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From:   Thomas Gleixner <tglx@linutronix.de>
To:     "Li\, Aubrey" <aubrey.li@linux.intel.com>,
        Vineeth Remanan Pillai <vpillai@digitalocean.com>,
        Nishanth Aravamudan <naravamudan@digitalocean.com>,
        Julien Desfossez <jdesfossez@digitalocean.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Tim Chen <tim.c.chen@linux.intel.com>, mingo@kernel.org,
        pjt@google.com, torvalds@linux-foundation.org
Cc:     "Joel Fernandes \(Google\)" <joel@joelfernandes.org>,
        linux-kernel@vger.kernel.org, subhra.mazumdar@oracle.com,
        fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com,
        Phil Auld <pauld@redhat.com>, Aaron Lu <aaron.lwe@gmail.com>,
        Aubrey Li <aubrey.intel@gmail.com>,
        Valentin Schneider <valentin.schneider@arm.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Joel Fernandes <joelaf@google.com>, vineethrp@gmail.com,
        Chen Yu <yu.c.chen@intel.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Tim Chen <tim.c.chen@intel.com>,
        "Paul E . McKenney" <paulmck@kernel.org>
Subject: Re: [RFC PATCH 14/16] irq: Add support for core-wide protection of IRQ and softirq
In-Reply-To: <ed837e01-043b-e19b-293c-30d44df6f3a8@linux.intel.com>
References: <cover.1593530334.git.vpillai@digitalocean.com> <c783b3890b6df669a72c7c4a3012950d009b8034.1593530334.git.vpillai@digitalocean.com> <ed837e01-043b-e19b-293c-30d44df6f3a8@linux.intel.com>
Date:   Sat, 18 Jul 2020 01:37:50 +0200
Message-ID: <87y2nhpvap.fsf@nanos.tec.linutronix.de>
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"Li, Aubrey" <aubrey.li@linux.intel.com> writes:
> On 2020/7/1 5:32, Vineeth Remanan Pillai wrote:
>
> We saw a lot of soft lockups on the screen when we tested v6.
>
> [  186.527883] watchdog: BUG: soft lockup - CPU#86 stuck for 22s! [uperf:5551]
> [  186.535884] watchdog: BUG: soft lockup - CPU#87 stuck for 22s! [uperf:5444]
> [  186.555883] watchdog: BUG: soft lockup - CPU#89 stuck for 22s! [uperf:5547]
> [  187.547884] rcu: INFO: rcu_sched self-detected stall on CPU
> [  187.553760] rcu: 	40-....: (14997 ticks this GP) idle=49a/1/0x4000000000000002 softirq=1711/1711 fqs=7279 
> [  187.564685] NMI watchdog: Watchdog detected hard LOCKUP on cpu 14
> [  187.564723] NMI watchdog: Watchdog detected hard LOCKUP on cpu 38
>
> The problem is gone when we reverted this patch. We are running multiple
> uperf threads(equal to cpu number) in a cgroup with coresched enabled.
> This is 100% reproducible on our side.

ROTFL. I just predicted that from staring at the patch ....