Dear RT folks! I'm pleased to announce the v5.2.19-rt11 patch set. Changes since v5.2.19-rt10: - Larger futex rework. Making the futex_hash_bucket lock a raw_spinlock_t in v5.0.21-rt14 fixed a one problem but led to other. This change has been reverted and the original problem was solved differently by Peter Zijlstra. - The upstream printk received a patch to not lose the last line in the kmsg buffer. John Ogness made a similar change to the printk code in -RT. - An optimisation by Waiman Long to avoid a memcmp() in the debug version of smp_processor_id() and this_cpu_.*() - The UBSAN report will be serialized using a spinlock_t which causes "sleeping while atomic" warnings if used from atomic context. Patch by Julien Grall. - Another fix to kmemleak to avoid acquiring a spinlock_t within an atomic region. Patch by Yongxin Liu and Liu Haitao. Known issues - None The delta patch against v5.2.19-rt10 is appended below and can be found here: https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.2/incr/patch-5.2.19-rt10-rt11.patch.xz You can get this release via the git tree at: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.2.19-rt11 The RT patch against v5.2.19 can be found here: https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patch-5.2.19-rt11.patch.xz The split quilt queue is available at: https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.19-rt11.tar.xz Sebastian diff --git a/kernel/futex.c b/kernel/futex.c index d7e14538ac0c4..f4e1167884b07 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -231,7 +231,7 @@ struct futex_q { struct plist_node list; struct task_struct *task; - raw_spinlock_t *lock_ptr; + spinlock_t *lock_ptr; union futex_key key; struct futex_pi_state *pi_state; struct rt_mutex_waiter *rt_waiter; @@ -252,7 +252,7 @@ static const struct futex_q futex_q_init = { */ struct futex_hash_bucket { atomic_t waiters; - raw_spinlock_t lock; + spinlock_t lock; struct plist_head chain; } ____cacheline_aligned_in_smp; @@ -814,13 +814,13 @@ static void get_pi_state(struct futex_pi_state *pi_state) * Drops a reference to the pi_state object and frees or caches it * when the last reference is gone. */ -static struct futex_pi_state *__put_pi_state(struct futex_pi_state *pi_state) +static void put_pi_state(struct futex_pi_state *pi_state) { if (!pi_state) - return NULL; + return; if (!refcount_dec_and_test(&pi_state->refcount)) - return NULL; + return; /* * If pi_state->owner is NULL, the owner is most probably dying @@ -840,7 +840,9 @@ static struct futex_pi_state *__put_pi_state(struct futex_pi_state *pi_state) raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); } - if (!current->pi_state_cache) { + if (current->pi_state_cache) { + kfree(pi_state); + } else { /* * pi_state->list is already empty. * clear pi_state->owner. @@ -849,30 +851,6 @@ static struct futex_pi_state *__put_pi_state(struct futex_pi_state *pi_state) pi_state->owner = NULL; refcount_set(&pi_state->refcount, 1); current->pi_state_cache = pi_state; - pi_state = NULL; - } - return pi_state; -} - -static void put_pi_state(struct futex_pi_state *pi_state) -{ - kfree(__put_pi_state(pi_state)); -} - -static void put_pi_state_atomic(struct futex_pi_state *pi_state, - struct list_head *to_free) -{ - if (__put_pi_state(pi_state)) - list_add(&pi_state->list, to_free); -} - -static void free_pi_state_list(struct list_head *to_free) -{ - struct futex_pi_state *p, *next; - - list_for_each_entry_safe(p, next, to_free, list) { - list_del(&p->list); - kfree(p); } } @@ -889,7 +867,6 @@ void exit_pi_state_list(struct task_struct *curr) struct futex_pi_state *pi_state; struct futex_hash_bucket *hb; union futex_key key = FUTEX_KEY_INIT; - LIST_HEAD(to_free); if (!futex_cmpxchg_enabled) return; @@ -923,7 +900,7 @@ void exit_pi_state_list(struct task_struct *curr) } raw_spin_unlock_irq(&curr->pi_lock); - raw_spin_lock(&hb->lock); + spin_lock(&hb->lock); raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); raw_spin_lock(&curr->pi_lock); /* @@ -933,8 +910,10 @@ void exit_pi_state_list(struct task_struct *curr) if (head->next != next) { /* retain curr->pi_lock for the loop invariant */ raw_spin_unlock(&pi_state->pi_mutex.wait_lock); - raw_spin_unlock(&hb->lock); - put_pi_state_atomic(pi_state, &to_free); + raw_spin_unlock_irq(&curr->pi_lock); + spin_unlock(&hb->lock); + raw_spin_lock_irq(&curr->pi_lock); + put_pi_state(pi_state); continue; } @@ -945,7 +924,7 @@ void exit_pi_state_list(struct task_struct *curr) raw_spin_unlock(&curr->pi_lock); raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); - raw_spin_unlock(&hb->lock); + spin_unlock(&hb->lock); rt_mutex_futex_unlock(&pi_state->pi_mutex); put_pi_state(pi_state); @@ -953,8 +932,6 @@ void exit_pi_state_list(struct task_struct *curr) raw_spin_lock_irq(&curr->pi_lock); } raw_spin_unlock_irq(&curr->pi_lock); - - free_pi_state_list(&to_free); } #endif @@ -1568,21 +1545,21 @@ static inline void double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) { if (hb1 <= hb2) { - raw_spin_lock(&hb1->lock); + spin_lock(&hb1->lock); if (hb1 < hb2) - raw_spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); + spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); } else { /* hb1 > hb2 */ - raw_spin_lock(&hb2->lock); - raw_spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); + spin_lock(&hb2->lock); + spin_lock_nested(&hb1->lock, SINGLE_DEPTH_NESTING); } } static inline void double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) { - raw_spin_unlock(&hb1->lock); + spin_unlock(&hb1->lock); if (hb1 != hb2) - raw_spin_unlock(&hb2->lock); + spin_unlock(&hb2->lock); } /* @@ -1610,7 +1587,7 @@ futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) if (!hb_waiters_pending(hb)) goto out_put_key; - raw_spin_lock(&hb->lock); + spin_lock(&hb->lock); plist_for_each_entry_safe(this, next, &hb->chain, list) { if (match_futex (&this->key, &key)) { @@ -1629,7 +1606,7 @@ futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) } } - raw_spin_unlock(&hb->lock); + spin_unlock(&hb->lock); wake_up_q(&wake_q); out_put_key: put_futex_key(&key); @@ -1936,7 +1913,6 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, struct futex_hash_bucket *hb1, *hb2; struct futex_q *this, *next; DEFINE_WAKE_Q(wake_q); - LIST_HEAD(to_free); if (nr_wake < 0 || nr_requeue < 0) return -EINVAL; @@ -2164,6 +2140,16 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, requeue_pi_wake_futex(this, &key2, hb2); drop_count++; continue; + } else if (ret == -EAGAIN) { + /* + * Waiter was woken by timeout or + * signal and has set pi_blocked_on to + * PI_WAKEUP_INPROGRESS before we + * tried to enqueue it on the rtmutex. + */ + this->pi_state = NULL; + put_pi_state(pi_state); + continue; } else if (ret) { /* * rt_mutex_start_proxy_lock() detected a @@ -2174,7 +2160,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, * object. */ this->pi_state = NULL; - put_pi_state_atomic(pi_state, &to_free); + put_pi_state(pi_state); /* * We stop queueing more waiters and let user * space deal with the mess. @@ -2191,7 +2177,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, * in futex_proxy_trylock_atomic() or in lookup_pi_state(). We * need to drop it here again. */ - put_pi_state_atomic(pi_state, &to_free); + put_pi_state(pi_state); out_unlock: double_unlock_hb(hb1, hb2); @@ -2212,7 +2198,6 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, out_put_key1: put_futex_key(&key1); out: - free_pi_state_list(&to_free); return ret ? ret : task_count; } @@ -2236,7 +2221,7 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q) q->lock_ptr = &hb->lock; - raw_spin_lock(&hb->lock); + spin_lock(&hb->lock); return hb; } @@ -2244,7 +2229,7 @@ static inline void queue_unlock(struct futex_hash_bucket *hb) __releases(&hb->lock) { - raw_spin_unlock(&hb->lock); + spin_unlock(&hb->lock); hb_waiters_dec(hb); } @@ -2283,7 +2268,7 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) __releases(&hb->lock) { __queue_me(q, hb); - raw_spin_unlock(&hb->lock); + spin_unlock(&hb->lock); } /** @@ -2299,41 +2284,41 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb) */ static int unqueue_me(struct futex_q *q) { - raw_spinlock_t *lock_ptr; + spinlock_t *lock_ptr; int ret = 0; /* In the common case we don't take the spinlock, which is nice. */ retry: /* - * q->lock_ptr can change between this read and the following - * raw_spin_lock. Use READ_ONCE to forbid the compiler from reloading - * q->lock_ptr and optimizing lock_ptr out of the logic below. + * q->lock_ptr can change between this read and the following spin_lock. + * Use READ_ONCE to forbid the compiler from reloading q->lock_ptr and + * optimizing lock_ptr out of the logic below. */ lock_ptr = READ_ONCE(q->lock_ptr); if (lock_ptr != NULL) { - raw_spin_lock(lock_ptr); + spin_lock(lock_ptr); /* * q->lock_ptr can change between reading it and - * raw_spin_lock(), causing us to take the wrong lock. This + * spin_lock(), causing us to take the wrong lock. This * corrects the race condition. * * Reasoning goes like this: if we have the wrong lock, * q->lock_ptr must have changed (maybe several times) - * between reading it and the raw_spin_lock(). It can - * change again after the raw_spin_lock() but only if it was - * already changed before the raw_spin_lock(). It cannot, + * between reading it and the spin_lock(). It can + * change again after the spin_lock() but only if it was + * already changed before the spin_lock(). It cannot, * however, change back to the original value. Therefore * we can detect whether we acquired the correct lock. */ if (unlikely(lock_ptr != q->lock_ptr)) { - raw_spin_unlock(lock_ptr); + spin_unlock(lock_ptr); goto