Re: [PATCH] x86/mm: Do not verify W^X at boot up

[Linus Torvalds]

On Tue, Oct 25, 2022 at 10:48 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> mm_alloc() uses allocate_mm() which requires a kmem_cache to be set-up.

Well, that seems to be just a strange effect of mm_cachep being set up
by the oddly named "proc_caches_init" (I say oddly named because these
days I associate "proc" with proc-fs, but I think it actually comes
from "process").

That would actually probably make more sense if it was part of
mm_init(), much earlier (where we do "kmem_cache_init()")

So this is another oddity in how we do "mm_init()", but we haven't
actually initialized _that_ part of the mm setup.

Extra bonus points for another strange thing: we have "fork_init()",
but that too doesn't actually initialize the mm_cachep that fork()
actually uses. It does initialize the process one
(task_struct_cachep). So that kind of makes sense, but yeah, the
mm_alloc() cachep should have been set up by mm_init.

I think this is all "we just ended up randomly initializing things due
to hysterical raisins"

              Linus