Merge tag 'io_uring-5.11-2020-12-23' of git://git.kernel.dk/linux-block

Pull io_uring fixes from Jens Axboe:
 "All straight fixes, or a prep patch for a fix, either bound for stable
  or fixing issues from this merge window. In particular:

   - Fix new shutdown op not breaking links on failure

   - Hold mm->mmap_sem for mm->locked_vm manipulation

   - Various cancelation fixes (me, Pavel)

   - Fix error path potential double ctx free (Pavel)

   - IOPOLL fixes (Xiaoguang)"

* tag 'io_uring-5.11-2020-12-23' of git://git.kernel.dk/linux-block:
  io_uring: hold uring_lock while completing failed polled io in io_wq_submit_work()
  io_uring: fix double io_uring free
  io_uring: fix ignoring xa_store errors
  io_uring: end waiting before task cancel attempts
  io_uring: always progress task_work on task cancel
  io-wq: kill now unused io_wq_cancel_all()
  io_uring: make ctx cancel on exit targeted to actual ctx
  io_uring: fix 0-iov read buffer select
  io_uring: close a small race gap for files cancel
  io_uring: fix io_wqe->work_list corruption
  io_uring: limit {io|sq}poll submit locking scope
  io_uring: inline io_cqring_mark_overflow()
  io_uring: consolidate CQ nr events calculation
  io_uring: remove racy overflow list fast checks
  io_uring: cancel reqs shouldn't kill overflow list
  io_uring: hold mmap_sem for mm->locked_vm manipulation
  io_uring: break links on shutdown failure

3 files changed, 120 insertions, 123 deletions

diff --git a/fs/io-wq.c b/fs/io-wq.c
index f72d53848dcb..a564f36e260c 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -36,8 +36,7 @@ enum {
 
 enum {
 	IO_WQ_BIT_EXIT		= 0,	/* wq exiting */
-	IO_WQ_BIT_CANCEL	= 1,	/* cancel work on list */
-	IO_WQ_BIT_ERROR		= 2,	/* error on setup */
+	IO_WQ_BIT_ERROR		= 1,	/* error on setup */
 };
 
 enum {
@@ -561,12 +560,6 @@ get_next:
 
 			next_hashed = wq_next_work(work);
 			io_impersonate_work(worker, work);
-			/*
-			 * OK to set IO_WQ_WORK_CANCEL even for uncancellable
-			 * work, the worker function will do the right thing.
-			 */
-			if (test_bit(IO_WQ_BIT_CANCEL, &wq->state))
-				work->flags |= IO_WQ_WORK_CANCEL;
 
 			old_work = work;
 			linked = wq->do_work(work);
@@ -732,12 +725,6 @@ static inline bool io_wqe_need_worker(struct io_wqe *wqe, int index)
 	return acct->nr_workers < acct->max_workers;
 }
 
-static bool io_wqe_worker_send_sig(struct io_worker *worker, void *data)
-{
-	send_sig(SIGINT, worker->task, 1);
-	return false;
-}
-
 /*
  * Iterate the passed in list and call the specific function for each
  * worker that isn't exiting
@@ -938,21 +925,6 @@ void io_wq_hash_work(struct io_wq_work *work, void *val)
 	work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
 }
 
-void io_wq_cancel_all(struct io_wq *wq)
-{
-	int node;
-
-	set_bit(IO_WQ_BIT_CANCEL, &wq->state);
-
-	rcu_read_lock();
-	for_each_node(node) {
-		struct io_wqe *wqe = wq->wqes[node];
-
-		io_wq_for_each_worker(wqe, io_wqe_worker_send_sig, NULL);
-	}
-	rcu_read_unlock();
-}
-
 struct io_cb_cancel_data {
 	work_cancel_fn *fn;
 	void *data;
diff --git a/fs/io-wq.h b/fs/io-wq.h
index 069496c6d4f9..b158f8addcf3 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -59,6 +59,7 @@ static inline void wq_list_add_tail(struct io_wq_work_node *node,
 		list->last->next = node;
 		list->last = node;
 	}
+	node->next = NULL;
 }
 
 static inline void wq_list_cut(struct io_wq_work_list *list,
@@ -128,8 +129,6 @@ static inline bool io_wq_is_hashed(struct io_wq_work *work)
 	return work->flags & IO_WQ_WORK_HASHED;
 }
 
