1 files changed, 277 insertions, 344 deletions

diff --git a/fs/io-wq.c b/fs/io-wq.c
index c36bbcd823ce..44e20248805a 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -13,13 +13,9 @@
 #include <linux/sched/mm.h>
 #include <linux/percpu.h>
 #include <linux/slab.h>
-#include <linux/kthread.h>
 #include <linux/rculist_nulls.h>
-#include <linux/fs_struct.h>
-#include <linux/task_work.h>
-#include <linux/blk-cgroup.h>
-#include <linux/audit.h>
 #include <linux/cpu.h>
+#include <linux/tracehook.h>
 
 #include "../kernel/sched/sched.h"
 #include "io-wq.h"
@@ -36,7 +32,6 @@ enum {
 
 enum {
 	IO_WQ_BIT_EXIT		= 0,	/* wq exiting */
-	IO_WQ_BIT_ERROR		= 1,	/* error on setup */
 };
 
 enum {
@@ -57,14 +52,12 @@ struct io_worker {
 	struct io_wq_work *cur_work;
 	spinlock_t lock;
 
-	struct rcu_head rcu;
-	struct mm_struct *mm;
-#ifdef CONFIG_BLK_CGROUP
-	struct cgroup_subsys_state *blkcg_css;
-#endif
 	const struct cred *cur_creds;
 	const struct cred *saved_creds;
-	struct nsproxy *restore_nsproxy;
+
+	struct completion ref_done;
+
+	struct rcu_head rcu;
 };
 
 #if BITS_PER_LONG == 64
@@ -93,7 +86,6 @@ struct io_wqe {
 	struct {
 		raw_spinlock_t lock;
 		struct io_wq_work_list work_list;
-		unsigned long hash_map;
 		unsigned flags;
 	} ____cacheline_aligned_in_smp;
 
@@ -103,6 +95,8 @@ struct io_wqe {
 	struct hlist_nulls_head free_list;
 	struct list_head all_list;
 
+	struct wait_queue_entry wait;
+
 	struct io_wq *wq;
 	struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
 };
@@ -119,12 +113,15 @@ struct io_wq {
 
 	struct task_struct *manager;
 	struct user_struct *user;
+
+	struct io_wq_hash *hash;
+
 	refcount_t refs;
 	struct completion done;
 
 	struct hlist_node cpuhp_node;
 
-	refcount_t use_refs;
+	pid_t task_pid;
 };
 
 static enum cpuhp_state io_wq_online;
@@ -137,62 +134,7 @@ static bool io_worker_get(struct io_worker *worker)
 static void io_worker_release(struct io_worker *worker)
 {
 	if (refcount_dec_and_test(&worker->ref))
-		wake_up_process(worker->task);
-}
-
-/*
- * Note: drops the wqe->lock if returning true! The caller must re-acquire
- * the lock in that case. Some callers need to restart handling if this
- * happens, so we can't just re-acquire the lock on behalf of the caller.
- */
-static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker)
-{
-	bool dropped_lock = false;
-
-	if (worker->saved_creds) {
-		revert_creds(worker->saved_creds);
-		worker->cur_creds = worker->saved_creds = NULL;
-	}
-
-	if (current->files) {
-		__acquire(&wqe->lock);
-		raw_spin_unlock_irq(&wqe->lock);
-		dropped_lock = true;
-
-		task_lock(current);
-		current->files = NULL;
-		current->nsproxy = worker->restore_nsproxy;
-		task_unlock(current);
-	}
-
-	if (current->fs)
-		current->fs = NULL;
-
-	/*
-	 * If we have an active mm, we need to drop the wq lock before unusing
-	 * it. If we do, return true and let the caller retry the idle loop.
-	 */
-	if (worker->mm) {
-		if (!dropped_lock) {
-			__acquire(&wqe->lock);
-			raw_spin_unlock_irq(&wqe->lock);
-			dropped_lock = true;
-		}
-		__set_current_state(TASK_RUNNING);
-		kthread_unuse_mm(worker->mm);
-		mmput(worker->mm);
-		worker->mm = NULL;
-	}
-
-#ifdef CONFIG_BLK_CGROUP
-	if (worker->blkcg_css) {
-		kthread_associate_blkcg(NULL);
-		worker->blkcg_css = NULL;
-	}
-#endif
-	if (current->signal->rlim[RLIMIT_FSIZE].rlim_cur != RLIM_INFINITY)
-		current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
-	return dropped_lock;
+		complete(&worker->ref_done);
 }
 
 static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe,
@@ -204,9 +146,10 @@ static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe,
 	return &wqe->acct[IO_WQ_ACCT_BOUND];
 }
 
