summaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2019-11-26 16:02:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-11-26 16:02:40 -0800
commit168829ad09ca9cdfdc664b2110d0e3569932c12d (patch)
tree1b6351ab5766a272dec1fc08f77272a199bba978 /kernel
parent1ae78780eda54023a0fb49ee743dbba39da148e0 (diff)
parent500543c53a54134ced386aed85cd93cf1363f981 (diff)
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - A comprehensive rewrite of the robust/PI futex code's exit handling to fix various exit races. (Thomas Gleixner et al) - Rework the generic REFCOUNT_FULL implementation using atomic_fetch_* operations so that the performance impact of the cmpxchg() loops is mitigated for common refcount operations. With these performance improvements the generic implementation of refcount_t should be good enough for everybody - and this got confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely, leaving the generic implementation enabled unconditionally. (Will Deacon) - Other misc changes, fixes, cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) lkdtm: Remove references to CONFIG_REFCOUNT_FULL locking/refcount: Remove unused 'refcount_error_report()' function locking/refcount: Consolidate implementations of refcount_t locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions locking/refcount: Move saturation warnings out of line locking/refcount: Improve performance of generic REFCOUNT_FULL code locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header locking/refcount: Remove unused refcount_*_checked() variants locking/refcount: Ensure integer operands are treated as signed locking/refcount: Define constants for saturation and max refcount values futex: Prevent exit livelock futex: Provide distinct return value when owner is exiting futex: Add mutex around futex exit futex: Provide state handling for exec() as well futex: Sanitize exit state handling futex: Mark the begin of futex exit explicitly futex: Set task::futex_state to DEAD right after handling futex exit futex: Split futex_mm_release() for exit/exec exit/exec: Seperate mm_release() futex: Replace PF_EXITPIDONE with a state ...
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/stackmap.c2
-rw-r--r--kernel/cpu.c2
-rw-r--r--kernel/exit.c30
-rw-r--r--kernel/fork.c40
-rw-r--r--kernel/futex.c326
-rw-r--r--kernel/locking/lockdep.c7
-rw-r--r--kernel/locking/mutex.c8
-rw-r--r--kernel/locking/rtmutex.c6
-rw-r--r--kernel/locking/rwsem.c10
-rw-r--r--kernel/panic.c11
-rw-r--r--kernel/printk/printk.c10
-rw-r--r--kernel/sched/core.c2
12 files changed, 323 insertions, 131 deletions
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index 173e983619d7..caca752ee5e6 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -339,7 +339,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
* up_read_non_owner(). The rwsem_release() is called
* here to release the lock from lockdep's perspective.
*/
- rwsem_release(&current->mm->mmap_sem.dep_map, 1, _RET_IP_);
+ rwsem_release(&current->mm->mmap_sem.dep_map, _RET_IP_);
}
}
diff --git a/kernel/cpu.c b/kernel/cpu.c
index e2cad3ee2ead..a59cc980adad 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -336,7 +336,7 @@ static void lockdep_acquire_cpus_lock(void)
static void lockdep_release_cpus_lock(void)
{
- rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, 1, _THIS_IP_);
+ rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, _THIS_IP_);
}
/*
diff --git a/kernel/exit.c b/kernel/exit.c
index f2d20ab74422..0bac4b60d5f3 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -437,7 +437,7 @@ static void exit_mm(void)
struct mm_struct *mm = current->mm;
struct core_state *core_state;
- mm_release(current, mm);
+ exit_mm_release(current, mm);
if (!mm)
return;
sync_mm_rss(mm);
@@ -746,32 +746,12 @@ void __noreturn do_exit(long code)
*/
if (unlikely(tsk->flags & PF_EXITING)) {
pr_alert("Fixing recursive fault but reboot is needed!\n");
- /*
- * We can do this unlocked here. The futex code uses
- * this flag just to verify whether the pi state
- * cleanup has been done or not. In the worst case it
- * loops once more. We pretend that the cleanup was
- * done as there is no way to return. Either the
- * OWNER_DIED bit is set by now or we push the blocked
- * task into the wait for ever nirwana as well.
- */
- tsk->flags |= PF_EXITPIDONE;
+ futex_exit_recursive(tsk);
set_current_state(TASK_UNINTERRUPTIBLE);
schedule();
}
exit_signals(tsk); /* sets PF_EXITING */
- /*
- * Ensure that all new tsk->pi_lock acquisitions must observe
- * PF_EXITING. Serializes against futex.c:attach_to_pi_owner().
- */
- smp_mb();
- /*
- * Ensure that we must observe the pi_state in exit_mm() ->
- * mm_release() -> exit_pi_state_list().
