From d0a4e42ad03e29344b5182ca510fa14dc4e136d1 Mon Sep 17 00:00:00 2001
From: Sylvester Kaczmarek
 <16242628+sylvesterkaczmarek@users.noreply.github.com>
Date: Thu, 10 Sep 2026 10:42:36 +0100
Subject: [PATCH] Fix SVR zero-delta kernel cache state

Signed-off-by: Sylvester Kaczmarek <16242628+sylvesterkaczmarek@users.noreply.github.com>
---
 cpp/src/svm/kernelcache.cuh   |  4 +++-
 python/cuml/tests/test_svm.py | 11 +++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/cpp/src/svm/kernelcache.cuh b/cpp/src/svm/kernelcache.cuh
index 9883ca0f01..a50fda00d6 100644
--- a/cpp/src/svm/kernelcache.cuh
+++ b/cpp/src/svm/kernelcache.cuh
@@ -484,7 +484,9 @@ class KernelCache {
    */
   void InitWorkingSet(const int* ws_idx)
   {
-    ASSERT(cache_state != CacheState::WS_INITIALIZED, "Working set has already been initialized!");
+    // A block solve can produce no coefficient updates, in which case full-tile batching is
+    // skipped and the previous working set remains initialized. Replacing it is safe because
+    // no cache update is in progress.
     ASSERT(cache_state != CacheState::BATCHING_INITIALIZED, "Previous batching step incomplete!");
     this->ws_idx = ws_idx;
     if (svmType == EPSILON_SVR) {
diff --git a/python/cuml/tests/test_svm.py b/python/cuml/tests/test_svm.py
index e5b381c9da..ee13ecc1b2 100644
--- a/python/cuml/tests/test_svm.py
+++ b/python/cuml/tests/test_svm.py
@@ -445,6 +445,17 @@ def test_svr_skl_cmp(params, dataset, n_rows, n_cols):
     compare_svr(cuSVR, sklSVR, X_test, y_test)
 
 
+def test_svr_poly_zero_delta_working_set():
+    X = np.arange(5, dtype=np.float32).reshape(-1, 1)
+    y = np.arange(5, dtype=np.float32)
+
+    model = cu_svm.SVR(kernel="poly", degree=10).fit(X, y)
+    pred = np.asarray(model.predict(np.array([[2.0]], dtype=np.float32)))
+
+    assert pred.shape == (1,)
+    assert np.isfinite(pred).all()
+
+
 def test_svr_skl_cmp_weighted():
     """Compare to Sklearn SVR, use sample weights"""
     X, y = make_regression(