From: Pavel Begunkov asml.silence@gmail.com
[ 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@vger.kernel.org # 5.9+ Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- 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();