John Stultz 82f9cc0949 locking: rtmutex: Fix wake_q logic in task_blocks_on_rt_mutex ... Anders had bisected a crash using PREEMPT_RT with linux-next and isolated it down to commit 894d1b3db4 ("locking/mutex: Remove wakeups from under mutex::wait_lock"), where it seemed the wake_q structure was somehow getting corrupted causing a null pointer traversal. I was able to easily repoduce this with PREEMPT_RT and managed to isolate down that through various call stacks we were actually calling wake_up_q() twice on the same wake_q. I found that in the problematic commit, I had added the wake_up_q() call in task_blocks_on_rt_mutex() around __ww_mutex_add_waiter(), following a similar pattern in __mutex_lock_common(). However, its just wrong. We haven't dropped the lock->wait_lock, so its contrary to the point of the original patch. And it didn't match the __mutex_lock_common() logic of re-initializing the wake_q after calling it midway in the stack. Looking at it now, the wake_up_q() call is incorrect and should just be removed. So drop the erronious logic I had added. Fixes: 894d1b3db4 ("locking/mutex: Remove wakeups from under mutex::wait_lock") Closes: https://lore.kernel.org/lkml/6afb936f-17c7-43fa-90e0-b9e780866097@app.fastmail.com/ Reported-by: Anders Roxell <anders.roxell@linaro.org> Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: John Stultz <jstultz@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Juri Lelli <juri.lelli@redhat.com> Tested-by: Anders Roxell <anders.roxell@linaro.org> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20241114190051.552665-1-jstultz@google.com		2024-12-02 12:01:29 +01:00
..
irqflag-debug.c
lock_events.c
lock_events.h
lock_events_list.h
lockdep.c	lockdep: Use info level for lockdep initial info messages	2024-10-17 21:21:16 -07:00
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
locktorture.c
Makefile
mcs_spinlock.h
mutex-debug.c
mutex.c	locking/mutex: Expose __mutex_owner()	2024-10-14 12:52:41 +02:00
mutex.h	locking/mutex: Expose __mutex_owner()	2024-10-14 12:52:41 +02:00
osq_lock.c	locking/osq_lock: Use atomic_try_cmpxchg_release() in osq_unlock()	2024-10-25 10:01:50 +02:00
percpu-rwsem.c
qrwlock.c
qspinlock.c
qspinlock_paravirt.h	locking/pvqspinlock: Convert fields of 'enum vcpu_state' to uppercase	2024-10-17 21:21:16 -07:00
qspinlock_stat.h
rtmutex.c	locking: rtmutex: Fix wake_q logic in task_blocks_on_rt_mutex	2024-12-02 12:01:29 +01:00
rtmutex_api.c	Scheduler changes for v6.13:	2024-11-19 14:16:06 -08:00
rtmutex_common.h	locking/mutex: Remove wakeups from under mutex::wait_lock	2024-10-14 12:52:40 +02:00
rwbase_rt.c	locking/mutex: Remove wakeups from under mutex::wait_lock	2024-10-14 12:52:40 +02:00
rwsem.c	locking/mutex: Remove wakeups from under mutex::wait_lock	2024-10-14 12:52:40 +02:00
semaphore.c
spinlock.c
spinlock_debug.c
spinlock_rt.c	Scheduler changes for v6.13:	2024-11-19 14:16:06 -08:00
test-ww_mutex.c	locking/ww_mutex: Adjust to lockdep nest_lock requirements	2024-10-09 15:08:25 +02:00
ww_mutex.h	locking/mutex: Make mutex::wait_lock irq safe	2024-10-14 12:52:40 +02:00
ww_rt_mutex.c