Protection key in io uring kthread

[Jeff Xu <jeffxu@chromium.org>]

Hi
I have a question on the protection key in io_uring. Today, when a
user thread enters the kernel through syscall, PKRU is preserved, and
the kernel  will respect the PKEY protection of memory.

For example:
sys_mprotect_pkey((void *)ptr, size, PROT_READ | PROT_WRITE, pkey);
pkey_write_deny(pkey); <-- disable write access to pkey for this thread.
ret = read(fd, ptr, 1); <-- this will fail in the kernel.

I wonder what is the case for io_uring, since read is now async, will
kthread have the user thread's PKUR ?

In theory, it is possible, i.e. from io_uring_enter syscall. But I
don't know the implementation details of io_uring, hence asking the
expert in this list.

Thanks!
-Jeff