Bug 305401 – [GTK3] leaks DMA-BUF allocations when loading and unloading web pages

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKitGTK

[Gavin Stark]

Created attachment 477983 [details]
Sample app, including Makefile and sample content

The leak occurs during normal page navigation without any video or WebGL content. Memory usage grows continuously and buff
ers are never released.

Setting `WEBKIT_DISABLE_DMABUF_RENDERER=1` completely stops the leak, confirming the issue is in the DMABuf rendering path.

## Steps to Reproduce

1. Launch the included sample application
2. Monitor DMA-BUF allocations: `sudo cat /sys/kernel/debug/dma_buf/bufinfo` as well as `/proc/<PID>/fd`
3. Launch the test application: `./gtk_webkit_viewer file:///path/to/file/index.html 5 360 > log.txt`
4. Observe that DMA-BUF count increases and does not return to baseline
5. Observe data in `log.txt`

## Expected Behavior

DMA-BUF allocations should be released when pages are unloaded or navigated away from. Buffer count should return to baseline after navigation.

## Actual Behavior

DMA-BUF allocations accumulate with each page load/unload cycle. Buffers are never freed until the process is terminated.

## Observed

With the test code provided entries in `/proc/<PID>/fd` keep accumulating all pointing to dmabuf.

## Workaround

Setting `WEBKIT_DISABLE_DMABUF_RENDERER=1` prevents the leak by falling back to SHM-based rendering but impacts performance.

## System Information

- Distribution: Ubuntu 22.04 or 24.04
- Kernel: 5.15.0-164-generic
- WebKitGTK version: 2.44.0
- Mesa version: libegl-mesa0:amd64 23.2.1-1ubuntu3.1~22.04.3
- GPU:
	04:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Raven Ridge [Radeon Vega Series / Radeon Vega Mobile Series] (rev 85)
	04:00.7 Non-VGA unclassified device: Advanced Micro Devices, Inc. [AMD] Raven/Raven2/Renoir Non-Sensor Fusion Hub KMDF driver
- DRM driver:
	OpenGL renderer string: AMD Ryzen Embedded V1202B with Radeon Vega Gfx (raven, LLVM 15.0.7, DRM 3.42, 5.15.0-164-generic)

[Carlos Garcia Campos]

We keep the DMA-BUF buffers mapped in the UI process because we are failing to delete the associated texture. We need to make sure the gl context is current before calling glDeleteTextures()

[Carlos Garcia Campos]

Pull request: https://github.com/WebKit/WebKit/pull/56555

[EWS]

Committed 305700@main (6fab811984ab): <https://commits.webkit.org/305700@main>

Reviewed commits have been landed. Closing PR #56555 and removing active labels.