1704911 - "Buffer is not mapped" error when running Emscripten WebGPU cube example

Status: RESOLVED FIXED

(Core :: Graphics: WebGPU, defect)

Description

[Dzmitry Malyshau [:kvark]]

Code: https://hugoam.github.io/two/bgfx/01-cubes

Comment 1

[Dzmitry Malyshau [:kvark]]

Call stack:

wgpuBufferGetMappedRange(0, undefined) failed: InvalidStateError: GPUBuffer.getMappedRange: Buffer is not mapped 01-cubes:122:21
    printErr https://hugoam.github.io/two/bgfx/01-cubes:122
    _wgpuBufferGetMappedRange https://hugoam.github.io/two/bgfx/example-01-cubesDebug.js:6731
    wgpu::Buffer::GetMappedRange(unsigned long, unsigned long) const https://hugoam.github.io/two/bgfx/example-01-cubesDebug.wasm:1965872
    bgfx::webgpu::StagingBufferWgpu::map()::$_3::operator()(WGPUBufferMapAsyncStatus, void*) const https://hugoam.github.io/two/bgfx/example-01-cubesDebug.wasm:1380428
    bgfx::webgpu::StagingBufferWgpu::map()::$_3::__invoke(WGPUBufferMapAsyncStatus, void*) https://hugoam.github.io/two/bgfx/example-01-cubesDebug.wasm:1166973
    _wgpuBufferMapAsync

Comment 2

[Dzmitry Malyshau [:kvark]]

Internal assertion:

