linux-kernel - Re: [RFC PATCH 9/9] debugfs: free debugfs

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Message-ID: <1492508367.2472.9.camel@sipsolutions.net>
Date:   Tue, 18 Apr 2017 11:39:27 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     paulmck@...ux.vnet.ibm.com, Nicolai Stange <nicstange@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 9/9] debugfs: free debugfs_fsdata instances

On Mon, 2017-04-17 at 09:01 -0700, Paul E. McKenney wrote:

> If you have not already done so, please run this with debug enabled,
> especially CONFIG_PROVE_LOCKING=y (which implies CONFIG_PROVE_RCU=y).
> This is important because there are configurations for which the
> deadlocks you saw with SRCU turn into silent failure, including
> memory corruption.
> CONFIG_PROVE_RCU=y will catch many of those situations.

Can you elaborate on that? I think we may have had CONFIG_PROVE_RCU
enabled in the builds where we saw the problem, but I'm not sure.

Can you say which configurations you're thinking of? And perhaps what
kind of corruption you're thinking of also? I'm having a hard time
imagining any corruption that should happen?

Nicolai probably never even ran into this problem, though it should be
easy to reproduce.

johannes