-void io_wq_cancel_all(struct io_wq *wq);
-
 typedef bool (work_cancel_fn)(struct io_wq_work *, void *);
 
 enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6f9392c35eef..7e35283fc0b1 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1693,6 +1693,11 @@ static inline bool io_should_trigger_evfd(struct io_ring_ctx *ctx)
 	return io_wq_current_is_worker();
 }
 
+static inline unsigned __io_cqring_events(struct io_ring_ctx *ctx)
+{
+	return ctx->cached_cq_tail - READ_ONCE(ctx->rings->cq.head);
+}
+
 static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
 {
 	if (waitqueue_active(&ctx->wait))
@@ -1703,15 +1708,6 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
 		eventfd_signal(ctx->cq_ev_fd, 1);
 }
 
-static void io_cqring_mark_overflow(struct io_ring_ctx *ctx)
-{
-	if (list_empty(&ctx->cq_overflow_list)) {
-		clear_bit(0, &ctx->sq_check_overflow);
-		clear_bit(0, &ctx->cq_check_overflow);
-		ctx->rings->sq_flags &= ~IORING_SQ_CQ_OVERFLOW;
-	}
-}
-
 /* Returns true if there are no backlogged entries after the flush */
 static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
 				     struct task_struct *tsk,
@@ -1721,23 +1717,13 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
 	struct io_kiocb *req, *tmp;
 	struct io_uring_cqe *cqe;
 	unsigned long flags;
+	bool all_flushed;
 	LIST_HEAD(list);
 
-	if (!force) {
-		if (list_empty_careful(&ctx->cq_overflow_list))
-			return true;
-		if ((ctx->cached_cq_tail - READ_ONCE(rings->cq.head) ==
-		    rings->cq_ring_entries))
-			return false;
-	}
+	if (!force && __io_cqring_events(ctx) == rings->cq_ring_entries)
+		return false;
 
 	spin_lock_irqsave(&ctx->completion_lock, flags);
-
-	/* if force is set, the ring is going away. always drop after that */
-	if (force)
-		ctx->cq_overflow_flushed = 1;
-
-	cqe = NULL;
 	list_for_each_entry_safe(req, tmp, &ctx->cq_overflow_list, compl.list) {
 		if (!io_match_task(req, tsk, files))
 			continue;
@@ -1758,9 +1744,14 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
 		}
 	}
 
-	io_commit_cqring(ctx);
-	io_cqring_mark_overflow(ctx);
+	all_flushed = list_empty(&ctx->cq_overflow_list);
+	if (all_flushed) {
+		clear_bit(0, &ctx->sq_check_overflow);
+		clear_bit(0, &ctx->cq_check_overflow);
+		ctx->rings->sq_flags &= ~IORING_SQ_CQ_OVERFLOW;
+	}
 
+	io_commit_cqring(ctx);
 	spin_unlock_irqrestore(&ctx->completion_lock, flags);
 	io_cqring_ev_posted(ctx);
 
@@ -1770,7 +1761,7 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
 		io_put_req(req);
 	}
 
-	return cqe != NULL;
+	return all_flushed;
 }
 
 static void __io_cqring_fill_event(struct io_kiocb *req, long res, long cflags)
@@ -2320,8 +2311,6 @@ static void io_double_put_req(struct io_kiocb *req)
 
 static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush)
 {
-	struct io_rings *rings = ctx->rings;
-
 	if (test_bit(0, &ctx->cq_check_overflow)) {
 		/*
 		 * noflush == true is from the waitqueue handler, just ensure
@@ -2336,7 +2325,7 @@ static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush)
 
