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Date: Thu, 22 Sep 2016 09:44:20 +0900
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Petr Mladek <pmladek@suse.com>, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Byungchul Park <byungchul.park@lge.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Luca Abeni <luca.abeni@unitn.it>, Rik van Riel <riel@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Wanpeng Li <wanpeng.li@hotmail.com>, Yuyang Du <yuyang.du@intel.com>,
        Jan Kara <jack@suse.cz>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        linux-kernel@vger.kernel.org, Mel Gorman <mgorman@techsingularity.net>,
        Mike Galbraith <umgwanakikbuti@gmail.com>
Subject: Re: [PATCH v2 7/7] sched/core: Add debug code to catch missing
 update_rq_clock()
Message-ID: <20160922004420.GB701@swordfish>
References: <20160921133813.31976-1-matt@codeblueprint.co.uk>
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 <20160921155826.GB8408@pathway.suse.cz>
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Hello,

On (09/21/16 20:08), Matt Fleming wrote:
> On Wed, 21 Sep, at 05:58:27PM, Petr Mladek wrote:
> > 
> > I am not sure how the above call chain is realistic. But adding
> > WARN_ON() into the scheduler paths is risky in general.
> 
> It's not clear to me why this should be the case. WARN_ON() calls have
> existed in the scheduler paths since forever.
> 
> If the new async printk patches make that impossible then surely they
> need fixing, not the scheduler?

it's not specific to async printk, because printk already invokes scheduler
via semaphore up().

	-ss