Messages in this thread Patch in this message | | | Date | Thu, 19 Aug 2021 20:17:53 +0200 | From | Peter Zijlstra <> | Subject | Re: [patch V5 41/72] locking/ww_mutex: Gather mutex_waiter initialization |
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On Thu, Aug 19, 2021 at 07:51:10PM +0200, Sebastian Andrzej Siewior wrote: > On 2021-08-15 23:28:39 [+0200], Thomas Gleixner wrote: > > --- a/kernel/locking/mutex-debug.c > > +++ b/kernel/locking/mutex-debug.c > > @@ -30,6 +30,7 @@ void debug_mutex_lock_common(struct mute > > memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter)); > > waiter->magic = waiter; > > INIT_LIST_HEAD(&waiter->list); > > + waiter->ww_ctx = MUTEX_POISON_WW_CTX; > > } > > > > void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter) > > --- a/kernel/locking/mutex.c > > +++ b/kernel/locking/mutex.c > > @@ -980,17 +980,15 @@ static __always_inline int __sched > > } > > > > debug_mutex_lock_common(lock, &waiter); > > + waiter.task = current; > > + if (ww_ctx) > > + waiter.ww_ctx = ww_ctx; > > > > lock_contended(&lock->dep_map, ip); > > > > if (!use_ww_ctx) { > > /* add waiting tasks to the end of the waitqueue (FIFO): */ > > __mutex_add_waiter(lock, &waiter, &lock->wait_list); > > - > > - > > -#ifdef CONFIG_DEBUG_MUTEXES > > - waiter.ww_ctx = MUTEX_POISON_WW_CTX; > > -#endif > > The crash, Guenter Roeck reported, is because now waiter.ww_ctx is > always initialized to poisen. > Previously in the ww-mutex case without a context it was set to NULL > in the next hunk. > Keeping the ww_ctx assigment in the next hunk seems to work.
You mean the 'use_ww_ctx && !ww_ctx' case?
Would not the below also help with that?
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 3a65bf4bacfd..d456579d0952 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -618,7 +618,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas debug_mutex_lock_common(lock, &waiter); waiter.task = current; - if (ww_ctx) + if (use_ww_ctx) waiter.ww_ctx = ww_ctx; lock_contended(&lock->dep_map, ip);
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