xfrm_policy.c:2504
>>>> suspicious rcu_dereference_check() usage!
>>>> [ 0.935361]
>>>> [ 0.935361] other info that might help us debug this:
>>>> [ 0.935361]
>>>> [ 0.937472]
>>>> [ 0.937472] rcu_scheduler_active = 1, debug_locks = 0
>>>> [ 0.939182] 2 locks held by swapper/1:
>>>> [ 0.940171] #0: (net_mutex){+.+.+.}, at: [<ffffffff814e1ad0>]
>>>> register_pernet_subsys+0x21/0x57
>>>> [ 0.942705] #1: (rcu_read_lock_bh){......}, at:
>>>> [<ffffffff822c7329>] xfrm_net_init+0x1e4/0x437
>>>> [ 0.951507]
>>>> [ 0.951507] stack backtrace:
>>>> [ 0.952660] Pid: 1, comm: swapper Not tainted 3.5.0-01540-g1669891
>>>> #64
>>>> [ 0.954364] Call Trace:
>>>> [ 0.955074] [<ffffffff8108b375>] lockdep_rcu_suspicious+0x174/0x187
>>>> [ 0.956736] [<ffffffff822c7453>] xfrm_net_init+0x30e/0x437
>>>> [ 0.958205] [<ffffffff822c7329>] ? xfrm_net_init+0x1e4/0x437
>>>> [ 0.959712] [<ffffffff814e134a>] ops_init+0x1bb/0x1ff
>>>> [ 0.961067] [<ffffffff810861f9>] ? trace_hardirqs_on+0x1b/0x24
>>>> [ 0.962644] [<ffffffff814e17cd>]
>>>> register_pernet_operations.isra.5+0x9d/0xfe
>>>> [ 0.971376] [<ffffffff814e1adf>] register_pernet_subsys+0x30/0x57
>>>> [ 0.972992] [<ffffffff822c7130>] xfrm_init+0x17/0x2c
>>>> [ 0.974316] [<ffffffff822c2f8c>] ip_rt_init+0x82/0xe7
>>>> [ 0.975668] [<ffffffff822c31dc>] ip_init+0x10/0x25
>>>> [ 0.976952] [<ffffffff822c3f77>] inet_init+0x235/0x360
>>>> [ 0.978352] [<ffffffff822c3d42>] ? devinet_init+0xf2/0xf2
>>>> [ 0.979808] [<ffffffff82283252>] do_one_initcall+0xb4/0x203
>>>> [ 0.981313] [<ffffffff8228354a>] kernel_init+0x1a9/0x29a
>>>> [ 0.982732] [<ffffffff822826d9>] ? loglevel+0x46/0x46
>>>> [ 0.990889] [<ffffffff816d3d84>] kernel_thread_helper+0x4/0x10
>>>> [ 0.992472] [<ffffffff816d262c>] ? retint_restore_args+0x13/0x13
>>>> [ 0.994076] [<ffffffff822833a1>] ? do_one_initcall+0x203/0x203
>>>> [ 0.995636] [<ffffffff816d3d80>] ? gs_change+0x13/0x13
>>>> [ 0.997197] TCP established hash table entries: 8192 (order: 5,
>>>> 131072 bytes)
>>>> [ 1.000074] TCP bind hash table entries: 8192 (order: 7, 655360
>>>> bytes)
>>>>
>>>> Thanks,
>>>> Fengguang
>>>
>>>
>>> --
>>>
>>> Love each day!
>>> --fan
>>
>>
>
> --
>
> Love each day!
> --fan
--
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