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drm/i915/gem: Split eb_vma into its own allocation
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Use a separate array allocation for the execbuf vma, so that we can
track their lifetime independently from the copy of the user arguments.
With luck, this has a secondary benefit of splitting the malloc size to
within reason and avoid vmalloc. The downside is that we might require
two separate vmallocs -- but much less likely.

In the process, this prevents a memory leak on the ww_mutex error
unwind.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/1390
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200330133710.14385-1-chris@chris-wilson.co.uk
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Chris Wilson committed Mar 30, 2020
1 parent d7d50f8 commit 0f1dd02
Showing 1 changed file with 73 additions and 58 deletions.
131 changes: 73 additions & 58 deletions drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,11 @@ struct eb_vma {
u32 handle;
};

struct eb_vma_array {
struct kref kref;
struct eb_vma vma[];
};

enum {
FORCE_CPU_RELOC = 1,
FORCE_GTT_RELOC,
Expand All @@ -52,7 +57,6 @@ enum {
#define __EXEC_OBJECT_NEEDS_MAP BIT(29)
#define __EXEC_OBJECT_NEEDS_BIAS BIT(28)
#define __EXEC_OBJECT_INTERNAL_FLAGS (~0u << 28) /* all of the above */
#define __EXEC_OBJECT_RESERVED (__EXEC_OBJECT_HAS_PIN | __EXEC_OBJECT_HAS_FENCE)

#define __EXEC_HAS_RELOC BIT(31)
#define __EXEC_INTERNAL_FLAGS (~0u << 31)
Expand Down Expand Up @@ -283,6 +287,7 @@ struct i915_execbuffer {
*/
int lut_size;
struct hlist_head *buckets; /** ht for relocation handles */
struct eb_vma_array *array;
};

static inline bool eb_use_cmdparser(const struct i915_execbuffer *eb)
Expand All @@ -292,8 +297,62 @@ static inline bool eb_use_cmdparser(const struct i915_execbuffer *eb)
eb->args->batch_len);
}

static struct eb_vma_array *eb_vma_array_create(unsigned int count)
{
struct eb_vma_array *arr;

arr = kvmalloc(struct_size(arr, vma, count), GFP_KERNEL | __GFP_NOWARN);
if (!arr)
return NULL;

kref_init(&arr->kref);
arr->vma[0].vma = NULL;

return arr;
}

static inline void eb_unreserve_vma(struct eb_vma *ev)
{
struct i915_vma *vma = ev->vma;

if (unlikely(ev->flags & __EXEC_OBJECT_HAS_FENCE))
__i915_vma_unpin_fence(vma);

if (ev->flags & __EXEC_OBJECT_HAS_PIN)
__i915_vma_unpin(vma);

ev->flags &= ~(__EXEC_OBJECT_HAS_PIN |
__EXEC_OBJECT_HAS_FENCE);
}

static void eb_vma_array_destroy(struct kref *kref)
{
struct eb_vma_array *arr = container_of(kref, typeof(*arr), kref);
struct eb_vma *ev = arr->vma;

while (ev->vma) {
eb_unreserve_vma(ev);
i915_vma_put(ev->vma);
ev++;
}

kvfree(arr);
}

static void eb_vma_array_put(struct eb_vma_array *arr)
{
kref_put(&arr->kref, eb_vma_array_destroy);
}

static int eb_create(struct i915_execbuffer *eb)
{
/* Allocate an extra slot for use by the command parser + sentinel */
eb->array = eb_vma_array_create(eb->buffer_count + 2);
if (!eb->array)
return -ENOMEM;

eb->vma = eb->array->vma;

if (!(eb->args->flags & I915_EXEC_HANDLE_LUT)) {
unsigned int size = 1 + ilog2(eb->buffer_count);

Expand Down Expand Up @@ -327,8 +386,10 @@ static int eb_create(struct i915_execbuffer *eb)
break;
} while (--size);

if (unlikely(!size))
if (unlikely(!size)) {
eb_vma_array_put(eb->array);
return -ENOMEM;
}

eb->lut_size = size;
} else {
Expand Down Expand Up @@ -402,26 +463,6 @@ eb_pin_vma(struct i915_execbuffer *eb,
return !eb_vma_misplaced(entry, vma, ev->flags);
}

static inline void __eb_unreserve_vma(struct i915_vma *vma, unsigned int flags)
{
GEM_BUG_ON(!(flags & __EXEC_OBJECT_HAS_PIN));

if (unlikely(flags & __EXEC_OBJECT_HAS_FENCE))
__i915_vma_unpin_fence(vma);

__i915_vma_unpin(vma);
}

static inline void
eb_unreserve_vma(struct eb_vma *ev)
{
if (!(ev->flags & __EXEC_OBJECT_HAS_PIN))
return;

