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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Sun, 1 Mar 2020 22:23:07 +0100
Message-ID: <CAJZ5v0jTSKd_23fJhM+XUmFX_yTjcD+c_s1Jvi3HA1EmXPkzZw@mail.gmail.com>
Subject: Re: [PATCH 1/2] drivers: base: power: main: Use built-in RCU list checking
To:     Joel Fernandes <joel@joelfernandes.org>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        madhuparnabhowmik10@gmail.com,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Pavel Machek <pavel@ucw.cz>, Len Brown <len.brown@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        frextrite@gmail.com,
        linux-kernel-mentees@lists.linuxfoundation.org, paulmck@kernel.org
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On Sun, Mar 1, 2020 at 9:53 PM <joel@joelfernandes.org> wrote:
>
>
>
> On March 1, 2020 3:12:53 PM EST, "Rafael J. Wysocki" <rafael@kernel.org> wrote:
> >On Fri, Feb 28, 2020 at 6:47 PM <madhuparnabhowmik10@gmail.com> wrote:
> >>
> >> From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> >>
> >> This patch passes the cond argument to list_for_each_entry_rcu()
> >> to fix the following false-positive lockdep warnings:
> >>
> >> [  330.302784] =============================
> >> [  330.302789] WARNING: suspicious RCU usage
> >> [  330.302796] 5.6.0-rc1+ #5 Not tainted
> >> [  330.302801] -----------------------------
> >> [  330.302808] drivers/base/power/main.c:326 RCU-list traversed in
> >non-reader section!!
> >>
> >> [  330.303303] =============================
> >> [  330.303307] WARNING: suspicious RCU usage
> >> [  330.303311] 5.6.0-rc1+ #5 Not tainted
> >> [  330.303315] -----------------------------
> >> [  330.303319] drivers/base/power/main.c:1698 RCU-list traversed in
> >non-reader section!!
> >>
> >> [  331.934969] =============================
> >> [  331.934971] WARNING: suspicious RCU usage
> >> [  331.934973] 5.6.0-rc1+ #5 Not tainted
> >> [  331.934975] -----------------------------
> >> [  331.934977] drivers/base/power/main.c:1238 RCU-list traversed in
> >non-reader section!!
> >>
> >> [  332.467772] WARNING: suspicious RCU usage
> >> [  332.467775] 5.6.0-rc1+ #5 Not tainted
> >> [  332.467775] -----------------------------
> >> [  332.467778] drivers/base/power/main.c:269 RCU-list traversed in
> >non-reader section!!
> >
> >I don't see these warnings in the kernels run locally here.
> >
> >What do you do to get them?
> >
> >Joel, any comments here?
>
> You have to enable lockdep in your config. Does your setup have that?

CONFIG_LOCK_DEBUGGING_SUPPORT=y
CONFIG_PROVE_LOCKING=y
CONFIG_DEBUG_SPINLOCK=y
CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_LOCKDEP=y

Anything else?