 	/* See comment at the top of this file */
 	smp_rmb();
-	return ctx->cached_cq_tail - READ_ONCE(rings->cq.head);
+	return __io_cqring_events(ctx);
 }
 
 static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
@@ -3136,9 +3125,7 @@ static ssize_t io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov,
 		iov[0].iov_len = kbuf->len;
 		return 0;
 	}
-	if (!req->rw.len)
-		return 0;
-	else if (req->rw.len > 1)
+	if (req->rw.len != 1)
 		return -EINVAL;
 
 #ifdef CONFIG_COMPAT
@@ -3784,6 +3771,8 @@ static int io_shutdown(struct io_kiocb *req, bool force_nonblock)
 		return -ENOTSOCK;
 
 	ret = __sys_shutdown_sock(sock, req->shutdown.how);
+	if (ret < 0)
+		req_set_fail_links(req);
 	io_req_complete(req, ret);
 	return 0;
 #else
@@ -6107,15 +6096,15 @@ static void io_req_drop_files(struct io_kiocb *req)
 	struct io_uring_task *tctx = req->task->io_uring;
 	unsigned long flags;
 
+	put_files_struct(req->work.identity->files);
+	put_nsproxy(req->work.identity->nsproxy);
 	spin_lock_irqsave(&ctx->inflight_lock, flags);
 	list_del(&req->inflight_entry);
-	if (atomic_read(&tctx->in_idle))
-		wake_up(&tctx->wait);
 	spin_unlock_irqrestore(&ctx->inflight_lock, flags);
 	req->flags &= ~REQ_F_INFLIGHT;
-	put_files_struct(req->work.identity->files);
-	put_nsproxy(req->work.identity->nsproxy);
 	req->work.flags &= ~IO_WQ_WORK_FILES;
+	if (atomic_read(&tctx->in_idle))
+		wake_up(&tctx->wait);
 }
 
 static void __io_clean_op(struct io_kiocb *req)
@@ -6343,19 +6332,28 @@ static struct io_wq_work *io_wq_submit_work(struct io_wq_work *work)
 	}
 
 	if (ret) {
+		struct io_ring_ctx *lock_ctx = NULL;
+
+		if (req->ctx->flags & IORING_SETUP_IOPOLL)
+			lock_ctx = req->ctx;
+
 		/*
-		 * io_iopoll_complete() does not hold completion_lock to complete
-		 * polled io, so here for polled io, just mark it done and still let
-		 * io_iopoll_complete() complete it.
+		 * io_iopoll_complete() does not hold completion_lock to
+		 * complete polled io, so here for polled io, we can not call
+		 * io_req_complete() directly, otherwise there maybe concurrent
+		 * access to cqring, defer_list, etc, which is not safe. Given
+		 * that io_iopoll_complete() is always called under uring_lock,
+		 * so here for polled io, we also get uring_lock to complete
+		 * it.
 		 */
-		if (req->ctx->flags & IORING_SETUP_IOPOLL) {
-			struct kiocb *kiocb = &req->rw.kiocb;
+		if (lock_ctx)
+			mutex_lock(&lock_ctx->uring_lock);
 
-			kiocb_done(kiocb, ret, NULL);
-		} else {
-			req_set_fail_links(req);
-			io_req_complete(req, ret);
-		}
+		req_set_fail_links(req);
+		io_req_complete(req, ret);
+
+		if (lock_ctx)
+			mutex_unlock(&lock_ctx->uring_lock);
 	}
 
 	return io_steal_work(req);
@@ -6824,8 +6822,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
 
 	/* if we have a backlog and couldn't flush it all, return BUSY */
 	if (test_bit(0, &ctx->sq_check_overflow)) {
-		if (!list_empty(&ctx->cq_overflow_list) &&
-		    !io_cqring_overflow_flush(ctx, false, NULL, NULL))
+		if (!io_cqring_overflow_flush(ctx, false, NULL, NULL))
 			return -EBUSY;
 	}
 
