[PATCH] drm/gem: remove obsolete BUG_ON

David Herrmann dh.herrmann at gmail.com
Sun May 25 05:36:30 PDT 2014


On Wed, May 21, 2014 at 3:17 PM, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Wed, May 21, 2014 at 02:16:26PM +0200, David Herrmann wrote:
>> The shmem subsystem supports relocating pages on swap-in in case it was
>> loaded into the wrong zone. This was implemented 2 years ago in:
>>     commit bde05d1ccd512696b09db9dd2e5f33ad19152605
>>     Author: Hugh Dickins <hughd at google.com>
>>     Date:   Tue May 29 15:06:38 2012 -0700
>>         shmem: replace page if mapping excludes its zone
>> If a driver requires pages to be in a specific zone, they _must_ set the
>> correct GFP flags (like __GFP_DMA32) in mapping_gfp_mask(mapping). shmem
>> will make sure that any page leaving the swap-cache is located in a
>> compatible zone.
>> Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
> Imo the BUG_ON is nice since we want to make sure this never blows up. We
> have a similar one in i915_gem.c since we do have platforms with 32bit
> limits that support more than 4G or ram.
> Imo better to update the comment and state that this is fixed now, but
> better be paranoid.

Ok, I've kept the BUG_ON. I've also appended some more patches that
clean-up the shmem handling. v2 is on the list.


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