- */
- raw_spin_lock_irq(&tsk->pi_lock);
- raw_spin_unlock_irq(&tsk->pi_lock);
if (unlikely(in_atomic())) {
pr_info("note: %s[%d] exited with preempt_count %d\n",
@@ -846,12 +826,6 @@ void __noreturn do_exit(long code)
* Make sure we are holding no locks:
*/
debug_check_no_locks_held();
- /*
- * We can do this unlocked here. The futex code uses this flag
- * just to verify whether the pi state cleanup has been done
- * or not. In the worst case it loops once more.
- */
- tsk->flags |= PF_EXITPIDONE;
if (tsk->io_context)
exit_io_context(tsk);
diff --git a/kernel/fork.c b/kernel/fork.c
index 35f91ee91057..00b64f41c2b4 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1283,24 +1283,8 @@ static int wait_for_vfork_done(struct task_struct *child,
* restoring the old one. . .
* Eric Biederman 10 January 1998
*/
-void mm_release(struct task_struct *tsk, struct mm_struct *mm)
+static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
{
- /* Get rid of any futexes when releasing the mm */
-#ifdef CONFIG_FUTEX
- if (unlikely(tsk->robust_list)) {
- exit_robust_list(tsk);
- tsk->robust_list = NULL;
- }
-#ifdef CONFIG_COMPAT
- if (unlikely(tsk->compat_robust_list)) {
- compat_exit_robust_list(tsk);
- tsk->compat_robust_list = NULL;
- }
-#endif
- if (unlikely(!list_empty(&tsk->pi_state_list)))
- exit_pi_state_list(tsk);
-#endif
-
uprobe_free_utask(tsk);
/* Get rid of any cached register state */
@@ -1333,6 +1317,18 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
complete_vfork_done(tsk);
}
+void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
+{
+ futex_exit_release(tsk);
+ mm_release(tsk, mm);
+}
+
+void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
+{
+ futex_exec_release(tsk);
+ mm_release(tsk, mm);
+}
+
/**
* dup_mm() - duplicates an existing mm structure
* @tsk: the task_struct with which the new mm will be associated.
@@ -2124,14 +2120,8 @@ static __latent_entropy struct task_struct *copy_process(
#ifdef CONFIG_BLOCK
p->plug = NULL;
#endif
-#ifdef CONFIG_FUTEX
- p->robust_list = NULL;
-#ifdef CONFIG_COMPAT
- p->compat_robust_list = NULL;
-#endif
- INIT_LIST_HEAD(&p->pi_state_list);
- p->pi_state_cache = NULL;
-#endif
+ futex_init_task(p);
+
/*
* sigaltstack should be cleared when sharing the same VM
*/
diff --git a/kernel/futex.c b/kernel/futex.c
index bd18f60e4c6c..03c518e9747e 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -325,6 +325,12 @@ static inline bool should_fail_futex(bool fshared)
}
#endif /* CONFIG_FAIL_FUTEX */
+#ifdef CONFIG_COMPAT
+static void compat_exit_robust_list(struct task_struct *curr);
+#else
+static inline void compat_exit_robust_list(struct task_struct *curr) { }
+#endif
+
static inline void futex_get_mm(union futex_key *key)
{
mmgrab(key->private.mm);
@@ -890,7 +896,7 @@ static void put_pi_state(struct futex_pi_state *pi_state)
* Kernel cleans up PI-state, but userspace is likely hosed.
* (Robust-futex cleanup is separate and might save the day for userspace.)
*/
-void exit_pi_state_list(struct task_struct *curr)
+static void exit_pi_state_list(struct task_struct *curr)
{
struct list_head *next, *head = &curr->pi_state_list;
struct futex_pi_state *pi_state;
@@ -960,7 +966,8 @@ void exit_pi_state_list(struct task_struct *curr)
}
raw_spin_unlock_irq(&curr->pi_lock);
}
-
+#else
+static inline void exit_pi_state_list(struct task_struct *curr) { }
#endif
/*
@@ -1169,16 +1176,47 @@ out_error:
return ret;
}
+/**
+ * wait_for_owner_exiting - Block until the owner has exited
+ * @exiting: Pointer to the exiting task
+ *
+ * Caller must hold a refcount on @exiting.
+ */
+static void wait_for_owner_exiting(int ret, struct task_struct *exiting)
+{
+ if (ret != -EBUSY) {
+ WARN_ON_ONCE(exiting);
+ return;
+ }
+
+ if (WARN_ON_ONCE(ret == -EBUSY && !exiting))
+ return;
+
+ mutex_lock(&exiting->futex_exit_mutex);
+ /*
+ * No point in doing state checking here. If the waiter got here
+ * while the task was in exec()->exec_futex_release() then it can
+ * have any FUTEX_STATE_* value when the waiter has acquired the
+ * mutex. OK, if running, EXITING or DEAD if it reached exit()
+ * already. Highly unlikely and not a problem. Just one more round
+ * through the futex maze.