-static inline struct io_wqe_acct *io_wqe_get_acct(struct io_wqe *wqe,
-						  struct io_worker *worker)
+static inline struct io_wqe_acct *io_wqe_get_acct(struct io_worker *worker)
 {
+	struct io_wqe *wqe = worker->wqe;
+
 	if (worker->flags & IO_WORKER_F_BOUND)
 		return &wqe->acct[IO_WQ_ACCT_BOUND];
 
@@ -216,39 +159,36 @@ static inline struct io_wqe_acct *io_wqe_get_acct(struct io_wqe *wqe,
 static void io_worker_exit(struct io_worker *worker)
 {
 	struct io_wqe *wqe = worker->wqe;
-	struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+	unsigned flags;
 
-	/*
-	 * If we're not at zero, someone else is holding a brief reference
-	 * to the worker. Wait for that to go away.
-	 */
-	set_current_state(TASK_INTERRUPTIBLE);
-	if (!refcount_dec_and_test(&worker->ref))
-		schedule();
-	__set_current_state(TASK_RUNNING);
+	if (refcount_dec_and_test(&worker->ref))
+		complete(&worker->ref_done);
+	wait_for_completion(&worker->ref_done);
 
 	preempt_disable();
 	current->flags &= ~PF_IO_WORKER;
-	if (worker->flags & IO_WORKER_F_RUNNING)
+	flags = worker->flags;
+	worker->flags = 0;
+	if (flags & IO_WORKER_F_RUNNING)
 		atomic_dec(&acct->nr_running);
-	if (!(worker->flags & IO_WORKER_F_BOUND))
-		atomic_dec(&wqe->wq->user->processes);
 	worker->flags = 0;
 	preempt_enable();
 
+	if (worker->saved_creds) {
+		revert_creds(worker->saved_creds);
+		worker->cur_creds = worker->saved_creds = NULL;
+	}
+
 	raw_spin_lock_irq(&wqe->lock);
-	hlist_nulls_del_rcu(&worker->nulls_node);
+	if (flags & IO_WORKER_F_FREE)
+		hlist_nulls_del_rcu(&worker->nulls_node);
 	list_del_rcu(&worker->all_list);
-	if (__io_worker_unuse(wqe, worker)) {
-		__release(&wqe->lock);
-		raw_spin_lock_irq(&wqe->lock);
-	}
 	acct->nr_workers--;
 	raw_spin_unlock_irq(&wqe->lock);
 
 	kfree_rcu(worker, rcu);
-	if (refcount_dec_and_test(&wqe->wq->refs))
-		complete(&wqe->wq->done);
+	io_wq_put(wqe->wq);
 }
 
 static inline bool io_wqe_run_queue(struct io_wqe *wqe)
@@ -306,33 +246,27 @@ static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
 		wake_up_process(wqe->wq->manager);
 }
 
-static void io_wqe_inc_running(struct io_wqe *wqe, struct io_worker *worker)
+static void io_wqe_inc_running(struct io_worker *worker)
 {
-	struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
 
 	atomic_inc(&acct->nr_running);
 }
 
-static void io_wqe_dec_running(struct io_wqe *wqe, struct io_worker *worker)
+static void io_wqe_dec_running(struct io_worker *worker)
 	__must_hold(wqe->lock)
 {
-	struct io_wqe_acct *acct = io_wqe_get_acct(wqe, worker);
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+	struct io_wqe *wqe = worker->wqe;
 
 	if (atomic_dec_and_test(&acct->nr_running) && io_wqe_run_queue(wqe))
 		io_wqe_wake_worker(wqe, acct);
 }
 
-static void io_worker_start(struct io_wqe *wqe, struct io_worker *worker)
+static void io_worker_start(struct io_worker *worker)
 {
-	allow_kernel_signal(SIGINT);
-
-	current->flags |= PF_IO_WORKER;
-	current->fs = NULL;
-	current->files = NULL;
-
 	worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
-	worker->restore_nsproxy = current->nsproxy;
-	io_wqe_inc_running(wqe, worker);
+	io_wqe_inc_running(worker);
 }
 
