Fix 1: s_k must equal actual n. With s_k < n, v_fmha layout only spans
first s_k V tokens and TMA reads OOB on later tiles.
Fix 2: TMA producer indexes K and V by kt (loop variable), NOT by the
pipeline's interleaved count. The kv pipeline interleaves K and V, so
pipeline count goes 0,1,2,3 but GMEM tiles should be K[0],V[0],K[1],V[1].
Fix 3: Online O rescale before softmax_done_bar. When row_max grows,
O must be multiplied by exp2(old_max - new_max) before MMA starts next PV.
biondizzle
1f489c3cc2