ggml-org/llama.cpp b11876

on GitHub

vulkan : one warp tile per subgroup in the small matmul tiles (#30106)

WM of the small tiles was 32, or 8 for 8-wide subgroups, whatever the
tile's BLOCK_SIZE and WARP. With 16-wide subgroups (Mali) the second
subgroup of a workgroup wrote into the next tile's columns. With 8-wide
subgroups some _id tiles left rows uncomputed. Derive WM so there is one
warp tile per subgroup.

Tested on my Pixel 9 Android phone. Before the change there were 20
MUL_MAT and 6 MUL_MAT_ID failures. After the change they all pass.

Fixes #28637

Assisted-by: Claude Opus 5.5