From: Jeff Bolz <redacted>
Date: Tue, 24 Feb 2026 06:43:12 +0000 (-0600)
Subject: vulkan: fix data race in mul_mat_id shader (llama/19790)
X-Git-Tag: v0.9.8~111
X-Git-Url: https://git.djapps.eu/?a=commitdiff_plain;h=037fdb12bd1283d48fcb855581518a7b256f7f99;p=pkg%2Fggml%2Fsources%2Fggml

vulkan: fix data race in mul_mat_id shader (llama/19790)
---

diff --git a/src/ggml-vulkan/vulkan-shaders/mul_mm_cm2.comp b/src/ggml-vulkan/vulkan-shaders/mul_mm_cm2.comp
index 717d124e..497a18ff 100644
--- a/src/ggml-vulkan/vulkan-shaders/mul_mm_cm2.comp
+++ b/src/ggml-vulkan/vulkan-shaders/mul_mm_cm2.comp
@@ -167,7 +167,9 @@ void load_row_ids(uint expert_idx, bool nei0_is_pow2, uint ic) {
         uint id = ids[iter++];
         uvec4 ballot = subgroupBallot(in_range && id == expert_idx);
 
-        ballots_sh[gl_SubgroupID] = ballot;
+        if (gl_SubgroupInvocationID == 0) {
+            ballots_sh[gl_SubgroupID] = ballot;
+        }
         barrier();
 
         uint subgroup_base = 0;
diff --git a/src/ggml-vulkan/vulkan-shaders/mul_mm_id_funcs.glsl b/src/ggml-vulkan/vulkan-shaders/mul_mm_id_funcs.glsl
index 743004ff..26c5c12a 100644
--- a/src/ggml-vulkan/vulkan-shaders/mul_mm_id_funcs.glsl
+++ b/src/ggml-vulkan/vulkan-shaders/mul_mm_id_funcs.glsl
@@ -43,7 +43,9 @@ void load_row_ids(uint expert_idx, bool nei0_is_pow2, uint ic) {
         uint id = ids[iter++];
         uvec4 ballot = subgroupBallot(in_range && id == expert_idx);
 
-        ballots_sh[gl_SubgroupID] = ballot;
+        if (gl_SubgroupInvocationID == 0) {
+            ballots_sh[gl_SubgroupID] = ballot;
+        }
         barrier();
 
         uint subgroup_base = 0;