linux-kernel - Re: [BUG] completely bonkers use of set_need_resched + VM_FAULT

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Message-ID: <alpine.DEB.2.02.1309122238430.4089@ionos.tec.linutronix.de>
Date:	Thu, 12 Sep 2013 22:39:27 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Daniel Vetter <daniel.vetter@...ll.ch>
cc:	Peter Zijlstra <peterz@...radead.org>,
	Dave Airlie <airlied@...ux.ie>,
	Maarten Lankhorst <maarten.lankhorst@...onical.com>,
	Thomas Hellstrom <thellstrom@...are.com>,
	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [BUG] completely bonkers use of set_need_resched +
 VM_FAULT_NOPAGE

On Thu, 12 Sep 2013, Daniel Vetter wrote:

> On Thu, Sep 12, 2013 at 10:20 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> >> I think for ttm drivers it's just execbuf being exploitable. But on
> >> drm/i915 we've
> >> had the same issue with the pwrite/pread ioctls, so a simple
> >> glBufferData(glMap) kind of recursion from gl clients blew the kernel
> >> to pieces ...
> >
> > And the only answer you folks came up with is set_need_resched() and
> > yield()? Oh well....
> 
> The yield was for a different lifelock, and that one is also fixed by
> now. The fault handler deadlock was fixed in the usual "drop locks and
> jump into slowpath" fasion, at least in drm/i915.

So we can remove that whole yield/set_need_resched() mess completely ?

Thanks,

	tglx
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