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Revert "drm/i915/lmem: Limit block size to 4G" 

Mixing I915_ALLOC_CONTIGUOUS and I915_ALLOC_MAX_SEGMENT_SIZE fared
badly. The two directives conflict, with the contiguous request setting
the min_order to the full size of the object, and the max-segment-size
setting the max_order to the limit of the DMA mapper. This results in a
situation where max_order < min_order, causing our sanity checks to
fail.

Instead of limiting the buddy block size, in the previous patch we split
the oversized buddy into multiple scatterlist elements.

Fixes: d2cf0125d4 ("drm/i915/lmem: Limit block size to 4G")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201202173444.14903-2-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2020-12-02 17:34:44 +00:00
parent a2843b3bd1
commit 7d1a31e128
4 changed files with 26 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/gpu/drm/i915/gem/i915_gem_region.c
View File

@ -43,7 +43,7 @@ i915_gem_object_get_pages_buddy(struct drm_i915_gem_object *obj)
return -ENOMEM;
}
flags = I915_ALLOC_MIN_PAGE_SIZE | I915_ALLOC_MAX_SEGMENT_SIZE;
flags = I915_ALLOC_MIN_PAGE_SIZE;
if (obj->flags & I915_BO_ALLOC_CONTIGUOUS)
flags |= I915_ALLOC_CONTIGUOUS;

18
drivers/gpu/drm/i915/intel_memory_region.c
View File

@ -72,7 +72,6 @@ __intel_memory_region_get_pages_buddy(struct intel_memory_region *mem,
struct list_head *blocks)
{
unsigned int min_order = 0;
unsigned int max_order;
unsigned long n_pages;
GEM_BUG_ON(!IS_ALIGNED(size, mem->mm.chunk_size));
@ -93,28 +92,13 @@ __intel_memory_region_get_pages_buddy(struct intel_memory_region *mem,
n_pages = size >> ilog2(mem->mm.chunk_size);
/*
* If we going to feed this into an sg list we should limit the block
* sizes such that we don't exceed the i915_sg_segment_size().
*/
if (flags & I915_ALLOC_MAX_SEGMENT_SIZE) {
unsigned int max_segment = i915_sg_segment_size();
if (GEM_WARN_ON(max_segment < mem->mm.chunk_size))
max_order = 0;
else
max_order = ilog2(max_segment) - ilog2(mem->mm.chunk_size);
} else {
max_order = mem->mm.max_order;
}
mutex_lock(&mem->mm_lock);
do {
struct i915_buddy_block *block;
unsigned int order;
order = min_t(u32, fls(n_pages) - 1, max_order);
order = fls(n_pages) - 1;
GEM_BUG_ON(order > mem->mm.max_order);
GEM_BUG_ON(order < min_order);

5
drivers/gpu/drm/i915/intel_memory_region.h
View File

@ -44,9 +44,8 @@ enum intel_region_id {
#define MEMORY_TYPE_FROM_REGION(r) (ilog2((r) >> INTEL_MEMORY_TYPE_SHIFT))
#define MEMORY_INSTANCE_FROM_REGION(r) (ilog2((r) & 0xffff))
#define I915_ALLOC_MIN_PAGE_SIZE BIT(0)
#define I915_ALLOC_CONTIGUOUS BIT(1)
#define I915_ALLOC_MAX_SEGMENT_SIZE BIT(2)
#define I915_ALLOC_MIN_PAGE_SIZE BIT(0)
#define I915_ALLOC_CONTIGUOUS BIT(1)
#define for_each_memory_region(mr, i915, id) \
for (id = 0; id < ARRAY_SIZE((i915)->mm.regions); id++) \

33
drivers/gpu/drm/i915/selftests/intel_memory_region.c
View File

@ -356,21 +356,21 @@ out_put:
static int igt_mock_max_segment(void *arg)
{
const unsigned int max_segment = i915_sg_segment_size();
struct intel_memory_region *mem = arg;
struct drm_i915_private *i915 = mem->i915;
struct drm_i915_gem_object *obj;
struct i915_buddy_block *block;
struct scatterlist *sg;
LIST_HEAD(objects);
u64 size;
int err = 0;
/*
* The size of block are only limited by the largest power-of-two that
* will fit in the region size, but to construct an object we also
* require feeding it into an sg list, where the upper limit of the sg
* entry is at most UINT_MAX, therefore when allocating with
* I915_ALLOC_MAX_SEGMENT_SIZE we shouldn't see blocks larger than
* i915_sg_segment_size().
* While we may create very large contiguous blocks, we may need
* to break those down for consumption elsewhere. In particular,
* dma-mapping with scatterlist elements have an implicit limit of
* UINT_MAX on each element.
*/
size = SZ_8G;
@ -384,12 +384,23 @@ static int igt_mock_max_segment(void *arg)
goto out_put;
}
err = -EINVAL;
list_for_each_entry(block, &obj->mm.blocks, link) {
if (i915_buddy_block_size(&mem->mm, block) > i915_sg_segment_size()) {
pr_err("%s found block size(%llu) larger than max sg_segment_size(%u)",
__func__,
i915_buddy_block_size(&mem->mm, block),
i915_sg_segment_size());
if (i915_buddy_block_size(&mem->mm, block) > max_segment) {
err = 0;
break;
}
}
if (err) {
pr_err("%s: Failed to create a huge contiguous block\n",
__func__);
goto out_close;
}
for (sg = obj->mm.pages->sgl; sg; sg = sg_next(sg)) {
if (sg->length > max_segment) {
pr_err("%s: Created an oversized scatterlist entry, %u > %u\n",
__func__, sg->length, max_segment);
err = -EINVAL;
goto out_close;
}