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Merged
alexreinking merged 3 commits into from
Jul 28, 2026
+70 −65
Merged

Hardening region allocator #9224

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fa49d88
[vulkan] Harden split_block_region against mis-sized splits
johningve Jul 20, 2026
1315d7c
[vulkan] Invalidate stale region handle when coalescing into prev region
johningve Jul 20, 2026
7056659
[vulkan] Verify the region handle-size invariant in allocator tests
johningve Jul 20, 2026
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88 changes: 39 additions & 49 deletions src/runtime/internal/region_allocator.h
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,9 @@ class RegionAllocator {
// Invokes the deallocation callback to free memory for the block region
int free_block_region(void *user_context, BlockRegion *region);

// Deallocate only if the region is unused.
int deallocate_block_region_if_unused(void *user_context, BlockRegion *region);

// Returns true if the given block region is the last region in the list
bool is_last_block_region(void *user_context, const BlockRegion *region) const;

Expand Down Expand Up @@ -389,24 +392,11 @@ bool RegionAllocator::can_coalesce(const BlockRegion *block_region) const {
}

BlockRegion *RegionAllocator::coalesce_block_regions(void *user_context, BlockRegion *block_region) {

if ((block_region->usage_count == 0) && (block_region->memory.handle != nullptr)) {
#ifdef DEBUG_RUNTIME_INTERNAL
debug(user_context) << "RegionAllocator: Freeing unused region to coalesce ("
<< "block_ptr=" << (void *)block_region->block_ptr << " "
<< "block_region=" << (void *)block_region << " "
<< "memory_size=" << (uint32_t)(block_region->memory.allocation.size) << " "
<< "block_reserved=" << (uint32_t)block->reserved << " "
<< ")";
#endif
halide_abort_if_false(user_context, allocators.region.deallocate != nullptr);
MemoryRegion *memory_region = &(block_region->memory);
allocators.region.deallocate(user_context, memory_region);
block_region->memory.handle = nullptr;
}
deallocate_block_region_if_unused(user_context, block_region);

BlockRegion *prev_region = block_region->prev_ptr;
if (is_available(prev_region) && (prev_region != block_region)) {
deallocate_block_region_if_unused(user_context, prev_region);

#ifdef DEBUG_RUNTIME_INTERNAL
debug(user_context) << "RegionAllocator: Coalescing "
Expand Down Expand Up @@ -448,29 +438,18 @@ bool RegionAllocator::can_split(const BlockRegion *block_region, const MemoryReq
}

BlockRegion *RegionAllocator::split_block_region(void *user_context, BlockRegion *block_region, const MemoryRequest &request) {
const size_t original_size = block_region->memory.allocation.size;
const size_t original_offset = block_region->memory.allocation.offset;

if ((block_region->usage_count == 0) && (block_region->memory.handle != nullptr)) {
#ifdef DEBUG_RUNTIME_INTERNAL
debug(user_context) << "RegionAllocator: Split deallocate region ("
<< "block_ptr=" << (void *)block_region->block_ptr << " "
<< "block_region=" << (void *)block_region << " "
<< "memory_size=" << (uint32_t)(block_region->memory.allocation.size) << " "
<< "block_reserved=" << (uint32_t)block_region->block_ptr->reserved << " "
<< ")";
#endif
halide_abort_if_false(user_context, allocators.region.deallocate != nullptr);
MemoryRegion *memory_region = &(block_region->memory);
allocators.region.deallocate(user_context, memory_region);
block_region->memory.handle = nullptr;
}
deallocate_block_region_if_unused(user_context, block_region);

MemoryRequest split_request = request;
split_request.size = block_region->memory.allocation.size - request.size;
split_request.offset = block_region->memory.allocation.offset + request.size;
split_request.size = original_size - request.size;
split_request.offset = original_offset + request.size;

#ifdef DEBUG_RUNTIME_INTERNAL
debug(user_context) << "RegionAllocator: Splitting "
<< "current region (offset=" << (int32_t)block_region->memory.allocation.offset << " size=" << (int32_t)(block_region->memory.allocation.size) << " bytes) "
<< "current region (offset=" << (int32_t)original_offset << " size=" << (int32_t)(original_size) << " bytes) "
<< "to create empty region (offset=" << (int32_t)split_request.offset << " size=" << (int32_t)(split_request.size) << " bytes)";
#endif
BlockRegion *next_region = block_region->next_ptr;
Expand All @@ -483,7 +462,13 @@ BlockRegion *RegionAllocator::split_block_region(void *user_context, BlockRegion
}
empty_region->prev_ptr = block_region;
block_region->next_ptr = empty_region;
block_region->memory.allocation.size -= empty_region->memory.allocation.size;

