* kernel/time/timer_migration.c:1729 tmigr_setup_groups() error: we previously assumed 'start' could be null (see line 1630)
@ 2026-07-02 4:31 kernel test robot
0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2026-07-02 4:31 UTC (permalink / raw)
To: oe-kbuild; +Cc: lkp, Dan Carpenter
BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: linux-kernel@vger.kernel.org
TO: Frederic Weisbecker <frederic@kernel.org>
CC: Thomas Gleixner <tglx@linutronix.de>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 4a50a141f05a8d1737661b19ee22ff8455b94409
commit: 5eb579dfd46b4949117ecb0f1ba2f12d3dc9a6f2 timers/migration: Fix imbalanced NUMA trees
date: 8 months ago
:::::: branch date: 4 hours ago
:::::: commit date: 8 months ago
config: sparc64-randconfig-r072-20260702 (https://download.01.org/0day-ci/archive/20260702/202607021231.Op9h0tLk-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
smatch: v0.5.0-9185-gbcc58b9c
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: 5eb579dfd46b ("timers/migration: Fix imbalanced NUMA trees")
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202607021231.Op9h0tLk-lkp@intel.com/
smatch warnings:
kernel/time/timer_migration.c:1729 tmigr_setup_groups() error: we previously assumed 'start' could be null (see line 1630)
vim +/start +1729 kernel/time/timer_migration.c
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1618
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1619 static int tmigr_setup_groups(unsigned int cpu, unsigned int node,
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1620 struct tmigr_group *start, bool activate)
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1621 {
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1622 struct tmigr_group *group, *child, **stack;
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1623 int i, top = 0, err = 0, start_lvl = 0;
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1624 bool root_mismatch = false;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1625
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1626 stack = kcalloc(tmigr_hierarchy_levels, sizeof(*stack), GFP_KERNEL);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1627 if (!stack)
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1628 return -ENOMEM;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1629
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 @1630 if (start) {
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1631 stack[start->level] = start;
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1632 start_lvl = start->level + 1;
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1633 }
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1634
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1635 if (tmigr_root)
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1636 root_mismatch = tmigr_root->numa_node != node;
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1637
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1638 for (i = start_lvl; i < tmigr_hierarchy_levels; i++) {
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1639 group = tmigr_get_group(cpu, node, i);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1640 if (IS_ERR(group)) {
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1641 err = PTR_ERR(group);
6c181b5667eea3 Frederic Weisbecker 2025-10-24 1642 i--;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1643 break;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1644 }
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1645
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1646 top = i;
6c181b5667eea3 Frederic Weisbecker 2025-10-24 1647 stack[i] = group;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1648
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1649 /*
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1650 * When booting only less CPUs of a system than CPUs are
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1651 * available, not all calculated hierarchy levels are required,
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1652 * unless a node mismatch is detected.
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1653 *
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1654 * The loop is aborted as soon as the highest level, which might
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1655 * be different from tmigr_hierarchy_levels, contains only a
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1656 * single group, unless the nodes mismatch below tmigr_crossnode_level
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1657 */
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1658 if (group->parent)
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1659 break;
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1660 if ((!root_mismatch || i >= tmigr_crossnode_level) &&
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1661 list_is_singular(&tmigr_level_list[i]))
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1662 break;
6c181b5667eea3 Frederic Weisbecker 2025-10-24 1663 }
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1664
6c181b5667eea3 Frederic Weisbecker 2025-10-24 1665 /* Assert single root without parent */
6c181b5667eea3 Frederic Weisbecker 2025-10-24 1666 if (WARN_ON_ONCE(i >= tmigr_hierarchy_levels))
6c181b5667eea3 Frederic Weisbecker 2025-10-24 1667 return -EINVAL;
868c9037df626b Frederic Weisbecker 2025-02-05 1668
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1669 for (; i >= start_lvl; i--) {
6c181b5667eea3 Frederic Weisbecker 2025-10-24 1670 group = stack[i];
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1671
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1672 if (err < 0) {
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1673 list_del(&group->list);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1674 kfree(group);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1675 continue;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1676 }
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1677
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1678 WARN_ON_ONCE(i != group->level);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1679
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1680 /*
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1681 * Update tmc -> group / child -> group connection
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1682 */
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1683 if (i == 0) {
10a0e6f3d3db7d Anna-Maria Behnsen 2024-07-17 1684 struct tmigr_cpu *tmc = per_cpu_ptr(&tmigr_cpu, cpu);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1685
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1686 tmc->tmgroup = group;
835a9a67f54f01 Anna-Maria Behnsen 2024-07-16 1687 tmc->groupmask = BIT(group->num_children++);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1688
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1689 tmigr_init_root(group, activate);
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1690
36e40df35d2c18 Anna-Maria Behnsen 2024-02-22 1691 trace_tmigr_connect_cpu_parent(tmc);
36e40df35d2c18 Anna-Maria Behnsen 2024-02-22 1692
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1693 /* There are no children that need to be connected */
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1694 continue;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1695 } else {
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1696 child = stack[i - 1];
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1697 tmigr_connect_child_parent(child, group, activate);
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1698 }
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1699 }
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1700
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1701 if (err < 0)
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1702 goto out;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1703
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1704 if (activate) {
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1705 struct tmigr_walk data;
868c9037df626b Frederic Weisbecker 2025-02-05 1706
868c9037df626b Frederic Weisbecker 2025-02-05 1707 /*
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1708 * To prevent inconsistent states, active children need to be active in
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1709 * the new parent as well. Inactive children are already marked inactive
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1710 * in the parent group:
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1711 *
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1712 * * When new groups were created by tmigr_setup_groups() starting from
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1713 * the lowest level, then they are not active. They will be set active
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1714 * when the new online CPU comes active.
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1715 *
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1716 * * But if new groups above the current top level are required, it is
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1717 * mandatory to propagate the active state of the already existing
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1718 * child to the new parents. So tmigr_active_up() activates the
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1719 * new parents while walking up from the old root to the new.
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1720 *
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1721 * * It is ensured that @start is active, as this setup path is
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1722 * executed in hotplug prepare callback. This is executed by an
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1723 * already connected and !idle CPU. Even if all other CPUs go idle,
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1724 * the CPU executing the setup will be responsible up to current top
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1725 * level group. And the next time it goes inactive, it will release
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1726 * the new childmask and parent to subsequent walkers through this
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1727 * @child. Therefore propagate active state unconditionally.
10a0e6f3d3db7d Anna-Maria Behnsen 2024-07-17 1728 */
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 @1729 WARN_ON_ONCE(!start->parent);
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1730 data.childmask = start->groupmask;
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1731 __walk_groups_from(tmigr_active_up, &data, start, start->parent);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1732 }
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1733
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1734 /* Root update */
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1735 if (list_is_singular(&tmigr_level_list[top])) {
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1736 group = list_first_entry(&tmigr_level_list[top],
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1737 typeof(*group), list);
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1738 WARN_ON_ONCE(group->parent);
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1739 if (tmigr_root) {
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1740 /* Old root should be the same or below */
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1741 WARN_ON_ONCE(tmigr_root->level > top);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1742 }
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1743 tmigr_root = group;
d7ad05c86e2191 Levi Yun 2024-05-06 1744 }
5eb579dfd46b49 Frederic Weisbecker 2025-10-24 1745 out:
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1746 kfree(stack);
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1747
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1748 return err;
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1749 }
7ee988770326fc Anna-Maria Behnsen 2024-02-22 1750
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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2026-07-02 4:31 kernel/time/timer_migration.c:1729 tmigr_setup_groups() error: we previously assumed 'start' could be null (see line 1630) kernel test robot
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