 /*
@@ -357,19 +291,17 @@ static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker,
 	worker_bound = (worker->flags & IO_WORKER_F_BOUND) != 0;
 	work_bound = (work->flags & IO_WQ_WORK_UNBOUND) == 0;
 	if (worker_bound != work_bound) {
-		io_wqe_dec_running(wqe, worker);
+		io_wqe_dec_running(worker);
 		if (work_bound) {
 			worker->flags |= IO_WORKER_F_BOUND;
 			wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers--;
 			wqe->acct[IO_WQ_ACCT_BOUND].nr_workers++;
-			atomic_dec(&wqe->wq->user->processes);
 		} else {
 			worker->flags &= ~IO_WORKER_F_BOUND;
 			wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers++;
 			wqe->acct[IO_WQ_ACCT_BOUND].nr_workers--;
-			atomic_inc(&wqe->wq->user->processes);
 		}
-		io_wqe_inc_running(wqe, worker);
+		io_wqe_inc_running(worker);
 	 }
 }
 
@@ -380,15 +312,17 @@ static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker,
  * retry the loop in that case (we changed task state), we don't regrab
  * the lock if we return success.
  */
-static bool __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
+static void __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
 	__must_hold(wqe->lock)
 {
 	if (!(worker->flags & IO_WORKER_F_FREE)) {
 		worker->flags |= IO_WORKER_F_FREE;
 		hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
 	}
-
-	return __io_worker_unuse(wqe, worker);
+	if (worker->saved_creds) {
+		revert_creds(worker->saved_creds);
+		worker->cur_creds = worker->saved_creds = NULL;
+	}
 }
 
 static inline unsigned int io_get_work_hash(struct io_wq_work *work)
@@ -396,14 +330,31 @@ static inline unsigned int io_get_work_hash(struct io_wq_work *work)
 	return work->flags >> IO_WQ_HASH_SHIFT;
 }
 
+static void io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
+{
+	struct io_wq *wq = wqe->wq;
+
+	spin_lock(&wq->hash->wait.lock);
+	if (list_empty(&wqe->wait.entry)) {
+		__add_wait_queue(&wq->hash->wait, &wqe->wait);
+		if (!test_bit(hash, &wq->hash->map)) {
+			__set_current_state(TASK_RUNNING);
+			list_del_init(&wqe->wait.entry);
+		}
+	}
+	spin_unlock(&wq->hash->wait.lock);
+}
+
 static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
 	__must_hold(wqe->lock)
 {
 	struct io_wq_work_node *node, *prev;
 	struct io_wq_work *work, *tail;
-	unsigned int hash;
+	unsigned int stall_hash = -1U;
 
 	wq_list_for_each(node, prev, &wqe->work_list) {
+		unsigned int hash;
+
 		work = container_of(node, struct io_wq_work, list);
 
 		/* not hashed, can run anytime */
@@ -412,111 +363,60 @@ static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
 			return work;
 		}
 
-		/* hashed, can run if not already running */
 		hash = io_get_work_hash(work);
-		if (!(wqe->hash_map & BIT(hash))) {
-			wqe->hash_map |= BIT(hash);
-			/* all items with this hash lie in [work, tail] */
-			tail = wqe->hash_tail[hash];
+		/* all items with this hash lie in [work, tail] */
+		tail = wqe->hash_tail[hash];
+
+		/* hashed, can run if not already running */
+		if (!test_and_set_bit(hash, &wqe->wq->hash->map)) {
 			wqe->hash_tail[hash] = NULL;
 			wq_list_cut(&wqe->work_list, &tail->list, prev);
 			return work;
 		}
+		if (stall_hash == -1U)
+			stall_hash = hash;
+		/* fast forward to a next hash, for-each will fix up @prev */
+		node = &tail->list;
 	}
 
-	return NULL;
-}
-
-static void io_wq_switch_mm(struct io_worker *worker, struct io_wq_work *work)
-{
-	if (worker->mm) {
-		kthread_unuse_mm(worker->mm);
-		mmput(worker->mm);
-		worker->mm = NULL;
+	if (stall_hash != -1U) {
+		raw_spin_unlock(&wqe->lock);
+		io_wait_on_hash(wqe, stall_hash);
+		raw_spin_lock(&wqe->lock);
 	}
 
-	if (mmget_not_zero(work->identity->mm)) {
-		kthread_use_mm(work->identity->mm);
-		worker->mm = work->identity->mm;
-		return;
-	}
-
-	/* failed grabbing mm, ensure work gets cancelled */
-	work->flags |= IO_WQ_WORK_CANCEL;
+	return NULL;
 }
 