// Derive the allocated region's size from the empty region's conformed offset;
// subtracting the empty region's size would shrink this region below the request
// whenever conforming the empty region adjusted its offset or size.
block_region->memory.allocation.size = empty_region->memory.allocation.offset - original_offset;
halide_abort_if_false(user_context, block_region->memory.allocation.size >= request.size);
halide_abort_if_false(user_context, empty_region->memory.allocation.offset + empty_region->memory.allocation.size <= original_offset + original_size);
return empty_region;
}

Expand Down Expand Up @@ -651,27 +636,32 @@ int RegionAllocator::free_block_region(void *user_context, BlockRegion *block_re
<< "usage_count=" << (uint32_t)block_region->usage_count << " "
<< "block_reserved=" << (uint32_t)block->reserved << ")";
#endif
int error_code = 0;
if ((block_region->usage_count == 0) && (block_region->memory.handle != nullptr)) {
#ifdef DEBUG_RUNTIME_INTERNAL
debug(user_context) << " deallocating region ("
<< "block_ptr=" << (void *)block_region->block_ptr << " "
<< "block_region=" << (void *)block_region << " "
<< "memory_size=" << (uint32_t)(block_region->memory.allocation.size) << " "
<< "block_reserved=" << (uint32_t)block->reserved << " "
<< ")";
#endif
// NOTE: Deallocate but leave memory size as is, so that coalesce can compute region merging sizes
halide_abort_if_false(user_context, allocators.region.deallocate != nullptr);
MemoryRegion *memory_region = &(block_region->memory);
error_code = allocators.region.deallocate(user_context, memory_region);
block_region->memory.handle = nullptr;
}
int error_code = deallocate_block_region_if_unused(user_context, block_region);
block_region->usage_count = 0;
block_region->status = AllocationStatus::Available;
return error_code;
}

int RegionAllocator::deallocate_block_region_if_unused(void *user_context, BlockRegion *region) {
if ((region->usage_count != 0) || (region->memory.handle == nullptr)) {
return 0;
}

#ifdef DEBUG_RUNTIME_INTERNAL
debug(user_context) << "RegionAllocator: deallocating unused region ("
<< "block_ptr=" << (void *)region->block_ptr << " "
<< "block_region=" << (void *)region << " "
<< "memory_size=" << (uint32_t)(region->memory.allocation.size) << " "
<< "block_reserved=" << (uint32_t)block->reserved << " "
<< ")";
#endif
halide_abort_if_false(user_context, allocators.region.deallocate != nullptr);
MemoryRegion *memory_region = &(region->memory);
int error_code = allocators.region.deallocate(user_context, memory_region);
region->memory.handle = nullptr;
return error_code;
}

int RegionAllocator::release(void *user_context) {
#ifdef DEBUG_RUNTIME_INTERNAL
debug(user_context) << "RegionAllocator: Releasing all regions ("
Expand Down
47 changes: 31 additions & 16 deletions test/runtime/block_allocator.cpp
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -43,8 +43,19 @@ int deallocate_block(void *user_context, MemoryBlock *block) {
return halide_error_code_success;
}

void *encode_region_handle(size_t size) {
return (void *)(size + 1);
}

void check_region(void *user_context, MemoryRegion *region) {
HALIDE_CHECK(user_context, region != nullptr);
HALIDE_CHECK(user_context, region->handle == encode_region_handle(region->allocation.size));
}

int allocate_region(void *user_context, MemoryRegion *region) {
region->handle = (void *)1;
HALIDE_CHECK(user_context, region->handle == nullptr);

region->handle = encode_region_handle(region->allocation.size);
allocated_region_memory += region->allocation.size;

debug(user_context) << "Test : allocate_region ("
Expand All @@ -57,7 +68,8 @@ int allocate_region(void *user_context, MemoryRegion *region) {
}

int deallocate_region(void *user_context, MemoryRegion *region) {
region->handle = (void *)0;
HALIDE_CHECK(user_context, region->handle == encode_region_handle(region->allocation.size));
region->handle = nullptr;
allocated_region_memory -= region->allocation.size;

debug(user_context) << "Test : deallocate_region ("
Expand Down Expand Up @@ -120,20 +132,20 @@ int main(int argc, char **argv) {
request.properties.usage = MemoryUsage::DefaultUsage;

MemoryRegion *r1 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r1 != nullptr);
check_region(user_context, r1);
HALIDE_CHECK(user_context, allocated_block_memory == block_size);
HALIDE_CHECK(user_context, allocated_region_memory == request.size);

MemoryRegion *r2 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r2 != nullptr);
check_region(user_context, r2);
HALIDE_CHECK(user_context, allocated_block_memory == block_size);
HALIDE_CHECK(user_context, allocated_region_memory == (2 * request.size));

instance->reclaim(user_context, r1);
HALIDE_CHECK(user_context, allocated_region_memory == (1 * request.size));

