From: Karl Mehltretter Date: Sat, 23 May 2026 18:51:23 +0000 (+0200) Subject: lockdep/selftests: Restore sched_rt_mutex state on PREEMPT_RT X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=06961d60a0e410bf8df69ccff7eb1bd824912b8f;p=thirdparty%2Flinux.git lockdep/selftests: Restore sched_rt_mutex state on PREEMPT_RT The WW-mutex selftests deliberately exercise failing lock paths. On PREEMPT_RT, some of those paths enter the RT-mutex scheduler helpers. The change referenced by the Fixes tag made those helpers track RT-mutex scheduling state in current->sched_rt_mutex. The bit is normally cleared by the matching post-schedule helper, but some WW-mutex selftests disable the runtime debug_locks flag before that happens. With debug_locks cleared, lockdep_assert() does not evaluate the expression that clears the bit, leaving stale state for the next testcase. With CONFIG_PREEMPT_RT=y and CONFIG_DEBUG_LOCKING_API_SELFTESTS=y, that stale state produces warnings such as: WARNING: kernel/sched/core.c:7557 at rt_mutex_pre_schedule+0x26/0x2d RIP: 0010:rt_mutex_pre_schedule+0x26/0x2d Save and restore current->sched_rt_mutex around each testcase, matching the existing PREEMPT_RT cleanup for task-local migration and RCU state. Fixes: d14f9e930b90 ("locking/rtmutex: Use rt_mutex specific scheduler helpers") Assisted-by: Codex:gpt-5 Signed-off-by: Karl Mehltretter Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260523185123.17482-3-kmehltretter@gmail.com --- diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c index cb806b628352b..bfafe1204c7b6 100644 --- a/lib/locking-selftest.c +++ b/lib/locking-selftest.c @@ -1433,6 +1433,7 @@ static void dotest(void (*testcase_fn)(void), int expected, int lockclass_mask) #ifdef CONFIG_PREEMPT_RT int saved_mgd_count = current->migration_disabled; int saved_rcu_count = current->rcu_read_lock_nesting; + int saved_sched_rt_mutex = current->sched_rt_mutex; #endif WARN_ON(irqs_disabled()); @@ -1469,6 +1470,8 @@ static void dotest(void (*testcase_fn)(void), int expected, int lockclass_mask) preempt_count_set(saved_preempt_count); #ifdef CONFIG_PREEMPT_RT + current->sched_rt_mutex = saved_sched_rt_mutex; + while (current->migration_disabled > saved_mgd_count) migrate_enable();