-static inline void io_wq_switch_blkcg(struct io_worker *worker,
-				      struct io_wq_work *work)
+static void io_flush_signals(void)
 {
-#ifdef CONFIG_BLK_CGROUP
-	if (!(work->flags & IO_WQ_WORK_BLKCG))
-		return;
-	if (work->identity->blkcg_css != worker->blkcg_css) {
-		kthread_associate_blkcg(work->identity->blkcg_css);
-		worker->blkcg_css = work->identity->blkcg_css;
+	if (unlikely(test_tsk_thread_flag(current, TIF_NOTIFY_SIGNAL))) {
+		if (current->task_works)
+			task_work_run();
+		clear_tsk_thread_flag(current, TIF_NOTIFY_SIGNAL);
 	}
-#endif
 }
 
 static void io_wq_switch_creds(struct io_worker *worker,
 			       struct io_wq_work *work)
 {
-	const struct cred *old_creds = override_creds(work->identity->creds);
+	const struct cred *old_creds = override_creds(work->creds);
 
-	worker->cur_creds = work->identity->creds;
+	worker->cur_creds = work->creds;
 	if (worker->saved_creds)
 		put_cred(old_creds); /* creds set by previous switch */
 	else
 		worker->saved_creds = old_creds;
 }
 
-static void io_impersonate_work(struct io_worker *worker,
-				struct io_wq_work *work)
-{
-	if ((work->flags & IO_WQ_WORK_FILES) &&
-	    current->files != work->identity->files) {
-		task_lock(current);
-		current->files = work->identity->files;
-		current->nsproxy = work->identity->nsproxy;
-		task_unlock(current);
-		if (!work->identity->files) {
-			/* failed grabbing files, ensure work gets cancelled */
-			work->flags |= IO_WQ_WORK_CANCEL;
-		}
-	}
-	if ((work->flags & IO_WQ_WORK_FS) && current->fs != work->identity->fs)
-		current->fs = work->identity->fs;
-	if ((work->flags & IO_WQ_WORK_MM) && work->identity->mm != worker->mm)
-		io_wq_switch_mm(worker, work);
-	if ((work->flags & IO_WQ_WORK_CREDS) &&
-	    worker->cur_creds != work->identity->creds)
-		io_wq_switch_creds(worker, work);
-	if (work->flags & IO_WQ_WORK_FSIZE)
-		current->signal->rlim[RLIMIT_FSIZE].rlim_cur = work->identity->fsize;
-	else if (current->signal->rlim[RLIMIT_FSIZE].rlim_cur != RLIM_INFINITY)
-		current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
-	io_wq_switch_blkcg(worker, work);
-#ifdef CONFIG_AUDIT
-	current->loginuid = work->identity->loginuid;
-	current->sessionid = work->identity->sessionid;
-#endif
-}
-
 static void io_assign_current_work(struct io_worker *worker,
 				   struct io_wq_work *work)
 {
 	if (work) {
-		/* flush pending signals before assigning new work */
-		if (signal_pending(current))
-			flush_signals(current);
+		io_flush_signals();
 		cond_resched();
 	}
 
-#ifdef CONFIG_AUDIT
-	current->loginuid = KUIDT_INIT(AUDIT_UID_UNSET);
-	current->sessionid = AUDIT_SID_UNSET;
-#endif
-
 	spin_lock_irq(&worker->lock);
 	worker->cur_work = work;
 	spin_unlock_irq(&worker->lock);
@@ -550,6 +450,7 @@ get_next:
 		if (!work)
 			break;
 		io_assign_current_work(worker, work);
+		__set_current_state(TASK_RUNNING);
 
 		/* handle a whole dependent link */
 		do {
@@ -557,7 +458,8 @@ get_next:
 			unsigned int hash = io_get_work_hash(work);
 
 			next_hashed = wq_next_work(work);
-			io_impersonate_work(worker, work);
+			if (work->creds && worker->cur_creds != work->creds)
+				io_wq_switch_creds(worker, work);
 			wq->do_work(work);
 			io_assign_current_work(worker, NULL);
 
@@ -572,8 +474,10 @@ get_next:
 				io_wqe_enqueue(wqe, linked);
 
 			if (hash != -1U && !next_hashed) {
+				clear_bit(hash, &wq->hash->map);
+				if (wq_has_sleeper(&wq->hash->wait))
+					wake_up(&wq->hash->wait);
 				raw_spin_lock_irq(&wqe->lock);
-				wqe->hash_map &= ~BIT_ULL(hash);
 				wqe->flags &= ~IO_WQE_FLAG_STALLED;
 				/* skip unnecessary unlock-lock wqe->lock */
 				if (!work)
@@ -592,27 +496,23 @@ static int io_wqe_worker(void *data)
 	struct io_wqe *wqe = worker->wqe;
 	struct io_wq *wq = wqe->wq;
 
