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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Mike Galbraith <efault@gmx.de>,
	Guenter Roeck <linux@roeck-us.net>
Subject: Re: [patch V5 41/72] locking/ww_mutex: Gather mutex_waiter initialization
Date: Thu, 19 Aug 2021 19:51:10 +0200	[thread overview]
Message-ID: <20210819175110.w7lxq5w3gdj5vhwf@linutronix.de> (raw)
In-Reply-To: <20210815211304.281927514@linutronix.de>

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.

>  	} else {
>  		/*
>  		 * Add in stamp order, waking up waiters that must kill
> @@ -999,12 +997,8 @@ static __always_inline int __sched
>  		ret = __ww_mutex_add_waiter(&waiter, lock, ww_ctx);
>  		if (ret)
>  			goto err_early_kill;
> -
> -		waiter.ww_ctx = ww_ctx;
>  	}
>  
> -	waiter.task = current;
> -
>  	set_current_state(state);
>  	for (;;) {
>  		/*

Sebastian

  parent reply	other threads:[~2021-08-19 17:51 UTC|newest]

Thread overview: 160+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-15 21:27 [patch V5 00/72] locking, sched: The PREEMPT-RT locking infrastructure Thomas Gleixner
2021-08-15 21:27 ` [patch V5 01/72] locking/local_lock: Add missing owner initialization Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 02/72] locking/rtmutex: Set proper wait context for lockdep Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 03/72] sched: Split out the wakeup state check Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] sched/wakeup: Split out the wakeup ->__state check tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 04/72] sched: Introduce TASK_RTLOCK_WAIT Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] sched/wakeup: Introduce the TASK_RTLOCK_WAIT state bit tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 05/72] sched: Reorganize current::__state helpers Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] sched/wakeup: Reorganize the " tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 06/72] sched: Prepare for RT sleeping spin/rwlocks Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] sched/wakeup: " tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 07/72] sched: Rework the __schedule() preempt argument Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] sched/core: " tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 08/72] sched: Provide schedule point for RT locks Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] sched/core: Provide a scheduling " tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 09/72] sched/wake_q: Provide WAKE_Q_HEAD_INITIALIZER Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] sched/wake_q: Provide WAKE_Q_HEAD_INITIALIZER() tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 10/72] media/atomisp: Use lockdep instead of *mutex_is_locked() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2021-08-15 21:27 ` [patch V5 11/72] rtmutex: Remove rt_mutex_is_locked() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/rtmutex: " tip-bot2 for Peter Zijlstra
2021-08-15 21:27 ` [patch V5 12/72] rtmutex: Convert macros to inlines Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/rtmutex: " tip-bot2 for Sebastian Andrzej Siewior
2021-08-15 21:27 ` [patch V5 13/72] rtmutex: Switch to try_cmpxchg() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/rtmutex: Switch to from cmpxchg_*() to try_cmpxchg_*() tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 14/72] rtmutex: Split API and implementation Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/rtmutex: Split API from implementation tip-bot2 for Thomas Gleixner
2021-08-15 21:27 ` [patch V5 15/72] rtmutex: Split out the inner parts of struct rtmutex Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/rtmutex: Split out the inner parts of 'struct rtmutex' tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 16/72] locking/rtmutex: Provide rt_mutex_slowlock_locked() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 17/72] rtmutex: Provide rt_mutex_base_is_locked() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/rtmutex: " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 18/72] locking: Add base code for RT rw_semaphore and rwlock Thomas Gleixner
2021-08-16  5:00   ` Davidlohr Bueso
2021-08-17 20:14   ` [tip: locking/core] locking/rt: " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 19/72] locking/rwsem: Add rtmutex based R/W semaphore implementation Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 20/72] locking/rtmutex: Add wake_state to rt_mutex_waiter Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 21/72] locking/rtmutex: Provide rt_wake_q and helpers Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/rtmutex: Provide rt_wake_q_head " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 22/72] locking/rtmutex: Use rt_mutex_wake_q_head Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 23/72] locking/rtmutex: Prepare RT rt_mutex_wake_q for RT locks Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 24/72] locking/rtmutex: Guard regular sleeping locks specific functions Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 25/72] locking/spinlock: Split the lock types header Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/spinlock: Split the lock types header, and move the raw types into <linux/spinlock_types_raw.h> tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 26/72] locking/rtmutex: Prevent future include recursion hell Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2021-08-15 21:28 ` [patch V5 27/72] locking/lockdep: Reduce includes in debug_locks.h Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/lockdep: Reduce header dependencies in <linux/debug_locks.h> tip-bot2 for Sebastian Andrzej Siewior
2021-08-15 21:28 ` [patch V5 28/72] rbtree: Split out the rbtree type definitions Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] rbtree: Split out the rbtree type definitions into <linux/rbtree_types.h> tip-bot2 for Sebastian Andrzej Siewior
2021-08-15 21:28 ` [patch V5 29/72] locking/rtmutex: Include only rbtree types Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/rtmutex: Reduce <linux/rtmutex.h> header dependencies, only include <linux/rbtree_types.h> tip-bot2 for Sebastian Andrzej Siewior
2021-08-15 21:28 ` [patch V5 30/72] locking/spinlock: Provide RT specific spinlock type Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/spinlock: Provide RT specific spinlock_t tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 31/72] locking/spinlock: Provide RT variant header Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/spinlock: Provide RT variant header: <linux/spinlock_rt.h> tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 32/72] locking/rtmutex: Provide the spin/rwlock core lock function Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-27 17:21   ` [patch V5 32/72] " Boqun Feng
2021-08-27 20:03     ` Thomas Gleixner
