[PATCH] io_uring: consider cgroup setting when binding sqpoll cpu

[Hao Xu <haoxu@xxxxxxxxxxxxxxxxx>]

Since sqthread is userspace like thread now, it should respect cgroup
setting, thus we should consider current allowed cpuset when doing
cpu binding for sqthread.

Signed-off-by: Hao Xu <haoxu@xxxxxxxxxxxxxxxxx>
---
 fs/io_uring.c | 41 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 37 insertions(+), 4 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 51c4166f68b5..35d0e7bc283b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -79,6 +79,7 @@
 #include <linux/pagemap.h>
 #include <linux/io_uring.h>
 #include <linux/tracehook.h>
+#include <linux/cpuset.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/io_uring.h>
@@ -6903,15 +6904,35 @@ static int io_sq_thread(void *data)
 	struct io_ring_ctx *ctx;
 	unsigned long timeout = 0;
 	char buf[TASK_COMM_LEN];
+	cpumask_var_t cpus_allowed;
 	DEFINE_WAIT(wait);
 
 	snprintf(buf, sizeof(buf), "iou-sqp-%d", sqd->task_pid);
 	set_task_comm(current, buf);
 
-	if (sqd->sq_cpu != -1)
-		set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));
-	else
-		set_cpus_allowed_ptr(current, cpu_online_mask);
+	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
+		mutex_lock(&sqd->lock);
+		sqd->thread = NULL;
+		list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
+			io_ring_set_wakeup_flag(ctx);
+		io_run_task_work();
+		mutex_unlock(&sqd->lock);
+
+		complete(&sqd->exited);
+		do_exit(1);
+	}
+	cpuset_cpus_allowed(current, cpus_allowed);
+	if (sqd->sq_cpu != -1) {
+		if (!cpumask_test_cpu(sqd->sq_cpu, cpus_allowed)) {
+			sqd->sq_cpu = -1;
+			pr_warn("sqthread %d: bound cpu not allowed\n", current->pid);
+		} else {
+			set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));
+		}
+	}
+	if (sqd->sq_cpu == -1)
+		set_cpus_allowed_ptr(current, cpus_allowed);
+	free_cpumask_var(cpus_allowed);
 	current->flags |= PF_NO_SETAFFINITY;
 
 	mutex_lock(&sqd->lock);
@@ -8060,11 +8081,23 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
 
 		if (p->flags & IORING_SETUP_SQ_AFF) {
 			int cpu = p->sq_thread_cpu;
+			cpumask_var_t cpus_allowed;
 
 			ret = -EINVAL;
 			if (cpu >= nr_cpu_ids || !cpu_online(cpu))
 				goto err_sqpoll;
+			if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
+				ret = -ENOMEM;
+				goto err_sqpoll;
+			}
+			cpuset_cpus_allowed(current, cpus_allowed);
+			if (!cpumask_test_cpu(cpu, cpus_allowed)) {
+				free_cpumask_var(cpus_allowed);
+				goto err_sqpoll;
+			}
+
 			sqd->sq_cpu = cpu;
+			free_cpumask_var(cpus_allowed);
 		} else {
 			sqd->sq_cpu = -1;
 		}
-- 
2.24.4