MemoryRegion *r3 = instance->reserve(user_context, request);
halide_abort_if_false(user_context, r3 != nullptr);
check_region(user_context, r3);
halide_abort_if_false(user_context, allocated_block_memory == block_size);
halide_abort_if_false(user_context, allocated_region_memory == (2 * request.size));
instance->retain(user_context, r3);
Expand All @@ -152,9 +164,9 @@ int main(int argc, char **argv) {

request.size = block_size / 2; // request two half-size regions
MemoryRegion *r4 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r4 != nullptr);
check_region(user_context, r4);
MemoryRegion *r5 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r5 != nullptr);
check_region(user_context, r5);
HALIDE_CHECK(user_context, nullptr == instance->reserve(user_context, request)); // requesting a third should fail

HALIDE_CHECK(user_context, allocated_block_memory == block_size);
Expand All @@ -167,7 +179,7 @@ int main(int argc, char **argv) {

request.size = block_size;
MemoryRegion *r6 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r6 != nullptr);
check_region(user_context, r6);

instance->destroy(user_context);
deallocate_block(user_context, memory_block);
Expand Down Expand Up @@ -308,12 +320,12 @@ int main(int argc, char **argv) {
request.properties.usage = MemoryUsage::DefaultUsage;

MemoryRegion *r1 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r1 != nullptr);
check_region(user_context, r1);
HALIDE_CHECK(user_context, allocated_block_memory == block_size);
HALIDE_CHECK(user_context, allocated_region_memory == padded_size);

MemoryRegion *r2 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r2 != nullptr);
check_region(user_context, r2);
HALIDE_CHECK(user_context, allocated_block_memory == block_size);
HALIDE_CHECK(user_context, allocated_region_memory == (2 * padded_size));

Expand All @@ -324,9 +336,9 @@ int main(int argc, char **argv) {

request.size = block_size / 2; // request two half-size regions
MemoryRegion *r4 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r4 != nullptr);
check_region(user_context, r4);
MemoryRegion *r5 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r5 != nullptr);
check_region(user_context, r5);
HALIDE_CHECK(user_context, nullptr == instance->reserve(user_context, request)); // requesting a third should fail

HALIDE_CHECK(user_context, allocated_block_memory == block_size);
Expand All @@ -339,7 +351,7 @@ int main(int argc, char **argv) {

request.size = block_size;
MemoryRegion *r6 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r6 != nullptr);
check_region(user_context, r6);

instance->destroy(user_context);
deallocate_block(user_context, memory_block);
Expand Down Expand Up @@ -380,20 +392,20 @@ int main(int argc, char **argv) {
request.properties.usage = MemoryUsage::DefaultUsage;

MemoryRegion *r1 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r1 != nullptr);
check_region(user_context, r1);
HALIDE_CHECK(user_context, allocated_block_memory == config.minimum_block_size);
HALIDE_CHECK(user_context, allocated_region_memory == request.size);

MemoryRegion *r2 = instance->reserve(user_context, request);
HALIDE_CHECK(user_context, r2 != nullptr);
check_region(user_context, r2);
HALIDE_CHECK(user_context, allocated_block_memory == config.minimum_block_size);
HALIDE_CHECK(user_context, allocated_region_memory == (2 * request.size));

instance->reclaim(user_context, r1);
HALIDE_CHECK(user_context, allocated_region_memory == (1 * request.size));

MemoryRegion *r3 = instance->reserve(user_context, request);
halide_abort_if_false(user_context, r3 != nullptr);
check_region(user_context, r3);
halide_abort_if_false(user_context, allocated_block_memory == config.minimum_block_size);
halide_abort_if_false(user_context, allocated_region_memory == (2 * request.size));
instance->retain(user_context, r3);
Expand Down Expand Up @@ -489,6 +501,7 @@ int main(int argc, char **argv) {
count = count > 1 ? count : 1;
request.size = count * sizeof(int);
MemoryRegion *region = instance->reserve(user_context, request);
check_region(user_context, region);
pointers.append(user_context, region);
}

Expand Down Expand Up @@ -533,6 +546,7 @@ int main(int argc, char **argv) {
request.size = count * sizeof(int);
total_allocation_size += request.size;
MemoryRegion *region = instance->reserve(user_context, request);
check_region(user_context, region);
pointers.append(user_context, region);
}

Expand All @@ -549,6 +563,7 @@ int main(int argc, char **argv) {
count = count > 1 ? count : 1;
request.size = count * sizeof(int);
MemoryRegion *region = instance->reserve(user_context, request);
check_region(user_context, region);
pointers.append(user_context, region);
}

Expand Down
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