segfault on arm64/freedreno in vk_malloc_import: vk->GetMemoryHostPointerPropertiesEXT is NULL

[Infinoid]

[Note: I've applied for an account at code.videolan.org, it's waiting for approval. Posting here in the meantime.]

I'm running mpv on arm64, and it segfaults whenever I try to take a screenshot.

Backtrace:

(lldb) bt
* thread #1, name = 'mpv', stop reason = signal SIGSEGV: address not mapped to object
    frame #0: 0x0000000000000000
  * frame #1: 0x0000e51fbfc92c20 libplacebo.so.351`vk_malloc_import(ma=0x0000e51f7c075a10, out=0x0000e51f7c38b868, params=0x0000e51faa1ed3e0) at malloc.c:870:9
    frame #2: 0x0000e51fbfc8b5e8 libplacebo.so.351`vk_buf_create at gpu_buf.c:224:10
    frame #3: 0x0000e51fbfc5e990 libplacebo.so.351`pl_buf_create at gpu.c:607:18
    frame #4: 0x0000e51fbfc61700 libplacebo.so.351`pl_tex_download_pbo at utils.c:629:15
    frame #5: 0x0000e51fbfc8d77c libplacebo.so.351`vk_tex_download at gpu_tex.c:1002:16
    frame #6: 0x0000e51fbfc5e7ac libplacebo.so.351`pl_tex_download at gpu.c:527:12
    frame #7: 0x0000c206fd7df950 mpv`tex_download_pl at ra_pl.c:238:12
    frame #8: 0x0000c206fd7cef68 mpv`gl_video_screenshot at video.c:3624:10
    frame #9: 0x0000c206fd7d5e30 mpv`control at vo_gpu.c:199:13
    frame #10: 0x0000c206fd7d2d24 mpv`run_control at vo.c:658:15
    frame #11: 0x0000c206fd751458 mpv`mp_dispatch_queue_process at dispatch.c:300:13
    frame #12: 0x0000c206fd7d4b18 mpv`vo_thread at vo.c:1141:9
    frame #13: 0x0000e51fbe535f78 libc.so.6`___lldb_unnamed_symbol3490 + 920
    frame #14: 0x0000e51fbe59de8c libc.so.6`___lldb_unnamed_symbol3864 + 12

Direct cause: this code tries to call through a null pointer.

(lldb) p vk->GetMemoryHostPointerPropertiesEXT
(PFN_vkGetMemoryHostPointerPropertiesEXT) 0x0000000000000000

I've posted the other fields of the vk structure to this gist.

Software versions:

• debian forky (testing)
• mpv 0.40.0-5+b1
• libplacebo 7.351.0-2
• mesa-vulkan-drivers v25.2.6-1
• libvulkan1 1.4.328.1-1
• libdrm-freedreno1 2.4.127-1

Hardware:

• Lenovo ThinkPad T14s Qualcomm Gen 6, product page
• vulkaninfo gist
• glxinfo gist

I'm not sure this is a libplacebo bug, or if libplacebo just happens to be the site of the crash. It looks (from vulkaninfo) like the vulkan provider (mesa/freedreno) advertises the VK_EXT_external_memory_host extension, but (from printing the vk struct contents) doesn't implement GetMemoryHostPointerPropertiesEXT. Is this a situation where libplacebo should look before it leaps, is this a mesa/freedreno bug, or both?

[Update] No, it's llvmpipe that advertises that extension, not freedreno. (I'm learning how to read vulkaninfo output.)

[Infinoid]

I posted this possible fix over on gitlab.