From e7e439bd1dbc9fa5fea983358f7581c588045b73 Mon Sep 17 00:00:00 2001
From: Ilya Egorov <0x42005e1f@gmail.com>
Date: Fri, 2 Oct 2026 15:53:41 +0400
Subject: [PATCH 1/3] gh-158592: Reallocate the list's array when deleting by
 index

---
 Objects/listobject.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 81eb3e1102159b5..3f0c51904dec2dd 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -1148,7 +1148,7 @@ list_ass_item_lock_held(PyListObject *a, Py_ssize_t i, PyObject *v)
         for (Py_ssize_t idx = i; idx < size - 1; idx++) {
             FT_ATOMIC_STORE_PTR_RELEASE(a->ob_item[idx], a->ob_item[idx + 1]);
         }
-        Py_SET_SIZE(a, size - 1);
+        list_resize(a, size - 1);  // NB: shrinking a list can't fail
     }
     else {
         FT_ATOMIC_STORE_PTR_RELEASE(a->ob_item[i], Py_NewRef(v));

From 093ab9bacf1353b79d7d8a00e6850aaccbb3a2b5 Mon Sep 17 00:00:00 2001
From: Ilya Egorov <0x42005e1f@gmail.com>
Date: Fri, 2 Oct 2026 16:20:39 +0400
Subject: [PATCH 2/3] Add a NEWS entry

---
 .../2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst             | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst
new file mode 100644
index 000000000000000..150e7d4e70c5f68
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst
@@ -0,0 +1,3 @@
+Fix deletion by index from a :class:`list` (``del list[index]``), which did
+not reallocate the underlying array and thus did not free memory (a
+regression made in 3.13.0a5).

From 6f68a64cd7d055a84f407c643bd2c9f74fdb79bc Mon Sep 17 00:00:00 2001
From: Ilya Egorov <0x42005e1f@gmail.com>
Date: Sat, 3 Oct 2026 19:57:28 +0400
Subject: [PATCH 3/3] Apply the suggested change
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
---
 .../2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst           | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst
index 150e7d4e70c5f68..a2c8cdd2233c31d 100644
--- a/Misc/NEWS.d/next/Core_and_Builtins/2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-02-16-19-35.gh-issue-158592.V6W21J.rst
@@ -1,3 +1,2 @@
-Fix deletion by index from a :class:`list` (``del list[index]``), which did
-not reallocate the underlying array and thus did not free memory (a
-regression made in 3.13.0a5).
+Avoid holding memory much longer than needed after deleting
+an item from a list via :keyword:`del`.