Assertion failure: mSegment (null segment), at /mnt/code/firefox/_webgpu/ipc/glue/Shmem.cpp:255
#01: mozilla::ipc::Shmem::RevokeRights(mozilla::ipc::Shmem::PrivateIPDLCaller) (/mnt/code/firefox/_webgpu/ipc/glue/Shmem.cpp:271)
#02: mozilla::ipc::IPDLParamTraits<mozilla::ipc::Shmem>::Write(IPC::Message*, mozilla::ipc::IProtocol*, mozilla::ipc::Shmem&&) (/mnt/code/firefox/_webgpu/ipc/glue/Shmem.cpp:444)
#03: mozilla::FunctionRef<void (IPC::Message*, mozilla::ipc::IProtocol*)>::FunctionRef<mozilla::webgpu::PWebGPUParent::OnMessageReceived(IPC::Message const&)::$_5::operator()(mozilla::ipc::Shmem&&) const::{lambda(IPC::Message*, mozilla::ipc::IProtocol*)#1}, int, (void*)0>()::{lambda(mozilla::FunctionRef<void (IPC::Message*, mozilla::ipc::IProtocol*)>::Payload const&, IPC::Message*, mozilla::ipc::IProtocol*)#1}::__invoke(mozilla::FunctionRef<void (IPC::Message*, mozilla::ipc::IProtocol*)>::Payload const&, IPC::Message*, mozilla::ipc::IProtocol*) (/mnt/code/firefox/_webgpu/obj-x86_64-pc-linux-gnu/dist/include/mozilla/FunctionRef.h:180)
#04: mozilla::ipc::IPDLResolverInner::ResolveOrReject(bool, mozilla::FunctionRef<void (IPC::Message*, mozilla::ipc::IProtocol*)>) (/mnt/code/firefox/_webgpu/ipc/glue/ProtocolUtils.cpp:947)
#05: std::_Function_handler<void (mozilla::ipc::Shmem&&), mozilla::webgpu::PWebGPUParent::OnMessageReceived(IPC::Message const&)::$_5>::_M_invoke(std::_Any_data const&, mozilla::ipc::Shmem&&) (/home/kvark/.mozbuild/clang/include/c++/7.4.0/bits/std_function.h:316)
#06: mozilla::webgpu::MapCallback(mozilla::webgpu::ffi::WGPUBufferMapAsyncStatus, unsigned char*) (/mnt/code/firefox/_webgpu/dom/webgpu/ipc/WebGPUParent.cpp:306)
#07: wgpu_core::device::fire_map_callbacks (/mnt/code/firefox/_webgpu/gfx/wgpu/wgpu-core/src/device/mod.rs:245)
#08: wgpu_core::device::queue::<impl wgpu_core::hub::Global<G>>::queue_submit (/mnt/code/firefox/_webgpu/gfx/wgpu/wgpu-core/src/device/queue.rs:832)
#09: wgpu_server_queue_submit (/mnt/code/firefox/_webgpu/gfx/wgpu_bindings/src/server.rs:580)
#10: mozilla::webgpu::WebGPUParent::RecvQueueSubmit(unsigned long, unsigned long, nsTArray<unsigned long> const&) (/mnt/code/firefox/_webgpu/dom/webgpu/ipc/WebGPUParent.cpp:396)
#11: mozilla::webgpu::PWebGPUParent::OnMessageReceived(IPC::Message const&) (/mnt/code/firefox/_webgpu/obj-x86_64-pc-linux-gnu/ipc/ipdl/PWebGPUParent.cpp:0)
#12: mozilla::layers::PCompositorManagerParent::OnMessageReceived(IPC::Message const&) (/mnt/code/firefox/_webgpu/obj-x86_64-pc-linux-gnu/ipc/ipdl/PCompositorManagerParent.cpp:200)
#13: mozilla::ipc::MessageChannel::DispatchAsyncMessage(mozilla::ipc::ActorLifecycleProxy*, IPC::Message const&) (/mnt/code/firefox/_webgpu/ipc/glue/MessageChannel.cpp:2155)
#14: mozilla::ipc::MessageChannel::DispatchMessage(IPC::Message&&) (/mnt/code/firefox/_webgpu/ipc/glue/MessageChannel.cpp:2081)
#15: mozilla::ipc::MessageChannel::RunMessage(mozilla::ipc::MessageChannel::MessageTask&) (/mnt/code/firefox/_webgpu/ipc/glue/MessageChannel.cpp:0)
#16: mozilla::ipc::MessageChannel::MessageTask::Run() (/mnt/code/firefox/_webgpu/ipc/glue/MessageChannel.cpp:1959)
#17: nsThread::ProcessNextEvent(bool, bool*) (/mnt/code/firefox/_webgpu/xpcom/threads/nsThread.cpp:1150)
#18: NS_ProcessNextEvent(nsIThread*, bool) (/mnt/code/firefox/_webgpu/xpcom/threads/nsThreadUtils.cpp:548)
#19: mozilla::ipc::MessagePumpForNonMainThreads::Run(base::MessagePump::Delegate*) (/mnt/code/firefox/_webgpu/ipc/glue/MessagePump.cpp:303)
#20: MessageLoop::RunInternal() (/mnt/code/firefox/_webgpu/ipc/chromium/src/base/message_loop.cc:0)
#21: MessageLoop::Run() (/mnt/code/firefox/_webgpu/ipc/chromium/src/base/message_loop.cc:311)
#22: nsThread::ThreadFunc(void*) (/mnt/code/firefox/_webgpu/xpcom/threads/nsThread.cpp:393)
#23: _pt_root (/mnt/code/firefox/_webgpu/nsprpub/pr/src/pthreads/ptthread.c:204)
#24: ??? (/usr/lib/libpthread.so.0 + 0x95c6)
#25: clone (/usr/lib/haswell/libc.so.6 + 0x11e4d3)
#26: ??? (???:???)

Comment 3

[Dzmitry Malyshau [:kvark]]

Looks like a race condition: inserting a bunch of printf calls hides the error and makes this case to actually work.

Comment 4

[Dzmitry Malyshau [:kvark]]

Nvm, the change that hid the error was that the server content behind the URL was changed, to work around this very issue.
I'm preparing a fix shortly.

Comment 5

[Dzmitry Malyshau [:kvark]]

Attachment: Fix Shmem circulation for buffers that are both mappable and mapped at creation

We are now passing an extra flag on Unmap to keep the shmem around.
Previously, we'd be freeing the Shmem accidentally on buffers that are writable and mapped at creation.
We also add a bit of logging on the WebGPUParent side.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4f124a8d83d1
Fix Shmem circulation for buffers that are both mappable and mapped at creation r=jgilbert

Comment 7

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/4f124a8d83d1