-	io_worker_start(wqe, worker);
+	io_worker_start(worker);
 
 	while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
 		set_current_state(TASK_INTERRUPTIBLE);
 loop:
 		raw_spin_lock_irq(&wqe->lock);
 		if (io_wqe_run_queue(wqe)) {
-			__set_current_state(TASK_RUNNING);
 			io_worker_handle_work(worker);
 			goto loop;
 		}
-		/* drops the lock on success, retry */
-		if (__io_worker_idle(wqe, worker)) {
-			__release(&wqe->lock);
-			goto loop;
-		}
+		__io_worker_idle(wqe, worker);
 		raw_spin_unlock_irq(&wqe->lock);
-		if (signal_pending(current))
-			flush_signals(current);
+		io_flush_signals();
 		if (schedule_timeout(WORKER_IDLE_TIMEOUT))
 			continue;
+		if (fatal_signal_pending(current))
+			break;
 		/* timed out, exit unless we're the fixed worker */
 		if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
 		    !(worker->flags & IO_WORKER_F_FIXED))
@@ -636,15 +536,16 @@ loop:
  */
 void io_wq_worker_running(struct task_struct *tsk)
 {
-	struct io_worker *worker = kthread_data(tsk);
-	struct io_wqe *wqe = worker->wqe;
+	struct io_worker *worker = tsk->pf_io_worker;
 
+	if (!worker)
+		return;
 	if (!(worker->flags & IO_WORKER_F_UP))
 		return;
 	if (worker->flags & IO_WORKER_F_RUNNING)
 		return;
 	worker->flags |= IO_WORKER_F_RUNNING;
-	io_wqe_inc_running(wqe, worker);
+	io_wqe_inc_running(worker);
 }
 
 /*
@@ -654,9 +555,10 @@ void io_wq_worker_running(struct task_struct *tsk)
  */
 void io_wq_worker_sleeping(struct task_struct *tsk)
 {
-	struct io_worker *worker = kthread_data(tsk);
-	struct io_wqe *wqe = worker->wqe;
+	struct io_worker *worker = tsk->pf_io_worker;
 
+	if (!worker)
+		return;
 	if (!(worker->flags & IO_WORKER_F_UP))
 		return;
 	if (!(worker->flags & IO_WORKER_F_RUNNING))
@@ -664,32 +566,27 @@ void io_wq_worker_sleeping(struct task_struct *tsk)
 
 	worker->flags &= ~IO_WORKER_F_RUNNING;
 
-	raw_spin_lock_irq(&wqe->lock);
-	io_wqe_dec_running(wqe, worker);
-	raw_spin_unlock_irq(&wqe->lock);
+	raw_spin_lock_irq(&worker->wqe->lock);
+	io_wqe_dec_running(worker);
+	raw_spin_unlock_irq(&worker->wqe->lock);
 }
 
-static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
+static int task_thread(void *data, int index)
 {
+	struct io_worker *worker = data;
+	struct io_wqe *wqe = worker->wqe;
 	struct io_wqe_acct *acct = &wqe->acct[index];
-	struct io_worker *worker;
+	struct io_wq *wq = wqe->wq;
+	char buf[TASK_COMM_LEN];
 
-	worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node);
-	if (!worker)
-		return false;
+	sprintf(buf, "iou-wrk-%d", wq->task_pid);
+	set_task_comm(current, buf);
 
-	refcount_set(&worker->ref, 1);
-	worker->nulls_node.pprev = NULL;
-	worker->wqe = wqe;
-	spin_lock_init(&worker->lock);
+	current->pf_io_worker = worker;
+	worker->task = current;
 
-	worker->task = kthread_create_on_node(io_wqe_worker, worker, wqe->node,
-				"io_wqe_worker-%d/%d", index, wqe->node);
-	if (IS_ERR(worker->task)) {
-		kfree(worker);
-		return false;
-	}
-	kthread_bind_mask(worker->task, cpumask_of_node(wqe->node));
+	set_cpus_allowed_ptr(current, cpumask_of_node(wqe->node));
+	current->flags |= PF_NO_SETAFFINITY;
 
 	raw_spin_lock_irq(&wqe->lock);
 	hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
@@ -702,11 +599,63 @@ static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
 	acct->nr_workers++;
 	raw_spin_unlock_irq(&wqe->lock);
 