+ */
+ mutex_unlock(&exiting->futex_exit_mutex);
+
+ put_task_struct(exiting);
+}
+
static int handle_exit_race(u32 __user *uaddr, u32 uval,
struct task_struct *tsk)
{
u32 uval2;
/*
- * If PF_EXITPIDONE is not yet set, then try again.
+ * If the futex exit state is not yet FUTEX_STATE_DEAD, tell the
+ * caller that the alleged owner is busy.
*/
- if (tsk && !(tsk->flags & PF_EXITPIDONE))
- return -EAGAIN;
+ if (tsk && tsk->futex_state != FUTEX_STATE_DEAD)
+ return -EBUSY;
/*
* Reread the user space value to handle the following situation:
@@ -1196,8 +1234,9 @@ static int handle_exit_race(u32 __user *uaddr, u32 uval,
* *uaddr = 0xC0000000; tsk = get_task(PID);
* } if (!tsk->flags & PF_EXITING) {
* ... attach();
- * tsk->flags |= PF_EXITPIDONE; } else {
- * if (!(tsk->flags & PF_EXITPIDONE))
+ * tsk->futex_state = } else {
+ * FUTEX_STATE_DEAD; if (tsk->futex_state !=
+ * FUTEX_STATE_DEAD)
* return -EAGAIN;
* return -ESRCH; <--- FAIL
* }
@@ -1228,7 +1267,8 @@ static int handle_exit_race(u32 __user *uaddr, u32 uval,
* it after doing proper sanity checks.
*/
static int attach_to_pi_owner(u32 __user *uaddr, u32 uval, union futex_key *key,
- struct futex_pi_state **ps)
+ struct futex_pi_state **ps,
+ struct task_struct **exiting)
{
pid_t pid = uval & FUTEX_TID_MASK;
struct futex_pi_state *pi_state;
@@ -1253,22 +1293,33 @@ static int attach_to_pi_owner(u32 __user *uaddr, u32 uval, union futex_key *key,
}
/*
- * We need to look at the task state flags to figure out,
- * whether the task is exiting. To protect against the do_exit
- * change of the task flags, we do this protected by
- * p->pi_lock:
+ * We need to look at the task state to figure out, whether the
+ * task is exiting. To protect against the change of the task state
+ * in futex_exit_release(), we do this protected by p->pi_lock:
*/
raw_spin_lock_irq(&p->pi_lock);
- if (unlikely(p->flags & PF_EXITING)) {
+ if (unlikely(p->futex_state != FUTEX_STATE_OK)) {
/*
- * The task is on the way out. When PF_EXITPIDONE is
- * set, we know that the task has finished the
- * cleanup:
+ * The task is on the way out. When the futex state is
+ * FUTEX_STATE_DEAD, we know that the task has finished
+ * the cleanup:
*/
int ret = handle_exit_race(uaddr, uval, p);
raw_spin_unlock_irq(&p->pi_lock);
- put_task_struct(p);
+ /*
+ * If the owner task is between FUTEX_STATE_EXITING and
+ * FUTEX_STATE_DEAD then store the task pointer and keep
+ * the reference on the task struct. The calling code will
+ * drop all locks, wait for the task to reach
+ * FUTEX_STATE_DEAD and then drop the refcount. This is
+ * required to prevent a live lock when the current task
+ * preempted the exiting task between the two states.
+ */
+ if (ret == -EBUSY)
+ *exiting = p;
+ else
+ put_task_struct(p);
return ret;
}
@@ -1307,7 +1358,8 @@ static int attach_to_pi_owner(u32 __user *uaddr, u32 uval, union futex_key *key,
static int lookup_pi_state(u32 __user *uaddr, u32 uval,
struct futex_hash_bucket *hb,
- union futex_key *key, struct futex_pi_state **ps)
+ union futex_key *key, struct futex_pi_state **ps,
+ struct task_struct **exiting)
{
struct futex_q *top_waiter = futex_top_waiter(hb, key);
@@ -1322,7 +1374,7 @@ static int lookup_pi_state(u32 __user *uaddr, u32 uval,
* We are the first waiter - try to look up the owner based on
* @uval and attach to it.
*/
- return attach_to_pi_owner(uaddr, uval, key, ps);
+ return attach_to_pi_owner(uaddr, uval, key, ps, exiting);
}
static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval)
@@ -1350,6 +1402,8 @@ static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval)
* lookup
* @task: the task to perform the atomic lock work for. This will
* be "current" except in the case of requeue pi.
