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Date: Wed, 19 Dec 2012 16:44:08 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Xiaotian Feng <xtfeng@gmail.com>, akpm@linux-foundation.org,
        Xiaotian Feng <dannyfeng@tencent.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] proc: fix inconsistent lock state
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On Wed, Dec 19, 2012 at 04:13:30AM -0800, Eric W. Biederman wrote:

> Something doesn't feel right.   I don't think there should be a path where we get to proc_free_inum from bh context.
> 
> Rcu callbacks should be running in process context (if a special one).

No, they are not.  They run from softirq context, which makes for all kinds
of interesting kludges being required in various places.