-	if (index == IO_WQ_ACCT_UNBOUND)
-		atomic_inc(&wq->user->processes);
+	io_wqe_worker(data);
+	do_exit(0);
+}
+
+static int task_thread_bound(void *data)
+{
+	return task_thread(data, IO_WQ_ACCT_BOUND);
+}
+
+static int task_thread_unbound(void *data)
+{
+	return task_thread(data, IO_WQ_ACCT_UNBOUND);
+}
+
+pid_t io_wq_fork_thread(int (*fn)(void *), void *arg)
+{
+	unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
+				CLONE_IO|SIGCHLD;
+	struct kernel_clone_args args = {
+		.flags		= ((lower_32_bits(flags) | CLONE_VM |
+				    CLONE_UNTRACED) & ~CSIGNAL),
+		.exit_signal	= (lower_32_bits(flags) & CSIGNAL),
+		.stack		= (unsigned long)fn,
+		.stack_size	= (unsigned long)arg,
+	};
+
+	return kernel_clone(&args);
+}
+
+static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
+{
+	struct io_worker *worker;
+	pid_t pid;
+
+	__set_current_state(TASK_RUNNING);
+
+	worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node);
+	if (!worker)
+		return false;
+
+	refcount_set(&worker->ref, 1);
+	worker->nulls_node.pprev = NULL;
+	worker->wqe = wqe;
+	spin_lock_init(&worker->lock);
+	init_completion(&worker->ref_done);
 
 	refcount_inc(&wq->refs);
-	wake_up_process(worker->task);
+
+	if (index == IO_WQ_ACCT_BOUND)
+		pid = io_wq_fork_thread(task_thread_bound, worker);
+	else
+		pid = io_wq_fork_thread(task_thread_unbound, worker);
+	if (pid < 0) {
+		io_wq_put(wq);
+		kfree(worker);
+		return false;
+	}
 	return true;
 }
 
@@ -752,93 +701,57 @@ static bool io_wq_worker_wake(struct io_worker *worker, void *data)
 	return false;
 }
 
-/*
- * Manager thread. Tasked with creating new workers, if we need them.
- */
-static int io_wq_manager(void *data)
+static void io_wq_check_workers(struct io_wq *wq)
 {
-	struct io_wq *wq = data;
 	int node;
 
-	/* create fixed workers */
-	refcount_set(&wq->refs, 1);
 	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
+		bool fork_worker[2] = { false, false };
+
 		if (!node_online(node))
 			continue;
-		if (create_io_worker(wq, wq->wqes[node], IO_WQ_ACCT_BOUND))
-			continue;
-		set_bit(IO_WQ_BIT_ERROR, &wq->state);
-		set_bit(IO_WQ_BIT_EXIT, &wq->state);
-		goto out;
-	}
-
-	complete(&wq->done);
-
-	while (!kthread_should_stop()) {
-		if (current->task_works)
-			task_work_run();
-
-		for_each_node(node) {
-			struct io_wqe *wqe = wq->wqes[node];
-			bool fork_worker[2] = { false, false };
-
-			if (!node_online(node))
-				continue;
-
-			raw_spin_lock_irq(&wqe->lock);
-			if (io_wqe_need_worker(wqe, IO_WQ_ACCT_BOUND))
-				fork_worker[IO_WQ_ACCT_BOUND] = true;
-			if (io_wqe_need_worker(wqe, IO_WQ_ACCT_UNBOUND))
-				fork_worker[IO_WQ_ACCT_UNBOUND] = true;
-			raw_spin_unlock_irq(&wqe->lock);
-			if (fork_worker[IO_WQ_ACCT_BOUND])
-				create_io_worker(wq, wqe, IO_WQ_ACCT_BOUND);
-			if (fork_worker[IO_WQ_ACCT_UNBOUND])
-				create_io_worker(wq, wqe, IO_WQ_ACCT_UNBOUND);
-		}
-		set_current_state(TASK_INTERRUPTIBLE);
-		schedule_timeout(HZ);
-	}
-
-	if (current->task_works)
-		task_work_run();
 
-out:
-	if (refcount_dec_and_test(&wq->refs)) {
-		complete(&wq->done);
-		return 0;
-	}
-	/* if ERROR is set and we get here, we have workers to wake */
-	if (test_bit(IO_WQ_BIT_ERROR, &wq->state)) {
-		rcu_read_lock();
-		for_each_node(node)
-			io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL);
-		rcu_read_unlock();
+		raw_spin_lock_irq(&wqe->lock);
+		if (io_wqe_need_worker(wqe, IO_WQ_ACCT_BOUND))
+			fork_worker[IO_WQ_ACCT_BOUND] = true;
+		if (io_wqe_need_worker(wqe, IO_WQ_ACCT_UNBOUND))
+			fork_worker[IO_WQ_ACCT_UNBOUND] = true;
+		raw_spin_unlock_irq(&wqe->lock);
+		if (fork_worker[IO_WQ_ACCT_BOUND])
+			create_io_worker(wq, wqe, IO_WQ_ACCT_BOUND);
+		if (fork_worker[IO_WQ_ACCT_UNBOUND])
+			create_io_worker(wq, wqe, IO_WQ_ACCT_UNBOUND);
 	}
-	return 0;
 }
 