+ * @exiting: Pointer to store the task pointer of the owner task
+ * which is in the middle of exiting
* @set_waiters: force setting the FUTEX_WAITERS bit (1) or not (0)
*
* Return:
@@ -1358,11 +1412,17 @@ static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval)
* - <0 - error
*
* The hb->lock and futex_key refs shall be held by the caller.
+ *
+ * @exiting is only set when the return value is -EBUSY. If so, this holds
+ * a refcount on the exiting task on return and the caller needs to drop it
+ * after waiting for the exit to complete.
*/
static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
union futex_key *key,
struct futex_pi_state **ps,
- struct task_struct *task, int set_waiters)
+ struct task_struct *task,
+ struct task_struct **exiting,
+ int set_waiters)
{
u32 uval, newval, vpid = task_pid_vnr(task);
struct futex_q *top_waiter;
@@ -1432,7 +1492,7 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
* attach to the owner. If that fails, no harm done, we only
* set the FUTEX_WAITERS bit in the user space variable.
*/
- return attach_to_pi_owner(uaddr, newval, key, ps);
+ return attach_to_pi_owner(uaddr, newval, key, ps, exiting);
}
/**
@@ -1480,7 +1540,7 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q)
/*
* Queue the task for later wakeup for after we've released
- * the hb->lock. wake_q_add() grabs reference to p.
+ * the hb->lock.
*/
wake_q_add_safe(wake_q, p);
}
@@ -1850,6 +1910,8 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
* @key1: the from futex key
* @key2: the to futex key
* @ps: address to store the pi_state pointer
+ * @exiting: Pointer to store the task pointer of the owner task
+ * which is in the middle of exiting
* @set_waiters: force setting the FUTEX_WAITERS bit (1) or not (0)
*
* Try and get the lock on behalf of the top waiter if we can do it atomically.
@@ -1857,16 +1919,20 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
* then direct futex_lock_pi_atomic() to force setting the FUTEX_WAITERS bit.
* hb1 and hb2 must be held by the caller.
*
+ * @exiting is only set when the return value is -EBUSY. If so, this holds
+ * a refcount on the exiting task on return and the caller needs to drop it
+ * after waiting for the exit to complete.
+ *
* Return:
* - 0 - failed to acquire the lock atomically;
* - >0 - acquired the lock, return value is vpid of the top_waiter
* - <0 - error
*/
-static int futex_proxy_trylock_atomic(u32 __user *pifutex,
- struct futex_hash_bucket *hb1,
- struct futex_hash_bucket *hb2,
- union futex_key *key1, union futex_key *key2,
- struct futex_pi_state **ps, int set_waiters)
+static int
+futex_proxy_trylock_atomic(u32 __user *pifutex, struct futex_hash_bucket *hb1,
+ struct futex_hash_bucket *hb2, union futex_key *key1,
+ union futex_key *key2, struct futex_pi_state **ps,
+ struct task_struct **exiting, int set_waiters)
{
struct futex_q *top_waiter = NULL;
u32 curval;
@@ -1903,7 +1969,7 @@ static int futex_proxy_trylock_atomic(u32 __user *pifutex,
*/
vpid = task_pid_vnr(top_waiter->task);
ret = futex_lock_pi_atomic(pifutex, hb2, key2, ps, top_waiter->task,
- set_waiters);
+ exiting, set_waiters);
if (ret == 1) {
requeue_pi_wake_futex(top_waiter, key2, hb2);
return vpid;
@@ -2032,6 +2098,8 @@ retry_private:
}
if (requeue_pi && (task_count - nr_wake < nr_requeue)) {
+ struct task_struct *exiting = NULL;
+
/*
* Attempt to acquire uaddr2 and wake the top waiter. If we
* intend to requeue waiters, force setting the FUTEX_WAITERS
@@ -2039,7 +2107,8 @@ retry_private:
* faults rather in the requeue loop below.
*/
ret = futex_proxy_trylock_atomic(uaddr2, hb1, hb2, &key1,
- &key2, &pi_state, nr_requeue);
+ &key2, &pi_state,
+ &exiting, nr_requeue);
/*
* At this point the top_waiter has either taken uaddr2 or is
@@ -2066,7 +2135,8 @@ retry_private:
* If that call succeeds then we have pi_state and an
* initial refcount on it.
*/
- ret = lookup_pi_state(uaddr2, ret, hb2, &key2, &pi_state);
+ ret = lookup_pi_state(uaddr2, ret, hb2, &key2,
+ &pi_state, &exiting);
}
switch (ret) {
@@ -2084,17 +2154,24 @@ retry_private:
if (!ret)
goto retry;
goto out;
+ case -EBUSY:
case -EAGAIN:
/*
* Two reasons for this:
- * - Owner is exiting and we just wait for the
+ * - EBUSY: Owner is exiting and we just wait for the
* exit to complete.