retry; } __unqueue_futex(q); BUG_ON(q->pi_state); - raw_spin_unlock(lock_ptr); + spin_unlock(lock_ptr); ret = 1; } @@ -2349,16 +2334,13 @@ static int unqueue_me(struct futex_q *q) static void unqueue_me_pi(struct futex_q *q) __releases(q->lock_ptr) { - struct futex_pi_state *ps; - __unqueue_futex(q); BUG_ON(!q->pi_state); - ps = __put_pi_state(q->pi_state); + put_pi_state(q->pi_state); q->pi_state = NULL; - raw_spin_unlock(q->lock_ptr); - kfree(ps); + spin_unlock(q->lock_ptr); } static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, @@ -2491,7 +2473,7 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, */ handle_err: raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); - raw_spin_unlock(q->lock_ptr); + spin_unlock(q->lock_ptr); switch (err) { case -EFAULT: @@ -2509,7 +2491,7 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, break; } - raw_spin_lock(q->lock_ptr); + spin_lock(q->lock_ptr); raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); /* @@ -2605,7 +2587,7 @@ static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q, /* * The task state is guaranteed to be set before another task can * wake it. set_current_state() is implemented using smp_store_mb() and - * queue_me() calls raw_spin_unlock() upon completion, both serializing + * queue_me() calls spin_unlock() upon completion, both serializing * access to the hash list and forcing another memory barrier. */ set_current_state(TASK_INTERRUPTIBLE); @@ -2896,7 +2878,15 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, * before __rt_mutex_start_proxy_lock() is done. */ raw_spin_lock_irq(&q.pi_state->pi_mutex.wait_lock); - raw_spin_unlock(q.lock_ptr); + /* + * the migrate_disable() here disables migration in the in_atomic() fast + * path which is enabled again in the following spin_unlock(). We have + * one migrate_disable() pending in the slow-path which is reversed + * after the raw_spin_unlock_irq() where we leave the atomic context. + */ + migrate_disable(); + + spin_unlock(q.lock_ptr); /* * __rt_mutex_start_proxy_lock() unconditionally enqueues the @rt_waiter * such that futex_unlock_pi() is guaranteed to observe the waiter when @@ -2904,6 +2894,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, */ ret = __rt_mutex_start_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter, current); raw_spin_unlock_irq(&q.pi_state->pi_mutex.wait_lock); + migrate_enable(); if (ret) { if (ret == 1) @@ -2917,7 +2908,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, ret = rt_mutex_wait_proxy_lock(&q.pi_state->pi_mutex, to, &rt_waiter); cleanup: - raw_spin_lock(q.lock_ptr); + spin_lock(q.lock_ptr); /* * If we failed to acquire the lock (deadlock/signal/timeout), we must * first acquire the hb->lock before removing the lock from the @@ -3018,7 +3009,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) return ret; hb = hash_futex(&key); - raw_spin_lock(&hb->lock); + spin_lock(&hb->lock); /* * Check waiters first. We do not trust user space values at @@ -3052,10 +3043,19 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) * rt_waiter. Also see the WARN in wake_futex_pi(). */ raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock); - raw_spin_unlock(&hb->lock); + /* + * Magic trickery for now to make the RT migrate disable + * logic happy. The following spin_unlock() happens with + * interrupts disabled so the internal migrate_enable() + * won't undo the migrate_disable() which was issued when + * locking hb->lock. + */ + migrate_disable(); + spin_unlock(&hb->lock); /* drops pi_state->pi_mutex.wait_lock */ ret = wake_futex_pi(uaddr, uval, pi_state); + migrate_enable(); put_pi_state(pi_state); @@ -3091,7 +3091,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) * owner. */ if ((ret = cmpxchg_futex_value_locked(&curval, uaddr, uval, 0))) { - raw_spin_unlock(&hb->lock); + spin_unlock(&hb->lock); switch (ret) { case -EFAULT: goto pi_faulted; @@ -3111,7 +3111,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) ret = (curval == uval) ? 0 : -EAGAIN; out_unlock: - raw_spin_unlock(&hb->lock); + spin_unlock(&hb->lock); out_putkey: put_futex_key(&key); return ret; @@ -3227,7 +3227,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, struct hrtimer_sleeper timeout, *to = NULL; struct futex_pi_state *pi_state = NULL; struct rt_mutex_waiter rt_waiter; - struct futex_hash_bucket *hb; + struct futex_hash_bucket *hb, *hb2; union futex_key key2 = FUTEX_KEY_INIT; struct futex_q q = futex_q_init; int res, ret; @@ -3285,20 +3285,55 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, /* Queue the futex_q, drop the hb lock, wait for wakeup. */ futex_wait_queue_me(hb, &q, to); - raw_spin_lock(&hb->lock); - ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to); - raw_spin_unlock(&hb->lock); - if (ret) - goto