@@ -8155,10 +8152,13 @@ static void io_unaccount_mem(struct io_ring_ctx *ctx, unsigned long nr_pages,
 		__io_unaccount_mem(ctx->user, nr_pages);
 
 	if (ctx->mm_account) {
-		if (acct == ACCT_LOCKED)
+		if (acct == ACCT_LOCKED) {
+			mmap_write_lock(ctx->mm_account);
 			ctx->mm_account->locked_vm -= nr_pages;
-		else if (acct == ACCT_PINNED)
+			mmap_write_unlock(ctx->mm_account);
+		}else if (acct == ACCT_PINNED) {
 			atomic64_sub(nr_pages, &ctx->mm_account->pinned_vm);
+		}
 	}
 }
 
@@ -8174,10 +8174,13 @@ static int io_account_mem(struct io_ring_ctx *ctx, unsigned long nr_pages,
 	}
 
 	if (ctx->mm_account) {
-		if (acct == ACCT_LOCKED)
+		if (acct == ACCT_LOCKED) {
+			mmap_write_lock(ctx->mm_account);
 			ctx->mm_account->locked_vm += nr_pages;
-		else if (acct == ACCT_PINNED)
+			mmap_write_unlock(ctx->mm_account);
+		} else if (acct == ACCT_PINNED) {
 			atomic64_add(nr_pages, &ctx->mm_account->pinned_vm);
+		}
 	}
 
 	return 0;
@@ -8643,10 +8646,19 @@ static void io_ring_exit_work(struct work_struct *work)
 	io_ring_ctx_free(ctx);
 }
 
+static bool io_cancel_ctx_cb(struct io_wq_work *work, void *data)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+
+	return req->ctx == data;
+}
+
 static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 {
 	mutex_lock(&ctx->uring_lock);
 	percpu_ref_kill(&ctx->refs);
+	/* if force is set, the ring is going away. always drop after that */
+	ctx->cq_overflow_flushed = 1;
 	if (ctx->rings)
 		io_cqring_overflow_flush(ctx, true, NULL, NULL);
 	mutex_unlock(&ctx->uring_lock);
@@ -8655,7 +8667,7 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 	io_poll_remove_all(ctx, NULL, NULL);
 
 	if (ctx->io_wq)
-		io_wq_cancel_all(ctx->io_wq);
+		io_wq_cancel_cb(ctx->io_wq, io_cancel_ctx_cb, ctx, true);
 
 	/* if we failed setting up the ctx, we might not have any rings */
 	io_iopoll_try_reap_events(ctx);
@@ -8798,9 +8810,9 @@ static void __io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
 
 		ret |= io_poll_remove_all(ctx, task, NULL);
 		ret |= io_kill_timeouts(ctx, task, NULL);
+		ret |= io_run_task_work();
 		if (!ret)
 			break;
-		io_run_task_work();
 		cond_resched();
 	}
 }
@@ -8849,10 +8861,9 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
 static int io_uring_add_task_file(struct io_ring_ctx *ctx, struct file *file)
 {
 	struct io_uring_task *tctx = current->io_uring;
+	int ret;
 
 	if (unlikely(!tctx)) {
-		int ret;
-
 		ret = io_uring_alloc_task_context(current);
 		if (unlikely(ret))
 			return ret;
@@ -8863,7 +8874,12 @@ static int io_uring_add_task_file(struct io_ring_ctx *ctx, struct file *file)
 
 		if (!old) {
 			get_file(file);
-			xa_store(&tctx->xa, (unsigned long)file, file, GFP_KERNEL);
+			ret = xa_err(xa_store(&tctx->xa, (unsigned long)file,
+						file, GFP_KERNEL));
+			if (ret) {
+				fput(file);
+				return ret;
+			}
 		}
 		tctx->last = file;
 	}
@@ -8986,9 +9002,9 @@ void __io_uring_task_cancel(void)
 		if (inflight != tctx_inflight(tctx))
 			continue;
 		schedule();
+		finish_wait(&tctx->wait, &wait);
 	} while (1);
 
