On Thu, 1 Feb 2018, Igor Stoppa wrote:

quoted

Would it not be better to use compound page allocations here?
page_head(whatever) gets you the head page where you can store all sorts
of information about the chunk of memory.

Can you please point me to this function/macro? I don't seem to be able
to find it, at least not in 4.15

Ok its compound_head(). See also the use in the SLAB and SLUB allocator.

During hardened user copy permission check, I need to confirm if the
memory range that would be exposed to userspace is a legitimate
sub-range of a pmalloc allocation.

If you save the size in the head page struct then you could do that pretty
fast.

I cannot comment on your proposal because I do not know where to find
the reference you made, or maybe I do not understand what you mean :-(

compund pages are higher order pages that are handled as a single page by
the VM. See https://lwn.net/Articles/619514/
--
To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html