Re: [PATCH 5.14] io_uring: use right task for exiting checks

[Pavel Begunkov <asml.silence@gmail.com>]

On 7/10/21 2:40 PM, Jens Axboe wrote:
> On Fri, Jul 9, 2021 at 7:46 PM Pavel Begunkov <asml.silence@gmail.com> wrote:
>> When we use delayed_work for fallback execution of requests, current
>> will be not of the submitter task, and so checks in io_req_task_submit()
>> may not behave as expected. Currently, it leaves inline completions not
>> flushed, so making io_ring_exit_work() to hang. Use the submitter task
>> for all those checks.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
>> ---
>>  fs/io_uring.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 7167c61c6d1b..770fdcd7d3e4 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -2016,7 +2016,7 @@ static void io_req_task_submit(struct io_kiocb *req)
>>
>>         /* ctx stays valid until unlock, even if we drop all ours ctx->refs */
>>         mutex_lock(&ctx->uring_lock);
>> -       if (!(current->flags & PF_EXITING) && !current->in_execve)
>> +       if (!(req->task->flags & PF_EXITING) && !req->task->in_execve)
>>                 __io_queue_sqe(req);
>>         else
>>                 io_req_complete_failed(req, -EFAULT);
> 
> I don't think that ->in_execve check is useful anymore now that we don't
> have weak references to the files table, so it should probably just go
> away.

Had such a thought but from the premise that on exec we wait / cancel
all requests. But I'd rather to leave it to a separate commit for-next,
don't you think so?

-- 
Pavel Begunkov