Re: [PATCH v3 04/11] arm64/mm: Add set_memory_device() and set_memory_normal()

[Mike Rapoport <rppt@kernel.org>]

On Mon, Jul 06, 2026 at 03:49:24PM +0200, Thierry Reding wrote:
> On Fri, Jul 03, 2026 at 06:13:31PM +0100, Will Deacon wrote:
> > >
> > > How about if I extract a common helper and provide set_memory_p() and
> > > set_memory_np() in terms of those. Those are available on x86 and
> > > PowerPC as well, so fairly standard. I suppose at that point we're
> > > closer to set_memory_valid().
> > 
> > Why not just call set_direct_map_invalid_noflush() +
> > flush_tlb_kernel_range() for each page? We already have APIs for this.
> 
> Having a "standard" helper with a fixed and documented purposed seemed
> like a preferable approach for this particular case. We also may want to
> make the driver that uses this buildable as a module, in which case we'd
> need to export these rather low-level APIs. And then there's also the
> fact that we typically call this on a rather large region of memory
> (usually something like 512 MiB), so doing it page-by-page is rather
> suboptimal.

There are discussions about adding numpages to set_direct_map, e.g.

https://lore.kernel.org/linux-mm/20260410151746.61150-2-kalyazin@amazon.com/
 
-- 
Sincerely yours,
Mike.