2021-08-15 21:28 ` [patch V5 33/72] locking/spinlock: Provide RT variant Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 34/72] locking/rwlock: " Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-09-11  2:59   ` [patch V5 34/72] " Xiaoming Ni
2021-09-13  6:28     ` Sebastian Andrzej Siewior
2021-08-15 21:28 ` [patch V5 35/72] locking/rtmutex: Squash !RT tasks to DEFAULT_PRIO Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 36/72] locking/mutex: Consolidate core headers Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/mutex: Consolidate core headers, remove kernel/locking/mutex-debug.h tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 37/72] locking/mutex: Move waiter to core header Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/mutex: Move the 'struct mutex_waiter' definition from <linux/mutex.h> to the internal header tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 38/72] locking/ww_mutex: Move ww_mutex declarations into ww_mutex.h Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Move the ww_mutex definitions from <linux/mutex.h> into <linux/ww_mutex.h> tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 39/72] locking/mutex: Make mutex::wait_lock raw Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 40/72] locking/ww_mutex: Simplify lockdep annotation Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Simplify lockdep annotations tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 41/72] locking/ww_mutex: Gather mutex_waiter initialization Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2021-08-19 16:54   ` [patch V5 41/72] " Guenter Roeck
2021-08-19 18:08     ` [PATCH] locking/ww_mutex: Initialize waiter.ww_ctx properly Sebastian Andrzej Siewior
2021-08-19 18:22       ` Peter Zijlstra
2021-08-19 18:32         ` Sebastian Andrzej Siewior
2021-08-19 17:51   ` Sebastian Andrzej Siewior [this message]
2021-08-19 18:17     ` [patch V5 41/72] locking/ww_mutex: Gather mutex_waiter initialization Peter Zijlstra
2021-08-19 18:28       ` Sebastian Andrzej Siewior
2021-08-19 19:30       ` [PATCH v2] locking/ww_mutex: Initialize waiter.ww_ctx properly Sebastian Andrzej Siewior
2021-08-20 10:20         ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2021-08-15 21:28 ` [patch V5 42/72] locking/ww_mutex: Split up ww_mutex_unlock() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra (Intel)
2021-08-15 21:28 ` [patch V5 43/72] locking/ww_mutex: Split W/W implementation logic Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Split out the W/W implementation logic into kernel/locking/ww_mutex.h tip-bot2 for Peter Zijlstra (Intel)
2021-08-15 21:28 ` [patch V5 44/72] locking/ww_mutex: Remove __sched annotation Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Remove the __sched annotation from ww_mutex APIs tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 45/72] locking/ww_mutex: Abstract waiter iteration Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Abstract out the " tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 46/72] locking/ww_mutex: Abstract waiter enqueueing Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Abstract out " tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 47/72] locking/ww_mutex: Abstract mutex accessors Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Abstract out " tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 48/72] locking/ww_mutex: Abstract mutex types Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Abstract out " tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 49/72] locking/ww_mutex: Abstract internal lock access Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] locking/ww_mutex: Abstract out internal lock accesses tip-bot2 for Thomas Gleixner
2021-08-15 21:28 ` [patch V5 50/72] locking/ww_mutex: Implement rt_mutex accessors Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 51/72] locking/ww_mutex: Add RT priority to W/W order Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 52/72] locking/ww_mutex: Add rt_mutex based lock type and accessors Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2021-08-15 21:28 ` [patch V5 53/72] locking/rtmutex: Extend the rtmutex core to support ww_mutex Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2021-08-15 21:29 ` [patch V5 54/72] locking/ww_mutex: Implement rtmutex based ww_mutex API functions Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2021-08-15 21:29 ` [patch V5 55/72] locking/rtmutex: Add mutex variant for RT Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 56/72] lib/test_lockup: Adapt to changed variables Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2021-08-15 21:29 ` [patch V5 57/72] futex: Validate waiter correctly in futex_proxy_trylock_atomic() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 58/72] futex: Cleanup stale comments Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] futex: Clean up " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 59/72] futex: Clarify futex_requeue() PI handling Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 60/72] futex: Remove bogus condition for requeue PI Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 61/72] futex: Correct the number of requeued waiters for PI Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 62/72] futex: Restructure futex_requeue() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 63/72] futex: Clarify comment in futex_requeue() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 64/72] futex: Reorder sanity checks " Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 65/72] futex: Simplify handle_early_requeue_pi_wakeup() Thomas Gleixner
2021-08-17 20:14   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 66/72] futex: Prevent requeue_pi() lock nesting issue on RT Thomas Gleixner
2021-08-17 20:13   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 67/72] rtmutex: Prevent lockdep false positive with PI futexes Thomas Gleixner
2021-08-17 20:13   ` [tip: locking/core] locking/rtmutex: " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 68/72] preempt: Adjust PREEMPT_LOCK_OFFSET for RT Thomas Gleixner
2021-08-17 20:13   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 69/72] locking/rtmutex: Implement equal priority lock stealing Thomas Gleixner
2021-08-17 20:13   ` [tip: locking/core] " tip-bot2 for Gregory Haskins
2021-08-15 21:29 ` [patch V5 70/72] locking/rtmutex: Add adaptive spinwait mechanism Thomas Gleixner
2021-08-17 20:13   ` [tip: locking/core] " tip-bot2 for Steven Rostedt
2021-08-15 21:29 ` [patch V5 71/72] locking/spinlock/rt: Prepare for RT local_lock Thomas Gleixner
2021-08-17 20:13   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-15 21:29 ` [patch V5 72/72] locking/local_lock: Add PREEMPT_RT support Thomas Gleixner
2021-08-17 20:13   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2021-08-16  9:21 ` [patch V5 00/72] locking, sched: The PREEMPT-RT locking infrastructure Sebastian Andrzej Siewior

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