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Date: Wed, 20 Jan 2016 21:01:11 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Davidlohr Bueso <dave@stgolabs.net>
cc: Mel Gorman <mgorman@techsingularity.net>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Chris Mason <clm@fb.com>, Darren Hart <dvhart@linux.intel.com>,
        linux-kernel@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH v3] futex: Remove requirement for lock_page in
In-Reply-To: <20160120195523.GF27825@linux-uzut.site>
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References: <1453249853-1184-1-git-send-email-dave@stgolabs.net> <20160120195523.GF27825@linux-uzut.site>
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On Wed, 20 Jan 2016, Davidlohr Bueso wrote:
> On Tue, 19 Jan 2016, Bueso wrote:
> > +
> > +		/* Should be impossible but lets be paranoid for now */
> > +		BUG_ON(inode->i_mapping != mapping);
> 
> Hmm, do we want to transform this into an if and do rcu unlock and then just
> call BUG()? I't doesn't matter at this point _anyway_, but it would be the
> right
> thing to do, no?

The better solution is to err out gracefully.

    	   if (WARN_ON_ONCE(inode->i_mapping != mapping) {
	      	   err = -EFAULT;
		   rcu_read_unlock();
		   goto out;
    	   }

Hmm?

Thanks,

	tglx