Re: [RFC][PATCH] x86/mm: Sync all vmalloc mappings before text_poke()

Peter Zijlstra
2020-04-29T18:52:12Z

> > Basically, it's a big bitmask, where each bit represents a possible process
> > id (can be 2 gigs if we allow all positive ints!).
>
> I think you mean 2 giga-bit, for 256MB worth of memory, right ?
>
> And AFAIU the PID_MAX_LIMIT is at a maximum of 4 million PIDs in
> include/linux/threads.h, which means 512MB worth of memory for a
> bitmask.

PID space is limited to 30 bits per FUTEX_TID_MASK, still, stupid large
:-)