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Message-Id: <20201031113459.607784722@linuxfoundation.org> Date: Sat, 31 Oct 2020 12:35:34 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Jens Axboe <axboe@...nel.dk> Subject: [PATCH 5.8 02/70] io_uring: dont run task work on an exiting task From: Jens Axboe <axboe@...nel.dk> commit 6200b0ae4ea28a4bfd8eb434e33e6201b7a6a282 upstream. This isn't safe, and isn't needed either. We are guaranteed that any work we queue is on a live task (and will be run), or it goes to our backup io-wq threads if the task is exiting. Signed-off-by: Jens Axboe <axboe@...nel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- fs/io_uring.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1762,6 +1762,12 @@ static int io_put_kbuf(struct io_kiocb * static inline bool io_run_task_work(void) { + /* + * Not safe to run on exiting task, and the task_work handling will + * not add work to such a task. + */ + if (unlikely(current->flags & PF_EXITING)) + return false; if (current->task_works) { __set_current_state(TASK_RUNNING); task_work_run(); @@ -7791,6 +7797,8 @@ static void io_uring_cancel_files(struct io_put_req(cancel_req); } + /* cancellations _may_ trigger task work */ + io_run_task_work(); schedule(); finish_wait(&ctx->inflight_wait, &wait); }
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