linux-kernel - Re: DRM Error on Acer Aspire One

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Date:	Tue, 11 May 2010 12:10:01 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Chris Wilson <chris@...is-wilson.co.uk>
Cc:	Jaswinder Singh Rajput <jaswinderlinux@...il.com>,
	dri-devel@...ts.freedesktop.org, Dave Airlie <airlied@...ux.ie>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Keith Packard <keithp@...thp.com>,
	Eric Anholt <eric@...olt.net>, Ingo Molnar <mingo@...e.hu>
Subject: Re: DRM Error on Acer Aspire One

On Tue, 11 May 2010 19:52:31 +0100
Chris Wilson <chris@...is-wilson.co.uk> wrote:

> On Tue, 11 May 2010 11:35:55 -0400, Andrew Morton <akpm@...ux-foundation.org> wrote:
> > No, io_mapping_map_atomic_wc() cannot be used from [soft]irq context:
> > it hardwires use of KM_USER0.  I suggest that io_mapping_create_wc(),
> > io_mapping_map_atomic_wc() etc be changed so that the caller passes in the
> > KM_foo kmap slot index.
> 
> Argh, sorry for the noise, read the mail in the wrong order. Thanks for
> the review. It would be sensible to go with your simpler patch whilst
> io_mapping_map_atomic_wc() is improved.

OK.  I'll be sending a bunch of fixes Linuswards in an hour or two.  
Should I include this?


Subject: drivers/gpu/drm/i915/i915_irq.c:i915_error_object_create(): use correct kmap-atomic slot
From: Andrew Morton <akpm@...ux-foundation.org>

i915_error_object_create() is called from the timer interrupt and hence
can corrupt the KM_USER0 slot.  Use KM_IRQ0 instead.

Reported-by: Jaswinder Singh Rajput <jaswinderlinux@...il.com>
Tested-by: Jaswinder Singh Rajput <jaswinderlinux@...il.com>
Cc: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Dave Airlie <airlied@...ux.ie>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 drivers/gpu/drm/i915/i915_irq.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff -puN drivers/gpu/drm/i915/i915_irq.c~drivers-gpu-drm-i915-i915_irqc-i915_error_object_create-use-correct-kmap-atomic-slot drivers/gpu/drm/i915/i915_irq.c
--- a/drivers/gpu/drm/i915/i915_irq.c~drivers-gpu-drm-i915-i915_irqc-i915_error_object_create-use-correct-kmap-atomic-slot
+++ a/drivers/gpu/drm/i915/i915_irq.c
@@ -461,11 +461,15 @@ i915_error_object_create(struct drm_devi
 
 	for (page = 0; page < page_count; page++) {
 		void *s, *d = kmalloc(PAGE_SIZE, GFP_ATOMIC);
+		unsigned long flags;
+
 		if (d == NULL)
 			goto unwind;
-		s = kmap_atomic(src_priv->pages[page], KM_USER0);
+		local_irq_save(flags);
+		s = kmap_atomic(src_priv->pages[page], KM_IRQ0);
 		memcpy(d, s, PAGE_SIZE);
-		kunmap_atomic(s, KM_USER0);
+		kunmap_atomic(s, KM_IRQ0);
+		local_irq_restore(flags);
 		dst->pages[page] = d;
 	}
 	dst->page_count = page_count;
_

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