From: Guenter Roeck <linux@roeck-us.net>
To: madhuparnabhowmik10@gmail.com
Cc: paulmck@kernel.org, josh@joshtriplett.org, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
joel@joelfernandes.org, linux-kernel@vger.kernel.org,
Amol Grover <frextrite@gmail.com>
Subject: Re: [PATCH] Default enable RCU list lockdep debugging with PROVE_RCU
Date: Thu, 5 Mar 2020 07:52:38 -0800 [thread overview]
Message-ID: <20200305155238.GA8669@roeck-us.net> (raw)
In-Reply-To: <20200228092451.10455-1-madhuparnabhowmik10@gmail.com>
On Fri, Feb 28, 2020 at 02:54:51PM +0530, madhuparnabhowmik10@gmail.com wrote:
> From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
>
> This patch default enables CONFIG_PROVE_RCU_LIST option with
> CONFIG_PROVE_RCU for RCU list lockdep debugging.
>
> With this change, RCU list lockdep debugging will be default
> enabled in CONFIG_PROVE_RCU=y kernels.
>
> Most of the RCU users (in core kernel/, drivers/, and net/
> subsystem) have already been modified to include lockdep
> expressions hence RCU list debugging can be enabled by
> default.
>
> However, there are still chances of enountering
> false-positive lockdep splats because not everything is converted,
> in case RCU list primitives are used in non-RCU read-side critical
> section but under the protection of a lock. It would be okay to
> have a few false-positives, as long as bugs are identified, since this
> patch only affects debugging kernels.
>
> Co-developed-by: Amol Grover <frextrite@gmail.com>
> Signed-off-by: Amol Grover <frextrite@gmail.com>
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Who is going to fix the fallout ?
fs/btrfs/block-group.c:2011 RCU-list traversed in non-reader section!!
kernel/kprobes.c:329 RCU-list traversed in non-reader section!!
net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!!
This is just from my boot tests. I'll keep PROVE_RCU enabled for the
time being, but unless the noise is addressed I'll have to disable it
because otherwise the real problems disappear in the noise.
Guenter
next prev parent reply other threads:[~2020-03-05 15:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200305105038eucas1p1bad0e1bd4b12a28e05ecd14615b31af2@eucas1p1.samsung.com>
2020-02-28 9:24 ` [PATCH] Default enable RCU list lockdep debugging with PROVE_RCU madhuparnabhowmik10
2020-02-28 14:21 ` Joel Fernandes
2020-02-28 14:37 ` Paul E. McKenney
2020-03-05 10:50 ` Marek Szyprowski
2020-03-05 17:23 ` Madhuparna Bhowmik
2020-03-05 15:52 ` Guenter Roeck [this message]
2020-03-05 17:39 ` Madhuparna Bhowmik
2020-03-05 18:58 ` Guenter Roeck
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