- * - The user space value changed.
+ * - EAGAIN: The user space value changed.
*/
double_unlock_hb(hb1, hb2);
hb_waiters_dec(hb2);
put_futex_key(&key2);
put_futex_key(&key1);
+ /*
+ * Handle the case where the owner is in the middle of
+ * exiting. Wait for the exit to complete otherwise
+ * this task might loop forever, aka. live lock.
+ */
+ wait_for_owner_exiting(ret, exiting);
cond_resched();
goto retry;
default:
@@ -2801,6 +2878,7 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
{
struct hrtimer_sleeper timeout, *to;
struct futex_pi_state *pi_state = NULL;
+ struct task_struct *exiting = NULL;
struct rt_mutex_waiter rt_waiter;
struct futex_hash_bucket *hb;
struct futex_q q = futex_q_init;
@@ -2822,7 +2900,8 @@ retry:
retry_private:
hb = queue_lock(&q);
- ret = futex_lock_pi_atomic(uaddr, hb, &q.key, &q.pi_state, current, 0);
+ ret = futex_lock_pi_atomic(uaddr, hb, &q.key, &q.pi_state, current,
+ &exiting, 0);
if (unlikely(ret)) {
/*
* Atomic work succeeded and we got the lock,
@@ -2835,15 +2914,22 @@ retry_private:
goto out_unlock_put_key;
case -EFAULT:
goto uaddr_faulted;
+ case -EBUSY:
case -EAGAIN:
/*
* Two reasons for this:
- * - Task is exiting and we just wait for the
+ * - EBUSY: Task is exiting and we just wait for the
* exit to complete.
- * - The user space value changed.
+ * - EAGAIN: The user space value changed.
*/
queue_unlock(hb);
put_futex_key(&q.key);
+ /*
+ * Handle the case where the owner is in the middle of
+ * exiting. Wait for the exit to complete otherwise
+ * this task might loop forever, aka. live lock.
+ */
+ wait_for_owner_exiting(ret, exiting);
cond_resched();
goto retry;
default:
@@ -3452,11 +3538,16 @@ err_unlock:
return ret;
}
+/* Constants for the pending_op argument of handle_futex_death */
+#define HANDLE_DEATH_PENDING true
+#define HANDLE_DEATH_LIST false
+
/*
* Process a futex-list entry, check whether it's owned by the
* dying task, and do notification if so:
*/
-static int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi)
+static int handle_futex_death(u32 __user *uaddr, struct task_struct *curr,
+ bool pi, bool pending_op)
{
u32 uval, uninitialized_var(nval), mval;
int err;
@@ -3469,6 +3560,42 @@ retry:
if (get_user(uval, uaddr))
return -1;
+ /*
+ * Special case for regular (non PI) futexes. The unlock path in
+ * user space has two race scenarios:
+ *
+ * 1. The unlock path releases the user space futex value and
+ * before it can execute the futex() syscall to wake up
+ * waiters it is killed.
+ *
+ * 2. A woken up waiter is killed before it can acquire the
+ * futex in user space.
+ *
+ * In both cases the TID validation below prevents a wakeup of
+ * potential waiters which can cause these waiters to block
+ * forever.
+ *
+ * In both cases the following conditions are met:
+ *
+ * 1) task->robust_list->list_op_pending != NULL
+ * @pending_op == true
+ * 2) User space futex value == 0
+ * 3) Regular futex: @pi == false
+ *
+ * If these conditions are met, it is safe to attempt waking up a
+ * potential waiter without touching the user space futex value and
+ * trying to set the OWNER_DIED bit. The user space futex value is
+ * uncontended and the rest of the user space mutex state is
+ * consistent, so a woken waiter will just take over the
+ * uncontended futex. Setting the OWNER_DIED bit would create
+ * inconsistent state and malfunction of the user space owner died
+ * handling.
+ */
+ if (pending_op && !pi && !uval) {
+ futex_wake(uaddr, 1, 1, FUTEX_BITSET_MATCH_ANY);
+ return 0;
+ }
+
if ((uval & FUTEX_TID_MASK) != task_pid_vnr(curr))
return 0;
@@ -3547,7 +3674,7 @@ static inline int fetch_robust_entry(struct robust_list __user **entry,
*
* We silently return on any sign of list-walking problem.
