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: d14f9e930b ("locking/rtmutex: Use rt_mutex specific scheduler helpers")
Assisted-by: Codex:gpt-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20260523185123.17482-3-kmehltretter@gmail.com
Karl Mehltretter
06961d60a0