On Thu, Jun 17, 2021 at 09:49:07PM -0500, Mike Christie wrote:

Again it's io_uring. Check out fs/io_uring.c:__io_account_mem(). For RLIMIT_MEMLOCK
it just does the check and increments the user's counter itself. It's simple like
option 2, and it handles the issue where the process doing the ioctl wasn't having
its RLIMIT_NPROC checked/updated.

This can work too. It doesn't cover cases where code called indirectly
acquires resources, but that's probably fine for the vhost worker thread
case.

Stefan