diff options
| author | Karl Mehltretter <kmehltretter@gmail.com> | 2026-05-23 20:51:23 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-06-03 11:38:47 +0200 |
| commit | 06961d60a0e410bf8df69ccff7eb1bd824912b8f (patch) | |
| tree | c47fa2fe7446298eef209a6baa2bd331509581cb /lib | |
| parent | d8c897b20bf4d4cbb1e935a8ceb666bcc0f82580 (diff) | |
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 <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
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/locking-selftest.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c index cb806b628352..bfafe1204c7b 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(); |