On Sun, 26 Jan 2025 at 06:21, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
>
> > Should we just add some flag to say "don't show this thread in this
> > context"?
>
> Not sure I understand... Looking at is_single_threaded() above I guess
> something like below should work (incomplete, in particular we need to
> chang first_tid() as well).
So yes, I was thinking something similar, but:
> But a PF_HIDDEN sub-thread will still be visible via /proc/$pid_of_PF_HIDDEN
>
> > We obviously still want to see it for management purposes,
> > so it's not like the thing should be entirely invisible,
>
> Can you explain?
I was literally thinking that instead of a "hidden" flag, it would be
a "self-hidden" flag.
So if somebody _else_ (notably the sysadmin) does "ps" they see the
kernel thread as a subthread.
But when you look at your own /proc/self/task/ listing, you only see
your own explicit threads. So that "is_singlethreaded()" logic works.
Maybe that's just too ugly for words, and the kvm workaround is better.
Linus