__eb_unreserve_vma(ev->vma, ev->flags);
ev->flags &= ~__EXEC_OBJECT_RESERVED;
}

static int
eb_validate_vma(struct i915_execbuffer *eb,
struct drm_i915_gem_exec_object2 *entry,
Expand Down Expand Up @@ -863,31 +904,13 @@ eb_get_vma(const struct i915_execbuffer *eb, unsigned long handle)
}
}

static void eb_release_vmas(const struct i915_execbuffer *eb)
{
const unsigned int count = eb->buffer_count;
unsigned int i;

for (i = 0; i < count; i++) {
struct eb_vma *ev = &eb->vma[i];
struct i915_vma *vma = ev->vma;

if (!vma)
break;

eb->vma[i].vma = NULL;

if (ev->flags & __EXEC_OBJECT_HAS_PIN)
__eb_unreserve_vma(vma, ev->flags);

i915_vma_put(vma);
}
}

static void eb_destroy(const struct i915_execbuffer *eb)
{
GEM_BUG_ON(eb->reloc_cache.rq);

if (eb->array)
eb_vma_array_put(eb->array);

if (eb->lut_size > 0)
kfree(eb->buckets);
}
Expand Down Expand Up @@ -1635,19 +1658,15 @@ static int eb_move_to_gpu(struct i915_execbuffer *eb)
err = i915_vma_move_to_active(vma, eb->request, flags);

i915_vma_unlock(vma);

__eb_unreserve_vma(vma, flags);
i915_vma_put(vma);

ev->vma = NULL;
eb_unreserve_vma(ev);
}
ww_acquire_fini(&acquire);

eb_vma_array_put(fetch_and_zero(&eb->array));

if (unlikely(err))
goto err_skip;

eb->exec = NULL;

/* Unconditionally flush any chipset caches (for streaming writes). */
intel_gt_chipset_flush(eb->engine->gt);
return 0;
Expand Down Expand Up @@ -1899,6 +1918,7 @@ static int eb_parse(struct i915_execbuffer *eb)
eb->vma[eb->buffer_count].vma = i915_vma_get(shadow);
eb->vma[eb->buffer_count].flags = __EXEC_OBJECT_HAS_PIN;
eb->batch = &eb->vma[eb->buffer_count++];
eb->vma[eb->buffer_count].vma = NULL;

eb->trampoline = trampoline;
eb->batch_start_offset = 0;
Expand Down Expand Up @@ -2422,8 +2442,6 @@ i915_gem_do_execbuffer(struct drm_device *dev,
args->flags |= __EXEC_HAS_RELOC;

eb.exec = exec;
eb.vma = (struct eb_vma *)(exec + args->buffer_count + 1);
eb.vma[0].vma = NULL;

eb.invalid_flags = __EXEC_OBJECT_UNKNOWN_FLAGS;
reloc_cache_init(&eb.reloc_cache, eb.i915);
Expand Down Expand Up @@ -2630,8 +2648,6 @@ i915_gem_do_execbuffer(struct drm_device *dev,
if (batch->private)
intel_engine_pool_put(batch->private);
err_vma:
if (eb.exec)
eb_release_vmas(&eb);
if (eb.trampoline)
i915_vma_unpin(eb.trampoline);
eb_unpin_engine(&eb);
Expand All @@ -2651,7 +2667,7 @@ i915_gem_do_execbuffer(struct drm_device *dev,

static size_t eb_element_size(void)
{
return sizeof(struct drm_i915_gem_exec_object2) + sizeof(struct eb_vma);
return sizeof(struct drm_i915_gem_exec_object2);
}

static bool check_buffer_count(size_t count)
Expand Down Expand Up @@ -2707,7 +2723,7 @@ i915_gem_execbuffer_ioctl(struct drm_device *dev, void *data,
/* Copy in the exec list from userland */
exec_list = kvmalloc_array(count, sizeof(*exec_list),
__GFP_NOWARN | GFP_KERNEL);
exec2_list = kvmalloc_array(count + 1, eb_element_size(),
exec2_list = kvmalloc_array(count, eb_element_size(),
__GFP_NOWARN | GFP_KERNEL);
if (exec_list == NULL || exec2_list == NULL) {
drm_dbg(&i915->drm,
Expand Down Expand Up @@ -2785,8 +2801,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
if (err)
return err;

/* Allocate an extra slot for use by the command parser */
exec2_list = kvmalloc_array(count + 1, eb_element_size(),
exec2_list = kvmalloc_array(count, eb_element_size(),
__GFP_NOWARN | GFP_KERNEL);
if (exec2_list == NULL) {
drm_dbg(&i915->drm, "Failed to allocate exec list for %zd buffers\n",
Expand Down

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