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drm/i915: Recreate internal objects with single page segments if dmar fails

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If we fail to dma-map the object, the most common cause is lack of space
inside the SW-IOTLB due to fragmentation. If we recreate the_sg_table
using segments of PAGE_SIZE (and single page allocations), we may succeed
in remapping the scatterlist.

First became a significant problem for the mock selftests after commit
5584f1b1d7 ("drm/i915: fix i915 running as dom0 under Xen") increased
the max_order.

Fixes: 920cf41949 ("drm/i915: Introduce an internal allocator for disposable private objects")
Fixes: 5584f1b1d7 ("drm/i915: fix i915 running as dom0 under Xen")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170202132721.12711-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.10-rc1+
This commit is contained in:
Chris Wilson 2017-02-02 13:27:21 +00:00
parent 3aac4acb89
commit bb96dcf583
1 changed files with 23 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
drivers/gpu/drm/i915/i915_gem_internal.c
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@ -48,24 +48,12 @@ static struct sg_table *
i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
{
struct drm_i915_private *i915 = to_i915(obj->base.dev);
unsigned int npages = obj->base.size / PAGE_SIZE;
struct sg_table *st;
struct scatterlist *sg;
unsigned int npages;
int max_order;
gfp_t gfp;
st = kmalloc(sizeof(*st), GFP_KERNEL);
if (!st)
return ERR_PTR(-ENOMEM);
if (sg_alloc_table(st, npages, GFP_KERNEL)) {
kfree(st);
return ERR_PTR(-ENOMEM);
}
sg = st->sgl;
st->nents = 0;
max_order = MAX_ORDER;
#ifdef CONFIG_SWIOTLB
if (swiotlb_nr_tbl()) {
@ -87,6 +75,20 @@ i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
gfp |= __GFP_DMA32;
}
create_st:
st = kmalloc(sizeof(*st), GFP_KERNEL);
if (!st)
return ERR_PTR(-ENOMEM);
npages = obj->base.size / PAGE_SIZE;
if (sg_alloc_table(st, npages, GFP_KERNEL)) {
kfree(st);
return ERR_PTR(-ENOMEM);
}
sg = st->sgl;
st->nents = 0;
do {
int order = min(fls(npages) - 1, max_order);
struct page *page;
@ -114,8 +116,15 @@ i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
sg = __sg_next(sg);
} while (1);
if (i915_gem_gtt_prepare_pages(obj, st))
if (i915_gem_gtt_prepare_pages(obj, st)) {
/* Failed to dma-map try again with single page sg segments */
if (get_order(st->sgl->length)) {
internal_free_pages(st);
max_order = 0;
goto create_st;
}
goto err;
}
/* Mark the pages as dontneed whilst they are still pinned. As soon
* as they are unpinned they are allowed to be reaped by the shrinker,