KCSAN reports: BUG: KCSAN: data-race in do_raw_write_lock / do_raw_write_lock write (marked) to 0xffff800009cf504c of 4 bytes by task 1102 on cpu 1: do_raw_write_lock+0x120/0x204 _raw_write_lock_irq do_exit call_usermodehelper_exec_async ret_from_fork read to 0xffff800009cf504c of 4 bytes by task 1103 on cpu 0: do_raw_write_lock+0x88/0x204 _raw_write_lock_irq do_exit call_usermodehelper_exec_async ret_from_fork value changed: 0xffffffff -> 0x00000001 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 1103 Comm: kworker/u4:1 6.1.111 Commit 1a365e822372 ("locking/spinlock/debug: Fix various data races") has adressed most of these races, but seems to be not consistent/not complete. >From do_raw_write_lock() only debug_write_lock_after() part has been converted to WRITE_ONCE(), but not debug_write_lock_before() part. Do it now.
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| @@ -184,8 +184,8 @@ void do_raw_read_unlock(rwlock_t *lock) · 183 unmodified lines | |||
| 184 | static inline void debug_write_lock_before(rwlock_t *lock) | 184 | static inline void debug_write_lock_before(rwlock_t *lock) |
| 185 | { | 185 | { |
| 186 | RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); | 186 | RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); |
| 187 | RWLOCK_BUG_ON(lock->owner == current, lock, "recursion"); | 187 | RWLOCK_BUG_ON(READ_ONCE(lock->owner) == current, lock, "recursion"); |
| 188 | RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(), | 188 | RWLOCK_BUG_ON(READ_ONCE(lock->owner_cpu) == raw_smp_processor_id(), |
| 189 | lock, "cpu recursion"); | 189 | lock, "cpu recursion"); |
| 190 | } | 190 | } |
| 191 | 191 | ||