-static bool io_wq_can_queue(struct io_wqe *wqe, struct io_wqe_acct *acct,
-			    struct io_wq_work *work)
+/*
+ * Manager thread. Tasked with creating new workers, if we need them.
+ */
+static int io_wq_manager(void *data)
 {
-	bool free_worker;
-
-	if (!(work->flags & IO_WQ_WORK_UNBOUND))
-		return true;
-	if (atomic_read(&acct->nr_running))
-		return true;
+	struct io_wq *wq = data;
+	char buf[TASK_COMM_LEN];
 
-	rcu_read_lock();
-	free_worker = !hlist_nulls_empty(&wqe->free_list);
-	rcu_read_unlock();
-	if (free_worker)
-		return true;
+	sprintf(buf, "iou-mgr-%d", wq->task_pid);
+	set_task_comm(current, buf);
+	current->flags |= PF_IO_WORKER;
+	wq->manager = current;
 
-	if (atomic_read(&wqe->wq->user->processes) >= acct->max_workers &&
-	    !(capable(CAP_SYS_RESOURCE) || capable(CAP_SYS_ADMIN)))
-		return false;
+	complete(&wq->done);
 
-	return true;
+	do {
+		set_current_state(TASK_INTERRUPTIBLE);
+		io_wq_check_workers(wq);
+		schedule_timeout(HZ);
+		if (fatal_signal_pending(current))
+			set_bit(IO_WQ_BIT_EXIT, &wq->state);
+	} while (!test_bit(IO_WQ_BIT_EXIT, &wq->state));
+
+	io_wq_check_workers(wq);
+	wq->manager = NULL;
+	io_wq_put(wq);
+	do_exit(0);
 }
 
 static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
@@ -872,20 +785,37 @@ append:
 	wq_list_add_after(&work->list, &tail->list, &wqe->work_list);
 }
 
+static int io_wq_fork_manager(struct io_wq *wq)
+{
+	int ret;
+
+	if (wq->manager)
+		return 0;
+
+	clear_bit(IO_WQ_BIT_EXIT, &wq->state);
+	refcount_inc(&wq->refs);
+	current->flags |= PF_IO_WORKER;
+	ret = io_wq_fork_thread(io_wq_manager, wq);
+	current->flags &= ~PF_IO_WORKER;
+	if (ret >= 0) {
+		wait_for_completion(&wq->done);
+		return 0;
+	}
+
+	io_wq_put(wq);
+	return ret;
+}
+
 static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
 {
 	struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
 	int work_flags;
 	unsigned long flags;
 
-	/*
-	 * Do early check to see if we need a new unbound worker, and if we do,
-	 * if we're allowed to do so. This isn't 100% accurate as there's a
-	 * gap between this check and incrementing the value, but that's OK.
-	 * It's close enough to not be an issue, fork() has the same delay.
-	 */
-	if (unlikely(!io_wq_can_queue(wqe, acct, work))) {
-		io_run_cancel(work, wqe);
+	/* Can only happen if manager creation fails after exec */
+	if (unlikely(io_wq_fork_manager(wqe->wq))) {
+		work->flags |= IO_WQ_WORK_CANCEL;
+		wqe->wq->do_work(work);
 		return;
 	}
 
@@ -939,7 +869,7 @@ static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
 	spin_lock_irqsave(&worker->lock, flags);
 	if (worker->cur_work &&
 	    match->fn(worker->cur_work, match->data)) {
-		send_sig(SIGINT, worker->task, 1);
+		set_notify_signal(worker->task);
 		match->nr_running++;
 	}
 	spin_unlock_irqrestore(&worker->lock, flags);
@@ -1043,6 +973,24 @@ enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
 	return IO_WQ_CANCEL_NOTFOUND;
 }
 
