On 28/01/2020 22:42, Jens Axboe wrote:
> I didn't like it becoming a bit too complicated, both in terms of
> implementation and use. And the fact that we'd have to jump through
> hoops to make this work for a full chain.
> 
> So I punted and just added sqe->personality and IOSQE_PERSONALITY.
> This makes it way easier to use. Same branch:
> 
> https://git.kernel.dk/cgit/linux-block/log/?h=for-5.6/io_uring-vfs-creds
> 
> I'd feel much better with this variant for 5.6.
> 

Checked out ("don't use static creds/mm assignments")

1. do we miscount cred refs? We grab one in get_current_cred() for each async
request, but if (worker->creds != work->creds) it will never be put.

2. shouldn't worker->creds be named {old,saved,etc}_creds? It's set as

    worker->creds = override_creds(work->creds);

Where override_creds() returns previous creds. And if so, then the following
fast check looks strange:

    worker->creds != work->creds

-- 
Pavel Begunkov