diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 6c9d6dfad68e89cbefbfdb7d40243e32a3e0e2e3..69f5b73a609e2f6d507990771c4b308c29fd4ad0 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -667,6 +667,8 @@ static void io_cqring_overflow_kill(struct io_ring_ctx *ctx)
 	struct io_overflow_cqe *ocqe;
 	LIST_HEAD(list);
 
+	lockdep_assert_held(&ctx->uring_lock);
+
 	spin_lock(&ctx->completion_lock);
 	list_splice_init(&ctx->cq_overflow_list, &list);
 	clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
@@ -683,6 +685,8 @@ static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
 {
 	size_t cqe_size = sizeof(struct io_uring_cqe);
 
+	lockdep_assert_held(&ctx->uring_lock);
+
 	if (__io_cqring_events(ctx) == ctx->cq_entries)
 		return;
 
@@ -701,6 +705,21 @@ static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
 		memcpy(cqe, &ocqe->cqe, cqe_size);
 		list_del(&ocqe->list);
 		kfree(ocqe);
+
+		/*
+		 * For silly syzbot cases that deliberately overflow by huge
+		 * amounts, check if we need to resched and drop and
+		 * reacquire the locks if so. Nothing real would ever hit this.
+		 * Ideally we'd have a non-posting unlock for this, but hard
+		 * to care for a non-real case.
+		 */
+		if (need_resched()) {
+			io_cq_unlock_post(ctx);
+			mutex_unlock(&ctx->uring_lock);
+			cond_resched();
+			mutex_lock(&ctx->uring_lock);
+			io_cq_lock(ctx);
+		}
 	}
 
 	if (list_empty(&ctx->cq_overflow_list)) {
@@ -712,12 +731,9 @@ static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
 
 static void io_cqring_do_overflow_flush(struct io_ring_ctx *ctx)
 {
-	/* iopoll syncs against uring_lock, not completion_lock */
-	if (ctx->flags & IORING_SETUP_IOPOLL)
-		mutex_lock(&ctx->uring_lock);
+	mutex_lock(&ctx->uring_lock);
 	__io_cqring_overflow_flush(ctx);
-	if (ctx->flags & IORING_SETUP_IOPOLL)
-		mutex_unlock(&ctx->uring_lock);
+	mutex_unlock(&ctx->uring_lock);
 }
 
 static void io_cqring_overflow_flush(struct io_ring_ctx *ctx)
@@ -1596,6 +1612,8 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 	unsigned int nr_events = 0;
 	unsigned long check_cq;
 
+	lockdep_assert_held(&ctx->uring_lock);
+
 	if (!io_allowed_run_tw(ctx))
 		return -EEXIST;