+static int io_wqe_hash_wake(struct wait_queue_entry *wait, unsigned mode,
+			    int sync, void *key)
+{
+	struct io_wqe *wqe = container_of(wait, struct io_wqe, wait);
+	int ret;
+
+	list_del_init(&wait->entry);
+
+	rcu_read_lock();
+	ret = io_wqe_activate_free_worker(wqe);
+	rcu_read_unlock();
+
+	if (!ret)
+		wake_up_process(wqe->wq->manager);
+
+	return 1;
+}
+
 struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 {
 	int ret = -ENOMEM, node;
@@ -1063,12 +1011,11 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 	if (ret)
 		goto err_wqes;
 
+	refcount_inc(&data->hash->refs);
+	wq->hash = data->hash;
 	wq->free_work = data->free_work;
 	wq->do_work = data->do_work;
 
-	/* caller must already hold a reference to this */
-	wq->user = data->user;
-
 	ret = -ENOMEM;
 	for_each_node(node) {
 		struct io_wqe *wqe;
@@ -1083,11 +1030,11 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 		wqe->node = alloc_node;
 		wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
 		atomic_set(&wqe->acct[IO_WQ_ACCT_BOUND].nr_running, 0);
-		if (wq->user) {
-			wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
+		wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
 					task_rlimit(current, RLIMIT_NPROC);
-		}
 		atomic_set(&wqe->acct[IO_WQ_ACCT_UNBOUND].nr_running, 0);
+		wqe->wait.func = io_wqe_hash_wake;
+		INIT_LIST_HEAD(&wqe->wait.entry);
 		wqe->wq = wq;
 		raw_spin_lock_init(&wqe->lock);
 		INIT_WQ_LIST(&wqe->work_list);
@@ -1095,23 +1042,16 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
 		INIT_LIST_HEAD(&wqe->all_list);
 	}
 
+	wq->task_pid = current->pid;
 	init_completion(&wq->done);
+	refcount_set(&wq->refs, 1);
 
-	wq->manager = kthread_create(io_wq_manager, wq, "io_wq_manager");
-	if (!IS_ERR(wq->manager)) {
-		wake_up_process(wq->manager);
-		wait_for_completion(&wq->done);
-		if (test_bit(IO_WQ_BIT_ERROR, &wq->state)) {
-			ret = -ENOMEM;
-			goto err;
-		}
-		refcount_set(&wq->use_refs, 1);
-		reinit_completion(&wq->done);
+	ret = io_wq_fork_manager(wq);
+	if (!ret)
 		return wq;
-	}
 
-	ret = PTR_ERR(wq->manager);
-	complete(&wq->done);
+	io_wq_put(wq);
+	io_wq_put_hash(data->hash);
 err:
 	cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
 	for_each_node(node)
@@ -1123,15 +1063,7 @@ err_wq:
 	return ERR_PTR(ret);
 }
 
-bool io_wq_get(struct io_wq *wq, struct io_wq_data *data)
-{
-	if (data->free_work != wq->free_work || data->do_work != wq->do_work)
-		return false;
-
-	return refcount_inc_not_zero(&wq->use_refs);
-}
-
-static void __io_wq_destroy(struct io_wq *wq)
+static void io_wq_destroy(struct io_wq *wq)
 {
 	int node;
 
@@ -1139,30 +1071,31 @@ static void __io_wq_destroy(struct io_wq *wq)
 
 	set_bit(IO_WQ_BIT_EXIT, &wq->state);
 	if (wq->manager)
-		kthread_stop(wq->manager);
+		wake_up_process(wq->manager);
 
 	rcu_read_lock();
 	for_each_node(node)
 		io_wq_for_each_worker(wq->wqes[node], io_wq_worker_wake, NULL);
 	rcu_read_unlock();
 
-	wait_for_completion(&wq->done);
+	spin_lock_irq(&wq->hash->wait.lock);
+	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
 
-	for_each_node(node)
-		kfree(wq->wqes[node]);
+		list_del_init(&wqe->wait.entry);
+		kfree(wqe);
+	}
+	spin_unlock_irq(&wq->hash->wait.lock);
+	io_wq_put_hash(wq->hash);
 	kfree(wq->wqes);
 	kfree(wq);
-}
 
-void io_wq_destroy(struct io_wq *wq)
-{
-	if (refcount_dec_and_test(&wq->use_refs))
-		__io_wq_destroy(wq);
 }
 
-struct task_struct *io_wq_get_task(struct io_wq *wq)
+void io_wq_put(struct io_wq *wq)
 {
-	return wq->manager;
+	if (refcount_dec_and_test(&wq->refs))
+		io_wq_destroy(wq);
 }
 
 static bool io_wq_worker_affinity(struct io_worker *worker, void *data)