-	finish_wait(&tctx->wait, &wait);
 	atomic_dec(&tctx->in_idle);
 }
 
@@ -9156,10 +9172,13 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 	 */
 	ret = 0;
 	if (ctx->flags & IORING_SETUP_SQPOLL) {
-		io_ring_submit_lock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));
-		if (!list_empty_careful(&ctx->cq_overflow_list))
+		if (!list_empty_careful(&ctx->cq_overflow_list)) {
+			bool needs_lock = ctx->flags & IORING_SETUP_IOPOLL;
+
+			io_ring_submit_lock(ctx, needs_lock);
 			io_cqring_overflow_flush(ctx, false, NULL, NULL);
-		io_ring_submit_unlock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));
+			io_ring_submit_unlock(ctx, needs_lock);
+		}
 		if (flags & IORING_ENTER_SQ_WAKEUP)
 			wake_up(&ctx->sq_data->wait);
 		if (flags & IORING_ENTER_SQ_WAIT)
@@ -9369,55 +9388,52 @@ static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
 	return 0;
 }
 
+static int io_uring_install_fd(struct io_ring_ctx *ctx, struct file *file)
+{
+	int ret, fd;
+
+	fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	ret = io_uring_add_task_file(ctx, file);
+	if (ret) {
+		put_unused_fd(fd);
+		return ret;
+	}
+	fd_install(fd, file);
+	return fd;
+}
+
 /*
  * Allocate an anonymous fd, this is what constitutes the application
  * visible backing of an io_uring instance. The application mmaps this
  * fd to gain access to the SQ/CQ ring details. If UNIX sockets are enabled,
  * we have to tie this fd to a socket for file garbage collection purposes.
  */
-static int io_uring_get_fd(struct io_ring_ctx *ctx)
+static struct file *io_uring_get_file(struct io_ring_ctx *ctx)
 {
 	struct file *file;
+#if defined(CONFIG_UNIX)
 	int ret;
-	int fd;
 
-#if defined(CONFIG_UNIX)
 	ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
 				&ctx->ring_sock);
 	if (ret)
-		return ret;
+		return ERR_PTR(ret);
 #endif
 
-	ret = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
-	if (ret < 0)
-		goto err;
-	fd = ret;
-
 	file = anon_inode_getfile("[io_uring]", &io_uring_fops, ctx,
 					O_RDWR | O_CLOEXEC);
-	if (IS_ERR(file)) {
-		put_unused_fd(fd);
-		ret = PTR_ERR(file);
-		goto err;
-	}
-
 #if defined(CONFIG_UNIX)
-	ctx->ring_sock->file = file;
-#endif
-	ret = io_uring_add_task_file(ctx, file);
-	if (ret) {
-		fput(file);
-		put_unused_fd(fd);
-		goto err;
+	if (IS_ERR(file)) {
+		sock_release(ctx->ring_sock);
+		ctx->ring_sock = NULL;
+	} else {
+		ctx->ring_sock->file = file;
 	}
-	fd_install(fd, file);
-	return fd;
-err:
-#if defined(CONFIG_UNIX)
-	sock_release(ctx->ring_sock);
-	ctx->ring_sock = NULL;
 #endif
-	return ret;
+	return file;
 }
 
 static int io_uring_create(unsigned entries, struct io_uring_params *p,
@@ -9425,6 +9441,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p,
 {
 	struct user_struct *user = NULL;
 	struct io_ring_ctx *ctx;
+	struct file *file;
 	bool limit_mem;
 	int ret;
 
@@ -9572,13 +9589,22 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p,
 		goto err;
 	}
 
+	file = io_uring_get_file(ctx);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto err;
+	}
+
 	/*
 	 * Install ring fd as the very last thing, so we don't risk someone
 	 * having closed it before we finish setup
 	 */
-	ret = io_uring_get_fd(ctx);
-	if (ret < 0)
-		goto err;
+	ret = io_uring_install_fd(ctx, file);
+	if (ret < 0) {
+		/* fput will clean it up */
+		fput(file);
+		return ret;
+	}
 
 	trace_io_uring_create(ret, ctx, p->sq_entries, p->cq_entries, p->flags);
 	return ret;