*/
-void exit_robust_list(struct task_struct *curr)
+static void exit_robust_list(struct task_struct *curr)
{
struct robust_list_head __user *head = curr->robust_list;
struct robust_list __user *entry, *next_entry, *pending;
@@ -3588,10 +3715,11 @@ void exit_robust_list(struct task_struct *curr)
* A pending lock might already be on the list, so
* don't process it twice:
*/
- if (entry != pending)
+ if (entry != pending) {
if (handle_futex_death((void __user *)entry + futex_offset,
- curr, pi))
+ curr, pi, HANDLE_DEATH_LIST))
return;
+ }
if (rc)
return;
entry = next_entry;
@@ -3605,9 +3733,118 @@ void exit_robust_list(struct task_struct *curr)
cond_resched();
}
- if (pending)
+ if (pending) {
handle_futex_death((void __user *)pending + futex_offset,
- curr, pip);
+ curr, pip, HANDLE_DEATH_PENDING);
+ }
+}
+
+static void futex_cleanup(struct task_struct *tsk)
+{
+ if (unlikely(tsk->robust_list)) {
+ exit_robust_list(tsk);
+ tsk->robust_list = NULL;
+ }
+
+#ifdef CONFIG_COMPAT
+ if (unlikely(tsk->compat_robust_list)) {
+ compat_exit_robust_list(tsk);
+ tsk->compat_robust_list = NULL;
+ }
+#endif
+
+ if (unlikely(!list_empty(&tsk->pi_state_list)))
+ exit_pi_state_list(tsk);
+}
+
+/**
+ * futex_exit_recursive - Set the tasks futex state to FUTEX_STATE_DEAD
+ * @tsk: task to set the state on
+ *
+ * Set the futex exit state of the task lockless. The futex waiter code
+ * observes that state when a task is exiting and loops until the task has
+ * actually finished the futex cleanup. The worst case for this is that the
+ * waiter runs through the wait loop until the state becomes visible.
+ *
+ * This is called from the recursive fault handling path in do_exit().
+ *
+ * This is best effort. Either the futex exit code has run already or
+ * not. If the OWNER_DIED bit has been set on the futex then the waiter can
+ * take it over. If not, the problem is pushed back to user space. If the
+ * futex exit code did not run yet, then an already queued waiter might
+ * block forever, but there is nothing which can be done about that.
+ */
+void futex_exit_recursive(struct task_struct *tsk)
+{
+ /* If the state is FUTEX_STATE_EXITING then futex_exit_mutex is held */
+ if (tsk->futex_state == FUTEX_STATE_EXITING)
+ mutex_unlock(&tsk->futex_exit_mutex);
+ tsk->futex_state = FUTEX_STATE_DEAD;
+}
+
+static void futex_cleanup_begin(struct task_struct *tsk)
+{
+ /*
+ * Prevent various race issues against a concurrent incoming waiter
+ * including live locks by forcing the waiter to block on
+ * tsk->futex_exit_mutex when it observes FUTEX_STATE_EXITING in
+ * attach_to_pi_owner().
+ */
+ mutex_lock(&tsk->futex_exit_mutex);
+
+ /*
+ * Switch the state to FUTEX_STATE_EXITING under tsk->pi_lock.
+ *
+ * This ensures that all subsequent checks of tsk->futex_state in
+ * attach_to_pi_owner() must observe FUTEX_STATE_EXITING with
+ * tsk->pi_lock held.
+ *
+ * It guarantees also that a pi_state which was queued right before
+ * the state change under tsk->pi_lock by a concurrent waiter must
+ * be observed in exit_pi_state_list().
+ */
+ raw_spin_lock_irq(&tsk->pi_lock);
+ tsk->futex_state = FUTEX_STATE_EXITING;
+ raw_spin_unlock_irq(&tsk->pi_lock);
+}
+
+static void futex_cleanup_end(struct task_struct *tsk, int state)
+{
+ /*
+ * Lockless store. The only side effect is that an observer might
+ * take another loop until it becomes visible.
+ */
+ tsk->futex_state = state;
+ /*
+ * Drop the exit protection. This unblocks waiters which observed
+ * FUTEX_STATE_EXITING to reevaluate the state.
+ */
+ mutex_unlock(&tsk->futex_exit_mutex);
+}
+
+void futex_exec_release(struct task_struct *tsk)
+{
+ /*
+ * The state handling is done for consistency, but in the case of
+ * exec() there is no way to prevent futher damage as the PID stays
+ * the same. But for the unlikely and arguably buggy case that a
+ * futex is held on exec(), this provides at least as much state
+ * consistency protection which is possible.
+ */
+ futex_cleanup_begin(tsk);
+ futex_cleanup(tsk);
+ /*
+ * Reset the state to FUTEX_STATE_OK. The task is alive and about
+ * exec a new binary.
