On Thu, Oct 24, 2024 at 7:08 PM Jens Axboe <axboe@xxxxxxxxx> wrote: > Add IORING_REGISTER_RESIZE_RINGS, which allows an application to resize > the existing rings. It takes a struct io_uring_params argument, the same > one which is used to setup the ring initially, and resizes rings > according to the sizes given. [...] > + * We'll do the swap. Clear out existing mappings to prevent mmap > + * from seeing them, as we'll unmap them. Any attempt to mmap existing > + * rings beyond this point will fail. Not that it could proceed at this > + * point anyway, as we'll hold the mmap_sem until we've done the swap. > + * Likewise, hold the completion * lock over the duration of the actual > + * swap. > + */ > + mmap_write_lock(current->mm); Why does the mmap lock for current->mm suffice here? I see nothing in io_uring_mmap() that limits mmap() to tasks with the same mm_struct.
