Thread safety question regarding concurrent access to VmaAllocator #525
Description
Hello, I am on the master and I create vmaAllocator with only flag VMA_ALLOCATOR_CREATE_BUFFER_DEVICE_ADDRESS_BIT. Based on the documentation:
all calls to functions that take #VmaAllocator as first parameter are safe to call from multiple threads simultaneously because they aresynchronized internally when needed.
However I got quite a bit warning from thread sanitizer warning about data race. I don't know if this is false positive or not but I think I should report.
Here is the trace from thread sanitizer.
WARNING: ThreadSanitizer: data race (pid=79053)
Write of size 8 at 0x00010b71fd30 by thread T36 (mutexes: write M0, write M1):
#0 VmaDeviceMemoryBlock::Unmap(VmaAllocator_T*, unsigned int) vk_mem_alloc.h:10824 (libframework.dylib:arm64+0x220d90)
#1 VmaAllocator_T::Unmap(VmaAllocation_T*) vk_mem_alloc.h:14645 (libframework.dylib:arm64+0x23895c)
#2 vmaUnmapMemory vk_mem_alloc.h:15998 (libframework.dylib:arm64+0x23e0f4)
#3 sp::vkm<vk::Buffer>::unmap_memory() vkm.cpp:396 (libframework.dylib:arm64+0x262fa8)
#4 void sp::vkm<vk::Buffer>::map<int>(std::__1::function<void (int*)>, unsigned long) vkm.hh:137 (libextras.dylib:arm64+0xe2834)
#5 sp::triangle_indices_manager::upload_all_entities()::$_0::operator()(vk::CommandBuffer, bool, sp::triangle_indices_manager::upload_all_entities()::ctx_t&) const triangle_indices.cc:292 (libextras.dylib:arm64+0xf58d8)
...
Previous read of size 8 at 0x00010b71fd30 by thread T38:
#0 VmaDeviceMemoryBlock::GetMappedData() const vk_mem_alloc.h:6314 (libframework.dylib:arm64+0x2232b0)
#1 VmaBlockVector::AllocatePage(unsigned long long, unsigned long long, VmaAllocationCreateInfo const&, VmaSuballocationType, VmaAllocation_T**) vk_mem_alloc.h:11484 (libframework.dylib:arm64+0x2255e4)
#2 VmaBlockVector::Allocate(unsigned long long, unsigned long long, VmaAllocationCreateInfo const&, VmaSuballocationType, unsigned long, VmaAllocation_T**) vk_mem_alloc.h:11381 (libframework.dylib:arm64+0x224f7c)
#3 VmaAllocator_T::AllocateMemoryOfType(VmaPool_T*, unsigned long long, unsigned long long, bool, VkBuffer_T*, VkImage_T*, VmaBufferImageUsage, VmaAllocationCreateInfo const&, unsigned int, VmaSuballocationType, VmaDedicatedAllocationList&, VmaBlockVector&, unsigned long, VmaAllocation_T**) vk_mem_alloc.h:13592 (libframework.dylib:arm64+0x233ba8)
#4 VmaAllocator_T::AllocateMemory(VkMemoryRequirements const&, bool, bool, VkBuffer_T*, VkImage_T*, VmaBufferImageUsage, VmaAllocationCreateInfo const&, VmaSuballocationType, unsigned long, VmaAllocation_T**) vk_mem_alloc.h:14111 (libframework.dylib:arm64+0x2366b4)
#5 vmaCreateBuffer vk_mem_alloc.h:16302 (libframework.dylib:arm64+0x23f594)
#6 sp::create_staging_buffer misc.cpp:243 (libframework.dylib:arm64+0xf36d8)
#7 data_provider::on_batch_resolve const data.cc:222 (visibility_batch:arm64+0x100096d94)
...
