diff options
| author | Karl Mehltretter <kmehltretter@gmail.com> | 2026-05-23 20:51:22 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-06-03 11:38:47 +0200 |
| commit | d8c897b20bf4d4cbb1e935a8ceb666bcc0f82580 (patch) | |
| tree | c21738200b49eb097fccc2103491e61d1ccaab50 /lib | |
| parent | cb19b8a9add2ed3774c1276e0a3906e52e8cf39a (diff) | |
| download | ath-d8c897b20bf4d4cbb1e935a8ceb666bcc0f82580.tar.gz | |
lockdep/selftests: Restore migrate_disable() state on PREEMPT_RT
The lockdep selftests deliberately run unbalanced locking patterns.
dotest() restores the task state they leave behind before running the
next testcase.
On PREEMPT_RT, spin_lock() uses migrate_disable() instead of disabling
preemption. dotest() cleans up the resulting migration-disabled state, but
that cleanup is still guarded by CONFIG_SMP.
That used to match the scheduler data model, where migration_disabled was
also CONFIG_SMP-only. The commit referenced below made SMP scheduler state
unconditional, so CONFIG_SMP=n PREEMPT_RT kernels with
CONFIG_DEBUG_LOCKING_API_SELFTESTS=y report success from the selftests and
then trip over stale current->migration_disabled state:
releasing a pinned lock
bad: scheduling from the idle thread!
Kernel panic - not syncing: Fatal exception
Save and restore current->migration_disabled for every PREEMPT_RT build.
Fixes: cac5cefbade9 ("sched/smp: Make SMP unconditional")
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/20260523185123.17482-2-kmehltretter@gmail.com
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/locking-selftest.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c index d939403331b5a..cb806b628352b 100644 --- a/lib/locking-selftest.c +++ b/lib/locking-selftest.c @@ -1431,9 +1431,7 @@ static void dotest(void (*testcase_fn)(void), int expected, int lockclass_mask) { int saved_preempt_count = preempt_count(); #ifdef CONFIG_PREEMPT_RT -#ifdef CONFIG_SMP int saved_mgd_count = current->migration_disabled; -#endif int saved_rcu_count = current->rcu_read_lock_nesting; #endif @@ -1471,10 +1469,8 @@ static void dotest(void (*testcase_fn)(void), int expected, int lockclass_mask) preempt_count_set(saved_preempt_count); #ifdef CONFIG_PREEMPT_RT -#ifdef CONFIG_SMP while (current->migration_disabled > saved_mgd_count) migrate_enable(); -#endif while (current->rcu_read_lock_nesting > saved_rcu_count) rcu_read_unlock(); |