+ */
+ futex_cleanup_end(tsk, FUTEX_STATE_OK);
+}
+
+void futex_exit_release(struct task_struct *tsk)
+{
+ futex_cleanup_begin(tsk);
+ futex_cleanup(tsk);
+ futex_cleanup_end(tsk, FUTEX_STATE_DEAD);
}
long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
@@ -3737,7 +3974,7 @@ static void __user *futex_uaddr(struct robust_list __user *entry,
*
* We silently return on any sign of list-walking problem.
*/
-void compat_exit_robust_list(struct task_struct *curr)
+static void compat_exit_robust_list(struct task_struct *curr)
{
struct compat_robust_list_head __user *head = curr->compat_robust_list;
struct robust_list __user *entry, *next_entry, *pending;
@@ -3784,7 +4021,8 @@ void compat_exit_robust_list(struct task_struct *curr)
if (entry != pending) {
void __user *uaddr = futex_uaddr(entry, futex_offset);
- if (handle_futex_death(uaddr, curr, pi))
+ if (handle_futex_death(uaddr, curr, pi,
+ HANDLE_DEATH_LIST))
return;
}
if (rc)
@@ -3803,7 +4041,7 @@ void compat_exit_robust_list(struct task_struct *curr)
if (pending) {
void __user *uaddr = futex_uaddr(pending, futex_offset);
- handle_futex_death(uaddr, curr, pip);
+ handle_futex_death(uaddr, curr, pip, HANDLE_DEATH_PENDING);
}
}
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 233459c03b5a..32282e7112d3 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4208,11 +4208,9 @@ static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
}
/*
- * Remove the lock to the list of currently held locks - this gets
+ * Remove the lock from the list of currently held locks - this gets
* called on mutex_unlock()/spin_unlock*() (or on a failed
* mutex_lock_interruptible()).
- *
- * @nested is an hysterical artifact, needs a tree wide cleanup.
*/
static int
__lock_release(struct lockdep_map *lock, unsigned long ip)
@@ -4491,8 +4489,7 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
}
EXPORT_SYMBOL_GPL(lock_acquire);
-void lock_release(struct lockdep_map *lock, int nested,
- unsigned long ip)
+void lock_release(struct lockdep_map *lock, unsigned long ip)
{
unsigned long flags;
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 468a9b8422e3..54cc5f9286e9 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -733,6 +733,9 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
*/
void __sched mutex_unlock(struct mutex *lock)
{
+#ifdef CONFIG_DEBUG_MUTEXES
+ WARN_ON(in_interrupt());
+#endif
#ifndef CONFIG_DEBUG_LOCK_ALLOC
if (__mutex_unlock_fast(lock))
return;
@@ -1091,7 +1094,7 @@ err:
err_early_kill:
spin_unlock(&lock->wait_lock);
debug_mutex_free_waiter(&waiter);
- mutex_release(&lock->dep_map, 1, ip);
+ mutex_release(&lock->dep_map, ip);
preempt_enable();
return ret;
}
@@ -1225,7 +1228,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne
DEFINE_WAKE_Q(wake_q);
unsigned long owner;
- mutex_release(&lock->dep_map, 1, ip);
+ mutex_release(&lock->dep_map, ip);
/*
* Release the lock before (potentially) taking the spinlock such that
@@ -1413,6 +1416,7 @@ int __sched mutex_trylock(struct mutex *lock)
#ifdef CONFIG_DEBUG_MUTEXES
DEBUG_LOCKS_WARN_ON(lock->magic != lock);
+ WARN_ON(in_interrupt());
#endif
locked = __mutex_trylock(lock);
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 2874bf556162..851bbb10819d 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1517,7 +1517,7 @@ int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_);
ret = rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, rt_mutex_slowlock);
if (ret)
- mutex_release(&lock->dep_map, 1, _RET_IP_);
+ mutex_release(&lock->dep_map, _RET_IP_);
return ret;
}
@@ -1561,7 +1561,7 @@ rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout)
RT_MUTEX_MIN_CHAINWALK,
rt_mutex_slowlock);
if (ret)
- mutex_release(&lock->dep_map, 1, _RET_IP_);
+ mutex_release(&lock->dep_map, _RET_IP_);
return ret;
}
@@ -1600,7 +1600,7 @@ EXPORT_SYMBOL_GPL(rt_mutex_trylock);
*/
void __sched rt_mutex_unlock(struct rt_mutex *lock)
{
- mutex_release(&lock->dep_map, 1, _RET_IP_);
+ mutex_release(&lock->dep_map, _RET_IP_);
rt_mutex_fastunlock(lock, rt_mutex_slowunlock);
