io_uring/io-wq: only free worker if it was allocated for creation

io_uring/io-wq: only free worker if it was allocated for creation

commit d0bcb674a4e4a672701c53ef464098abdd03e6d5 upstream.

We have two types of task_work based creation, one is using an existing
worker to setup a new one (eg when going to sleep and we have no free
workers), and the other is allocating a new worker. Only the latter
should be freed when we cancel task_work creation for a new worker.

Fixes: 6b05c7c8dcc7 ("io_uring/io-wq: free worker if task_work creation is canceled")
Reported-by: syzbot+d56ec896af3637bdb7e4@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>