out_put_keys; + /* + * On RT we must avoid races with requeue and trying to block + * on two mutexes (hb->lock and uaddr2's rtmutex) by + * serializing access to pi_blocked_on with pi_lock. + */ + raw_spin_lock_irq(¤t->pi_lock); + if (current->pi_blocked_on) { + /* + * We have been requeued or are in the process of + * being requeued. + */ + raw_spin_unlock_irq(¤t->pi_lock); + } else { + /* + * Setting pi_blocked_on to PI_WAKEUP_INPROGRESS + * prevents a concurrent requeue from moving us to the + * uaddr2 rtmutex. After that we can safely acquire + * (and possibly block on) hb->lock. + */ + current->pi_blocked_on = PI_WAKEUP_INPROGRESS; + raw_spin_unlock_irq(¤t->pi_lock); + + spin_lock(&hb->lock); + + /* + * Clean up pi_blocked_on. We might leak it otherwise + * when we succeeded with the hb->lock in the fast + * path. + */ + raw_spin_lock_irq(¤t->pi_lock); + current->pi_blocked_on = NULL; + raw_spin_unlock_irq(¤t->pi_lock); + + ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to); + spin_unlock(&hb->lock); + if (ret) + goto out_put_keys; + } /* - * In order for us to be here, we know our q.key == key2, and since - * we took the hb->lock above, we also know that futex_requeue() has - * completed and we no longer have to concern ourselves with a wakeup - * race with the atomic proxy lock acquisition by the requeue code. The - * futex_requeue dropped our key1 reference and incremented our key2 - * reference count. + * In order to be here, we have either been requeued, are in + * the process of being requeued, or requeue successfully + * acquired uaddr2 on our behalf. If pi_blocked_on was + * non-null above, we may be racing with a requeue. Do not + * rely on q->lock_ptr to be hb2->lock until after blocking on + * hb->lock or hb2->lock. The futex_requeue dropped our key1 + * reference and incremented our key2 reference count. */ + hb2 = hash_futex(&key2); /* Check if the requeue code acquired the second futex for us. */ if (!q.rt_waiter) { @@ -3307,9 +3342,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, * did a lock-steal - fix up the PI-state in that case. */ if (q.pi_state && (q.pi_state->owner != current)) { - struct futex_pi_state *ps_free; - - raw_spin_lock(q.lock_ptr); + spin_lock(&hb2->lock); + BUG_ON(&hb2->lock != q.lock_ptr); ret = fixup_pi_state_owner(uaddr2, &q, current); if (ret && rt_mutex_owner(&q.pi_state->pi_mutex) == current) { pi_state = q.pi_state; @@ -3319,9 +3353,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, * Drop the reference to the pi state which * the requeue_pi() code acquired for us. */ - ps_free = __put_pi_state(q.pi_state); - raw_spin_unlock(q.lock_ptr); - kfree(ps_free); + put_pi_state(q.pi_state); + spin_unlock(&hb2->lock); } } else { struct rt_mutex *pi_mutex; @@ -3335,7 +3368,8 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, pi_mutex = &q.pi_state->pi_mutex; ret = rt_mutex_wait_proxy_lock(pi_mutex, to, &rt_waiter); - raw_spin_lock(q.lock_ptr); + spin_lock(&hb2->lock); + BUG_ON(&hb2->lock != q.lock_ptr); if (ret && !rt_mutex_cleanup_proxy_lock(pi_mutex, &rt_waiter)) ret = 0; @@ -3960,7 +3994,7 @@ static int __init futex_init(void) for (i = 0; i < futex_hashsize; i++) { atomic_set(&futex_queues[i].waiters, 0); plist_head_init(&futex_queues[i].chain); - raw_spin_lock_init(&futex_queues[i].lock); + spin_lock_init(&futex_queues[i].lock); } return 0; diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 5ccbb45131e5d..bb5c09c49c504 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -143,6 +143,12 @@ static void fixup_rt_mutex_waiters(struct rt_mutex *lock) WRITE_ONCE(*p, owner & ~RT_MUTEX_HAS_WAITERS); } +static int rt_mutex_real_waiter(struct rt_mutex_waiter *waiter) +{ + return waiter && waiter != PI_WAKEUP_INPROGRESS && + waiter != PI_REQUEUE_INPROGRESS; +} + /* * We can speed up the acquire/release, if there's no debugging state to be * set up. @@ -416,7 +422,8 @@ int max_lock_depth = 1024; static inline struct rt_mutex *task_blocked_on_lock(struct task_struct *p) { - return p->pi_blocked_on ? p->pi_blocked_on->lock : NULL; + return rt_mutex_real_waiter(p->pi_blocked_on) ? + p->pi_blocked_on->lock : NULL; } /* @@ -552,7 +559,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task, * reached or the state of the chain has changed while we * dropped the locks. */ - if (!waiter) + if (!rt_mutex_real_waiter(waiter)) goto out_unlock_pi; /* @@ -1322,6 +1329,22 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock, return -EDEADLK; raw_spin_lock(&task->pi_lock); + /* + * In the case of futex requeue PI, this will be a proxy + * lock. The task will wake unaware that it is enqueueed on + * this lock. Avoid blocking on two locks and corrupting + * pi_blocked_on via the PI_WAKEUP_INPROGRESS + * flag. futex_wait_requeue_pi() sets this when it wakes up + * before requeue (due to a