}
EXPORT_SYMBOL_GPL(rt_mutex_unlock);
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index eef04551eae7..44e68761f432 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1504,7 +1504,7 @@ int __sched down_read_killable(struct rw_semaphore *sem)
rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_killable)) {
- rwsem_release(&sem->dep_map, 1, _RET_IP_);
+ rwsem_release(&sem->dep_map, _RET_IP_);
return -EINTR;
}
@@ -1546,7 +1546,7 @@ int __sched down_write_killable(struct rw_semaphore *sem)
if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock,
__down_write_killable)) {
- rwsem_release(&sem->dep_map, 1, _RET_IP_);
+ rwsem_release(&sem->dep_map, _RET_IP_);
return -EINTR;
}
@@ -1573,7 +1573,7 @@ EXPORT_SYMBOL(down_write_trylock);
*/
void up_read(struct rw_semaphore *sem)
{
- rwsem_release(&sem->dep_map, 1, _RET_IP_);
+ rwsem_release(&sem->dep_map, _RET_IP_);
__up_read(sem);
}
EXPORT_SYMBOL(up_read);
@@ -1583,7 +1583,7 @@ EXPORT_SYMBOL(up_read);
*/
void up_write(struct rw_semaphore *sem)
{
- rwsem_release(&sem->dep_map, 1, _RET_IP_);
+ rwsem_release(&sem->dep_map, _RET_IP_);
__up_write(sem);
}
EXPORT_SYMBOL(up_write);
@@ -1639,7 +1639,7 @@ int __sched down_write_killable_nested(struct rw_semaphore *sem, int subclass)
if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock,
__down_write_killable)) {
- rwsem_release(&sem->dep_map, 1, _RET_IP_);
+ rwsem_release(&sem->dep_map, _RET_IP_);
return -EINTR;
}
diff --git a/kernel/panic.c b/kernel/panic.c
index f470a038b05b..b69ee9e76cb2 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -671,17 +671,6 @@ EXPORT_SYMBOL(__stack_chk_fail);
#endif
-#ifdef CONFIG_ARCH_HAS_REFCOUNT
-void refcount_error_report(struct pt_regs *regs, const char *err)
-{
- WARN_RATELIMIT(1, "refcount_t %s at %pB in %s[%d], uid/euid: %u/%u\n",
- err, (void *)instruction_pointer(regs),
- current->comm, task_pid_nr(current),
- from_kuid_munged(&init_user_ns, current_uid()),
- from_kuid_munged(&init_user_ns, current_euid()));
-}
-#endif
-
core_param(panic, panic_timeout, int, 0644);
core_param(panic_print, panic_print, ulong, 0644);
core_param(pause_on_oops, pause_on_oops, int, 0644);
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index ca65327a6de8..c8be5a0f5259 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -248,7 +248,7 @@ static void __up_console_sem(unsigned long ip)
{
unsigned long flags;
- mutex_release(&console_lock_dep_map, 1, ip);
+ mutex_release(&console_lock_dep_map, ip);
printk_safe_enter_irqsave(flags);
up(&console_sem);
@@ -1679,20 +1679,20 @@ static int console_lock_spinning_disable_and_check(void)
raw_spin_unlock(&console_owner_lock);
if (!waiter) {
- spin_release(&console_owner_dep_map, 1, _THIS_IP_);
+ spin_release(&console_owner_dep_map, _THIS_IP_);
return 0;
}
/* The waiter is now free to continue */
WRITE_ONCE(console_waiter, false);
- spin_release(&console_owner_dep_map, 1, _THIS_IP_);
+ spin_release(&console_owner_dep_map, _THIS_IP_);
/*
* Hand off console_lock to waiter. The waiter will perform
* the up(). After this, the waiter is the console_lock owner.
*/
- mutex_release(&console_lock_dep_map, 1, _THIS_IP_);
+ mutex_release(&console_lock_dep_map, _THIS_IP_);
return 1;
}
@@ -1746,7 +1746,7 @@ static int console_trylock_spinning(void)
/* Owner will clear console_waiter on hand off */
while (READ_ONCE(console_waiter))
cpu_relax();
- spin_release(&console_owner_dep_map, 1, _THIS_IP_);
+ spin_release(&console_owner_dep_map, _THIS_IP_);
printk_safe_exit_irqrestore(flags);
/*
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d82e2f6ac41d..90e4b00ace89 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3106,7 +3106,7 @@ prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf
* do an early lockdep release here:
*/
rq_unpin_lock(rq, rf);
- spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
+ spin_release(&rq->lock.dep_map, _THIS_IP_);
#ifdef CONFIG_DEBUG_SPINLOCK
/* this is a valid case when another task releases the spinlock */
rq->lock.owner = next;