Location is heap block of size 296 at 0x00010b71fcc0 allocated by thread T34:
#0 posix_memalign <null> (libclang_rt.tsan_osx_dynamic.dylib:arm64e+0x60988)
#1 vma_aligned_alloc(unsigned long, unsigned long) vk_mem_alloc.h:3061 (libframework.dylib:arm64+0x264c58)
#2 VmaMalloc(VkAllocationCallbacks const*, unsigned long, unsigned long) vk_mem_alloc.h:4171 (libframework.dylib:arm64+0x264b60)
#3 VmaMalloc(VmaAllocator_T*, unsigned long, unsigned long) vk_mem_alloc.h:10614 (libframework.dylib:arm64+0x26e344)
#4 VmaDeviceMemoryBlock* VmaAllocate<VmaDeviceMemoryBlock>(VmaAllocator_T*) vk_mem_alloc.h:10625 (libframework.dylib:arm64+0x228244)
#5 VmaBlockVector::CreateBlock(unsigned long long, unsigned long*) vk_mem_alloc.h:11864 (libframework.dylib:arm64+0x22474c)
#6 VmaBlockVector::AllocatePage(unsigned long long, unsigned long long, VmaAllocationCreateInfo const&, VmaSuballocationType, VmaAllocation_T**) vk_mem_alloc.h:11564 (libframework.dylib:arm64+0x225a90)
#7 VmaBlockVector::Allocate(unsigned long long, unsigned long long, VmaAllocationCreateInfo const&, VmaSuballocationType, unsigned long, VmaAllocation_T**) vk_mem_alloc.h:11381 (libframework.dylib:arm64+0x224f7c)
#8 VmaAllocator_T::AllocateMemoryOfType(VmaPool_T*, unsigned long long, unsigned long long, bool, VkBuffer_T*, VkImage_T*, VmaBufferImageUsage, VmaAllocationCreateInfo const&, unsigned int, VmaSuballocationType, VmaDedicatedAllocationList&, VmaBlockVector&, unsigned long, VmaAllocation_T**) vk_mem_alloc.h:13592 (libframework.dylib:arm64+0x233ba8)
#9 VmaAllocator_T::AllocateMemory(VkMemoryRequirements const&, bool, bool, VkBuffer_T*, VkImage_T*, VmaBufferImageUsage, VmaAllocationCreateInfo const&, VmaSuballocationType, unsigned long, VmaAllocation_T**) vk_mem_alloc.h:14111 (libframework.dylib:arm64+0x2366b4)
#10 vmaCreateBuffer vk_mem_alloc.h:16302 (libframework.dylib:arm64+0x23f594)
#11 sp::create_staging_buffe misc.cpp:243 (libframework.dylib:arm64+0xf36d8)
#12 sp::instance_manager::upload_all_entities const instances.cc:270 (libextras.dylib:arm64+0xae538)
...
BTW, the create_staging_buffer() function is like this:
vkm<vk::Buffer>
create_staging_buffer(device_data& dev,
size_t size,
const void* data,
const std::string& name)
{
vk::Buffer res;
VmaAllocation alloc;
vk::BufferCreateInfo staging_info({},
size,
vk::BufferUsageFlagBits::eTransferSrc,
vk::SharingMode::eExclusive);
VmaAllocationCreateInfo alloc_info = {};
alloc_info.usage = VMA_MEMORY_USAGE_AUTO;
alloc_info.flags = VMA_ALLOCATION_CREATE_HOST_ACCESS_SEQUENTIAL_WRITE_BIT;
vmaCreateBuffer(dev.allocator,
(VkBufferCreateInfo*)&staging_info,
&alloc_info,
reinterpret_cast<VkBuffer*>(&res),
&alloc,
nullptr);
if (data)
{
void* mem = nullptr;
vmaMapMemory(dev.allocator, alloc, &mem);
memcpy(mem, data, size);
vmaUnmapMemory(dev.allocator, alloc);
}
return vkm<vk::Buffer>(dev, res, alloc, name);
}