From: Pavel Begunkov <asml.silence@xxxxxxxxx>
[ Upstream commit d434ab6db524ab1efd0afad4ffa1ee65ca6ac097 ]
__io_req_task_submit() run by task_work can set mm and files, but
io_sq_thread() in some cases, and because __io_sq_thread_acquire_mm()
and __io_sq_thread_acquire_files() do a simple current->mm/files check
it may end up submitting IO with mm/files of another task.
We also need to drop it after in the end to drop potentially grabbed
references to them.
Cc: stable@xxxxxxxxxxxxxxx # 5.9+
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/io_uring.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6c356b9e87b39..cab640c10bc0f 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6841,6 +6841,7 @@ static int io_sq_thread(void *data)
if (ret & SQT_SPIN) {
io_run_task_work();
+ io_sq_thread_drop_mm();
cond_resched();
} else if (ret == SQT_IDLE) {
if (kthread_should_park())
@@ -6855,6 +6856,7 @@ static int io_sq_thread(void *data)
}
io_run_task_work();
+ io_sq_thread_drop_mm();
if (cur_css)
io_sq_thread_unassociate_blkcg();
--
2.27.0
