[  115.195073] 99 done
[  115.317571] ------------[ cut here ]------------
[  115.327449] WARNING: CPU: 3 PID: 130 at kernel/workqueue.c:4453 destroy_workqueue+0xf8/0x2d0
[  115.328262] Modules linked in: wq_issue(O-)
[  115.330528] CPU: 3 PID: 130 Comm: rmmod Tainted: G           O      5.10.0-03441-g527301dba422-dirty #131
[  115.331028] Hardware name: linux,dummy-virt (DT)
[  115.331875] pstate: 20000085 (nzCv daIf -PAN -UAO -TCO BTYPE=--)
[  115.332274] pc : destroy_workqueue+0xf8/0x2d0
[  115.332507] lr : destroy_workqueue+0xac/0x2d0
[  115.332735] sp : ffff8000135dbda0
[  115.332963] x29: ffff8000135dbda0 x28: ffff0000c085eac0
[  115.333348] x27: 0000000000000000 x26: 0000000000000000
[  115.333627] x25: 0000000000000000 x24: 0000000000000000
[  115.333903] x23: ffff0000c0027620 x22: ffff800011b81068
[  115.334180] x21: ffff0000c0027600 x20: ffff00027ebdd900
[  115.334459] x19: ffff00027ebdd924 x18: 0000000000000000
[  115.334777] x17: 0000000000000000 x16: 0000000000000000
[  115.335195] x15: 0000000000000173 x14: 0000000000000251
[  115.335638] x13: 0000000000000001 x12: 0000000000000000
[  115.335912] x11: 0000000000000001 x10: 000000000000033e
[  115.336208] x9 : 00000000000f1000 x8 : 0000000000000003
[  115.336483] x7 : 00000000ffffffff x6 : ffff00027ebd9118
[  115.336858] x5 : 0000000000000003 x4 : 0000000000000000
[  115.337361] x3 : ffff00027ebd8000 x2 : ffff00027ebdd958
[  115.337649] x1 : 0000000000000001 x0 : 0000000000000000
[  115.338143] Call trace:
[  115.338498]  destroy_workqueue+0xf8/0x2d0
[  115.339541]  wq_test_exit+0x10/0x24 [wq_issue]
[  115.339779]  __arm64_sys_delete_module+0x184/0x250
[  115.340020]  do_el0_svc+0x84/0x1d0
[  115.340201]  el0_svc+0x10/0x1c
[  115.340356]  el0_sync_handler+0xa8/0xf0
[  115.340549]  el0_sync+0x158/0x180
[  115.340870] ---[ end trace ad43b955b80573a2 ]---
[  115.341484] destroy_workqueue: my_workqueue has the following busy pwq
[  115.341840]   pwq 6: cpus=3 node=0 flags=0x0 nice=0 active=1/1 refcnt=2
[  115.342862]     pending: my_work_function
[  115.346575] Sanity checks
[  115.348693] Showing busy workqueues and worker pools:
[  115.349232] workqueue events_power_efficient: flags=0x82
[  115.350752]   pwq 8: cpus=0-3 flags=0x4 nice=0 active=1/256 refcnt=3
[  115.351409]     pending: neigh_periodic_work
[  115.352947] wq_test_exit

+#include <linux/module.h>
+#include <linux/delay.h>
+
+#define NR_WORK 100
+
+struct workqueue_struct *my_workqueue;
+
+struct my_work_struct {
+	struct work_struct work;
+	int index;
+};
+struct my_work_struct my_work[NR_WORK];
+
+void my_work_function(struct work_struct *work)
+{
+	msleep(100);
+}
+
+static int wq_test_init(void)
+{
+	int i;
+
+	pr_info("wq_test_init\n");
+
+	my_workqueue = create_workqueue("my_workqueue");
+
+	for (i = 0; i < NR_WORK; i++) {
+		INIT_WORK((struct work_struct *)(my_work + i), my_work_function);
+		my_work[i].index = i;
+		// queue_work(ret_my_workqueue(), (struct work_struct *)(my_work + i));
+		queue_work(my_workqueue, (struct work_struct *)(my_work + i));
+	}
+
+	pr_info("wq_test_init done\n");
+	return 0;
+}
+
+static void wq_test_exit(void)
+{
+	flush_work((struct work_struct *)(my_work + (NR_WORK - 1)));
+	destroy_workqueue(my_workqueue);
+
+	pr_info("wq_test_exit done\n");
+	return;
+}
+
+module_init(wq_test_init);
+module_exit(wq_test_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("workqueue issue");