signal or timeout). Do not enqueue + * the task if PI_WAKEUP_INPROGRESS is set. + */ + if (task != current && task->pi_blocked_on == PI_WAKEUP_INPROGRESS) { + raw_spin_unlock(&task->pi_lock); + return -EAGAIN; + } + + BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on)); + waiter->task = task; waiter->lock = lock; waiter->prio = task->prio; @@ -1345,7 +1368,7 @@ static int task_blocks_on_rt_mutex(struct rt_mutex *lock, rt_mutex_enqueue_pi(owner, waiter); rt_mutex_adjust_prio(owner); - if (owner->pi_blocked_on) + if (rt_mutex_real_waiter(owner->pi_blocked_on)) chain_walk = 1; } else if (rt_mutex_cond_detect_deadlock(waiter, chwalk)) { chain_walk = 1; @@ -1445,7 +1468,7 @@ static void remove_waiter(struct rt_mutex *lock, { bool is_top_waiter = (waiter == rt_mutex_top_waiter(lock)); struct task_struct *owner = rt_mutex_owner(lock); - struct rt_mutex *next_lock; + struct rt_mutex *next_lock = NULL; lockdep_assert_held(&lock->wait_lock); @@ -1471,7 +1494,8 @@ static void remove_waiter(struct rt_mutex *lock, rt_mutex_adjust_prio(owner); /* Store the lock on which owner is blocked or NULL */ - next_lock = task_blocked_on_lock(owner); + if (rt_mutex_real_waiter(owner->pi_blocked_on)) + next_lock = task_blocked_on_lock(owner); raw_spin_unlock(&owner->pi_lock); @@ -1507,7 +1531,8 @@ void rt_mutex_adjust_pi(struct task_struct *task) raw_spin_lock_irqsave(&task->pi_lock, flags); waiter = task->pi_blocked_on; - if (!waiter || rt_mutex_waiter_equal(waiter, task_to_waiter(task))) { + if (!rt_mutex_real_waiter(waiter) || + rt_mutex_waiter_equal(waiter, task_to_waiter(task))) { raw_spin_unlock_irqrestore(&task->pi_lock, flags); return; } @@ -2296,6 +2321,26 @@ void rt_mutex_proxy_unlock(struct rt_mutex *lock, rt_mutex_set_owner(lock, NULL); } +static void fixup_rt_mutex_blocked(struct rt_mutex *lock) +{ + struct task_struct *tsk = current; + /* + * RT has a problem here when the wait got interrupted by a timeout + * or a signal. task->pi_blocked_on is still set. The task must + * acquire the hash bucket lock when returning from this function. + * + * If the hash bucket lock is contended then the + * BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on)) in + * task_blocks_on_rt_mutex() will trigger. This can be avoided by + * clearing task->pi_blocked_on which removes the task from the + * boosting chain of the rtmutex. That's correct because the task + * is not longer blocked on it. + */ + raw_spin_lock(&tsk->pi_lock); + tsk->pi_blocked_on = NULL; + raw_spin_unlock(&tsk->pi_lock); +} + /** * __rt_mutex_start_proxy_lock() - Start lock acquisition for another task * @lock: the rt_mutex to take @@ -2326,6 +2371,34 @@ int __rt_mutex_start_proxy_lock(struct rt_mutex *lock, if (try_to_take_rt_mutex(lock, task, NULL)) return 1; +#ifdef CONFIG_PREEMPT_RT_FULL + /* + * In PREEMPT_RT there's an added race. + * If the task, that we are about to requeue, times out, + * it can set the PI_WAKEUP_INPROGRESS. This tells the requeue + * to skip this task. But right after the task sets + * its pi_blocked_on to PI_WAKEUP_INPROGRESS it can then + * block on the spin_lock(&hb->lock), which in RT is an rtmutex. + * This will replace the PI_WAKEUP_INPROGRESS with the actual + * lock that it blocks on. We *must not* place this task + * on this proxy lock in that case. + * + * To prevent this race, we first take the task's pi_lock + * and check if it has updated its pi_blocked_on. If it has, + * we assume that it woke up and we return -EAGAIN. + * Otherwise, we set the task's pi_blocked_on to + * PI_REQUEUE_INPROGRESS, so that if the task is waking up + * it will know that we are in the process of requeuing it. + */ + raw_spin_lock(&task->pi_lock); + if (task->pi_blocked_on) { + raw_spin_unlock(&task->pi_lock); + return -EAGAIN; + } + task->pi_blocked_on = PI_REQUEUE_INPROGRESS; + raw_spin_unlock(&task->pi_lock); +#endif + /* We enforce deadlock detection for futexes */ ret = task_blocks_on_rt_mutex(lock, waiter, task, RT_MUTEX_FULL_CHAINWALK); @@ -2340,6 +2413,9 @@ int __rt_mutex_start_proxy_lock(struct rt_mutex *lock, ret = 0; } + if (ret) + fixup_rt_mutex_blocked(lock); + debug_rt_mutex_print_deadlock(waiter); return ret; @@ -2420,7 +2496,6 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock, struct hrtimer_sleeper *to, struct rt_mutex_waiter *waiter) { - struct task_struct *tsk = current; int ret; raw_spin_lock_irq(&lock->wait_lock); @@ -2432,23 +2507,8 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock, * have to fix that up. */ fixup_rt_mutex_waiters(lock); - /* - * RT has a problem here when the wait got interrupted by a timeout - * or a signal. task->pi_blocked_on is still set. The task must - * acquire the hash bucket lock when returning from this function. - * - * If the hash bucket lock is contended then the - * BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on)) in - * task_blocks_on_rt_mutex() will trigger. This can be avoided by - * clearing task->pi_blocked_on which removes the task from the - * boosting chain of the rtmutex. That's correct because the task - * is not longer blocked on it. - */ - if (ret) { - raw_spin_lock(&tsk->pi_lock); - tsk->pi_blocked_on = NULL; - raw_spin_unlock(&tsk->pi_lock); - } + if (ret) + fixup_rt_mutex_blocked(lock); raw_spin_unlock_irq(&lock->wait_lock); diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h index 758dc43872e5b..546aaf058b9ec 100644 --- a/kernel/locking/rtmutex_common.h +++ b/kernel/locking/rtmutex_common.h @@ -132,6 +132,9 @@ enum rtmutex_chainwalk { /* * PI-futex support (proxy locking functions, etc.): */ +#define PI_WAKEUP_INPROGRESS ((struct rt_mutex_waiter *) 1) +#define PI_REQUEUE_INPROGRESS ((struct rt_mutex_waiter *) 2) + extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock); extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock, struct task_struct *proxy_owner); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 58c545a528b3b..9d9523431178b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1436,6 +1436,9 @@ static int syslog_print_all(char __user *buf, int size, bool clear) break; } + if (len + textlen > size) + break; + if (copy_to_user(buf + len, text, textlen)) len = -EFAULT; else @@ -3075,7 +3078,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, ret = prb_iter_next(&iter, msgbuf, PRINTK_RECORD_MAX, &seq); if (ret == 0) { break; - } else if (ret < 0) { + } else if (ret < 0 || seq >= end_seq) { prb_iter_init(&iter, &printk_rb, &seq); goto retry; } diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c index 60ba93fc42ce3..bd95716532889 100644 --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -23,7 +23,7 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2) * Kernel threads bound to a single CPU can safely use * smp_processor_id(): */ - if (cpumask_equal(current->cpus_ptr, cpumask_of(this_cpu))) + if (current->nr_cpus_allowed == 1) goto out; /* diff --git a/lib/ubsan.c b/lib/ubsan.c index e7d31735950de..39d5952c42733 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -140,25 +140,21 @@ static void val_to_string(char *str, size_t size, struct type_descriptor *type, } } -static DEFINE_SPINLOCK(report_lock); - -static void ubsan_prologue(struct source_location *location, - unsigned long *flags) +static void ubsan_prologue(struct source_location *location) { current->in_ubsan++; - spin_lock_irqsave(&report_lock, *flags); pr_err("========================================" "========================================\n"); print_source_location("UBSAN: Undefined behaviour in", location); } -static void ubsan_epilogue(unsigned long *flags) +static void ubsan_epilogue(void) { dump_stack(); pr_err("========================================" "========================================\n"); - spin_unlock_irqrestore(&report_lock, *flags); + current->in_ubsan--; } @@ -167,14 +163,13 @@ static void handle_overflow(struct overflow_data *data, void *lhs, { struct type_descriptor *type = data->type; - unsigned long flags; char lhs_val_str[VALUE_LENGTH]; char rhs_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); @@ -186,7 +181,7 @@ static void handle_overflow(struct overflow_data *data, void *lhs, rhs_val_str, type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } void __ubsan_handle_add_overflow(struct overflow_data *data, @@ -214,20 +209,19 @@ EXPORT_SYMBOL(__ubsan_handle_mul_overflow); void __ubsan_handle_negate_overflow(struct overflow_data *data, void *old_val) { - unsigned long flags; char old_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); pr_err("negation of %s cannot be represented in type %s:\n", old_val_str, data->type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_negate_overflow); @@ -235,13 +229,12 @@ EXPORT_SYMBOL(__ubsan_handle_negate_overflow); void __ubsan_handle_divrem_overflow(struct overflow_data *data, void *lhs, void *rhs) { - unsigned long flags; char rhs_val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); @@ -251,58 +244,52 @@ void __ubsan_handle_divrem_overflow(struct overflow_data *data, else pr_err("division by zero\n"); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); static void handle_null_ptr_deref(struct type_mismatch_data_common *data) { - unsigned long flags; - if (suppress_report(data->location)) return; - ubsan_prologue(data->location, &flags); + ubsan_prologue(data->location); pr_err("%s null pointer of type %s\n", type_check_kinds[data->type_check_kind], data->type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } static void handle_misaligned_access(struct type_mismatch_data_common *data, unsigned long ptr) { - unsigned long flags; - if (suppress_report(data->location)) return; - ubsan_prologue(data->location, &flags); + ubsan_prologue(data->location); pr_err("%s misaligned address %p for type %s\n", type_check_kinds[data->type_check_kind], (void *)ptr, data->type->type_name); pr_err("which requires %ld byte alignment\n", data->alignment); - ubsan_epilogue(&flags); + ubsan_epilogue(); } static void handle_object_size_mismatch(struct type_mismatch_data_common *data, unsigned long ptr) { - unsigned long flags; - if (suppress_report(data->location)) return; - ubsan_prologue(data->location, &flags); + ubsan_prologue(data->location); pr_err("%s address %p with insufficient space\n", type_check_kinds[data->type_check_kind], (void *) ptr); pr_err("for an object of type %s\n", data->type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, @@ -351,25 +338,23 @@ EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index) { - unsigned long flags; char index_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(index_str, sizeof(index_str), data->index_type, index); pr_err("index %s is out of range for type %s\n", index_str, data->array_type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, void *lhs, void *rhs) { - unsigned long flags; struct type_descriptor *rhs_type = data->rhs_type; struct type_descriptor *lhs_type = data->lhs_type; char rhs_str[VALUE_LENGTH]; @@ -378,7 +363,7 @@ void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); @@ -401,18 +386,16 @@ void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, lhs_str, rhs_str, lhs_type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); void __ubsan_handle_builtin_unreachable(struct unreachable_data *data) { - unsigned long flags; - - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); pr_err("calling __builtin_unreachable()\n"); - ubsan_epilogue(&flags); + ubsan_epilogue(); panic("can't return from __builtin_unreachable()"); } EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); @@ -420,19 +403,18 @@ EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, void *val) { - unsigned long flags; char val_str[VALUE_LENGTH]; if (suppress_report(&data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(&data->location); val_to_string(val_str, sizeof(val_str), data->type, val); pr_err("load of value %s is not a valid value for type %s\n", val_str, data->type->type_name); - ubsan_epilogue(&flags); + ubsan_epilogue(); } EXPORT_SYMBOL(__ubsan_handle_load_invalid_value); diff --git a/localversion-rt b/localversion-rt index d79dde624aaac..05c35cb580779 100644 --- a/localversion-rt +++ b/localversion-rt @@ -1 +1 @@ --rt10 +-rt11 diff --git a/mm/kmemleak.c b/mm/kmemleak.c index aaee59c0306a8..355dd95d0611f 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -135,7 +135,7 @@ struct kmemleak_scan_area { * (use_count) and freed using the RCU mechanism. */ struct kmemleak_object { - spinlock_t lock; + raw_spinlock_t lock; unsigned int flags; /* object status flags */ struct list_head object_list; struct list_head gray_list; @@ -560,7 +560,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size, INIT_LIST_HEAD(&object->object_list); INIT_LIST_HEAD(&object->gray_list); INIT_HLIST_HEAD(&object->area_list); - spin_lock_init(&object->lock); + raw_spin_lock_init(&object->lock); atomic_set(&object->use_count, 1); object->flags = OBJECT_ALLOCATED; object->pointer = ptr; @@ -642,9 +642,9 @@ static void __delete_object(struct kmemleak_object *object) * Locking here also ensures that the corresponding memory block * cannot be freed when it is being scanned. */ - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); object->flags &= ~OBJECT_ALLOCATED; - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } @@ -716,9 +716,9 @@ static void paint_it(struct kmemleak_object *object, int color) { unsigned long flags; - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); __paint_it(object, color); - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); } static void paint_ptr(unsigned long ptr, int color) @@ -778,7 +778,7 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp) goto out; } - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); if (size == SIZE_MAX) { size = object->pointer + object->size - ptr; } else if (ptr + size > object->pointer + object->size) { @@ -794,7 +794,7 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp) hlist_add_head(&area->node, &object->area_list); out_unlock: - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); out: put_object(object); } @@ -817,9 +817,9 @@ static void object_set_excess_ref(unsigned long ptr, unsigned long excess_ref) return; } - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); object->excess_ref = excess_ref; - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } @@ -839,9 +839,9 @@ static void object_no_scan(unsigned long ptr) return; } - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); object->flags |= OBJECT_NO_SCAN; - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } @@ -902,11 +902,11 @@ static void early_alloc(struct early_log *log) log->min_count, GFP_ATOMIC); if (!object) goto out; - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); for (i = 0; i < log->trace_len; i++) object->trace[i] = log->trace[i]; object->trace_len = log->trace_len; - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); out: rcu_read_unlock(); } @@ -1096,9 +1096,9 @@ void __ref kmemleak_update_trace(const void *ptr) return; } - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); object->trace_len = __save_stack_trace(object->trace); - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } @@ -1346,7 +1346,7 @@ static void scan_block(void *_start, void *_end, * previously acquired in scan_object(). These locks are * enclosed by scan_mutex. */ - spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING); + raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING); /* only pass surplus references (object already gray) */ if (color_gray(object)) { excess_ref = object->excess_ref; @@ -1355,7 +1355,7 @@ static void scan_block(void *_start, void *_end, excess_ref = 0; update_refs(object); } - spin_unlock(&object->lock); + raw_spin_unlock(&object->lock); if (excess_ref) { object = lookup_object(excess_ref, 0); @@ -1364,9 +1364,9 @@ static void scan_block(void *_start, void *_end, if (object == scanned) /* circular reference, ignore */ continue; - spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING); + raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING); update_refs(object); - spin_unlock(&object->lock); + raw_spin_unlock(&object->lock); } } raw_spin_unlock_irqrestore(&kmemleak_lock, flags); @@ -1402,7 +1402,7 @@ static void scan_object(struct kmemleak_object *object) * Once the object->lock is acquired, the corresponding memory block * cannot be freed (the same lock is acquired in delete_object). */ - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); if (object->flags & OBJECT_NO_SCAN) goto out; if (!(object->flags & OBJECT_ALLOCATED)) @@ -1421,9 +1421,9 @@ static void scan_object(struct kmemleak_object *object) if (start >= end) break; - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); cond_resched(); - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); } while (object->flags & OBJECT_ALLOCATED); } else hlist_for_each_entry(area, &object->area_list, node) @@ -1431,7 +1431,7 @@ static void scan_object(struct kmemleak_object *object) (void *)(area->start + area->size), object); out: - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); } /* @@ -1484,7 +1484,7 @@ static void kmemleak_scan(void) /* prepare the kmemleak_object's */ rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); #ifdef DEBUG /* * With a few exceptions there should be a maximum of @@ -1501,7 +1501,7 @@ static void kmemleak_scan(void) if (color_gray(object) && get_object(object)) list_add_tail(&object->gray_list, &gray_list); - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); } rcu_read_unlock(); @@ -1569,14 +1569,14 @@ static void kmemleak_scan(void) */ rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); if (color_white(object) && (object->flags & OBJECT_ALLOCATED) && update_checksum(object) && get_object(object)) { /* color it gray temporarily */ object->count = object->min_count; list_add_tail(&object->gray_list, &gray_list); } - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); } rcu_read_unlock(); @@ -1596,7 +1596,7 @@ static void kmemleak_scan(void) */ rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); if (unreferenced_object(object) && !(object->flags & OBJECT_REPORTED)) { object->flags |= OBJECT_REPORTED; @@ -1606,7 +1606,7 @@ static void kmemleak_scan(void) new_leaks++; } - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); } rcu_read_unlock(); @@ -1758,10 +1758,10 @@ static int kmemleak_seq_show(struct seq_file *seq, void *v) struct kmemleak_object *object = v; unsigned long flags; - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) print_unreferenced(seq, object); - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); return 0; } @@ -1791,9 +1791,9 @@ static int dump_str_object_info(const char *str) return -EINVAL; } - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); dump_object_info(object); - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); return 0; @@ -1812,11 +1812,11 @@ static void kmemleak_clear(void) rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { - spin_lock_irqsave(&object->lock, flags); + raw_spin_lock_irqsave(&object->lock, flags); if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) __paint_it(object, KMEMLEAK_GREY); - spin_unlock_irqrestore(&object->lock, flags); + raw_spin_unlock_irqrestore(&object->lock, flags); } rcu_read_unlock();