Messages in this thread Patch in this message | | | Date | Tue, 26 May 2009 23:55:50 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: [PATCH] drm: i915: ensure objects are allocated below 4GB on PAE |
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On Tue, 26 May 2009, Kyle McMartin wrote: > From: Kyle McMartin <kyle@redhat.com> > > Ensure we allocate GEM objects below 4GB on PAE machines, otherwise > misery ensues. This patch is based on a patch found on dri-devel by > Shaohua Li, but Keith P. expressed reticence that the changes unfairly > penalized other hardware. > > (The mm/shmem.c hunk is necessary to ensure the DMA32 flag isn't used > by the slab allocator via radix_tree_preload, which will hit a > WARN_ON.) > > Signed-off-by: Kyle McMartin <kyle@redhat.com>
I'm confused: I thought GFP_DMA32 only applies on x86_64: my 32-bit PAE machine with (slightly!) > 4GB shows no ZONE_DMA32. Does this patch perhaps depend on another, to enable DMA32 on 32-bit PAE, or am I just in a muddle?
Regarding the mm/shmem.c hunk: > - error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); > + error = radix_tree_preload(gfp & ~(__GFP_HIGHMEM|__GFP_DMA32));
Yes, that would make sense. I dislike it, but my dislike is no reason to hold you up: what it ought to say is error = radix_tree_preload(gfp & GFP_RECLAIM_MASK); and similarly the several other (gfp & ~__GFP_HIGHMEM)s to be found in nearby files: it's just an accident of history that nobody has hit this issue with __GFP_DMA or __GFP_DMA32 before. I intended to change these months ago, my slowness is no reason to delay you.
Hugh
> --- > > We're shipping a variant of this in Fedora 11 to fix a myriad of bugs on > PAE hardware. > > cheers, Kyle > > --- > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > index 4984aa8..ae52edc 100644 > --- a/drivers/gpu/drm/drm_gem.c > +++ b/drivers/gpu/drm/drm_gem.c > @@ -142,6 +142,9 @@ drm_gem_object_alloc(struct drm_device *dev, size_t size) > return NULL; > } > > + if (dev->gem_flags) > + mapping_set_gfp_mask(obj->filp->f_mapping, dev->gem_flags); > + > kref_init(&obj->refcount); > kref_init(&obj->handlecount); > obj->size = size; > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c > index 53d5445..c89ae3d 100644 > --- a/drivers/gpu/drm/i915/i915_dma.c > +++ b/drivers/gpu/drm/i915/i915_dma.c > @@ -1153,12 +1153,12 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) > } > > #ifdef CONFIG_HIGHMEM64G > - /* don't enable GEM on PAE - needs agp + set_memory_* interface fixes */ > - dev_priv->has_gem = 0; > -#else > + /* avoid allocating buffers above 4GB on PAE */ > + dev->gem_flags = GFP_USER | GFP_DMA32; > +#endif > + > /* enable GEM by default */ > dev_priv->has_gem = 1; > -#endif > > dev->driver->get_vblank_counter = i915_get_vblank_counter; > if (IS_GM45(dev)) > diff --git a/include/drm/drmP.h b/include/drm/drmP.h > index c8c4221..3744c1f 100644 > --- a/include/drm/drmP.h > +++ b/include/drm/drmP.h > @@ -1019,6 +1019,7 @@ struct drm_device { > uint32_t gtt_total; > uint32_t invalidate_domains; /* domains pending invalidation */ > uint32_t flush_domains; /* domains pending flush */ > + gfp_t gem_flags; /* object allocation flags */ > /*@} */ > > }; > diff --git a/mm/shmem.c b/mm/shmem.c > index b25f95c..e615887 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1241,7 +1241,7 @@ repeat: > * Try to preload while we can wait, to not make a habit of > * draining atomic reserves; but don't latch on to this cpu. > */ > - error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); > + error = radix_tree_preload(gfp & ~(__GFP_HIGHMEM|__GFP_DMA32)); > if (error) > goto failed; > radix_tree_preload_end();
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