If TIF_NOTIFY_RESUME is set, then we need to call resume_user_mode_work()
for PF_IO_WORKER threads. They never return to usermode, hence never get
a chance to process any items that are marked by this flag. Most notably
this includes the final put of files, but also any throttling markers set
by block cgroups.
Cc: stable@xxxxxxxxxxxxxxx # 5.10+
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index ab4b2a1c3b7e..e532dea68773 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -3,6 +3,7 @@
#include <linux/errno.h>
#include <linux/lockdep.h>
+#include <linux/resume_user_mode.h>
#include <linux/io_uring_types.h>
#include <uapi/linux/eventpoll.h>
#include "io-wq.h"
@@ -270,6 +271,13 @@ static inline int io_run_task_work(void)
*/
if (test_thread_flag(TIF_NOTIFY_SIGNAL))
clear_notify_signal();
+ /*
+ * PF_IO_WORKER never returns to userspace, so check here if we have
+ * notify work that needs processing.
+ */
+ if (current->flags & PF_IO_WORKER &&
+ test_thread_flag(TIF_NOTIFY_RESUME))
+ resume_user_mode_work(NULL);
if (task_work_pending(current)) {
__set_current_state(TASK_RUNNING);
task_work_run();
--
Jens Axboe
