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From: Guenter Roeck <linux@roeck-us.net>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Intel graphics driver community testing & development
	<intel-gfx@lists.freedesktop.org>
Subject: Re: [CI, v3, 1/2] drm/i915: Prevent a race during I915_GEM_MMAP ioctl with WC set
Date: Thu, 28 Feb 2019 14:27:35 -0800	[thread overview]
Message-ID: <20190228222735.GA18025@roeck-us.net> (raw)
In-Reply-To: <155139230746.5847.12709934432272887200@skylake-alporthouse-com>

On Thu, Feb 28, 2019 at 10:18:32PM +0000, Chris Wilson wrote:
> 
> If you have userspace that is broken, we need to fix it. We can get away
> with quietly changing ABI only so long as nobody notices. It sounds like
> you have some userspace that will break if you updated the kernel; ergo
> we have a problem.
> 
> We just need that as a clear statement so that we have the user impact
> recorded.

Yes, it does break our userspace code. I fixed the problem in our kernels
with the following patch:

-	return vma->vm_start == addr && (vma->vm_end - vma->vm_start) == size;
+	return vma->vm_start == addr && (vma->vm_end - vma->vm_start) == roundup(size, PAGE_SIZE);

Guenter
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  reply	other threads:[~2019-02-28 22:27 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-07  8:54 [CI v3 1/2] drm/i915: Prevent a race during I915_GEM_MMAP ioctl with WC set Joonas Lahtinen
2019-02-07  8:54 ` [CI v3 2/2] drm/i915: Handle vm_mmap error " Joonas Lahtinen
2019-02-07  9:29 ` ✓ Fi.CI.BAT: success for series starting with [CI,v3,1/2] drm/i915: Prevent a race " Patchwork
2019-02-07 11:52 ` ✓ Fi.CI.IGT: " Patchwork
2019-02-28 19:12 ` [CI, v3, 1/2] " Guenter Roeck
2019-02-28 21:32   ` Guenter Roeck
2019-02-28 21:48     ` Chris Wilson
2019-02-28 21:57     ` Guenter Roeck
2019-02-28 22:01       ` Chris Wilson
2019-02-28 22:11         ` Guenter Roeck
2019-02-28 22:18           ` Chris Wilson
2019-02-28 22:27             ` Guenter Roeck [this message]
2019-02-28 22:34               ` Chris Wilson
2019-03-01  0:15                 ` Guenter Roeck

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