Re: [PATCH v3 1/2] arm64: pageattr: Use pagewalk API to change memory permissions

On Fri, Jun 13, 2025 at 05:27:27PM +0100, Lorenzo Stoakes wrote:

On Fri, Jun 13, 2025 at 07:13:51PM +0530, Dev Jain wrote:

quoted

+		if (WARN_ON_ONCE((next - addr) != PGDIR_SIZE))
+			return -EINVAL;

I guess the point here is to assert that the searched range _entirely
spans_ the folio that the higher order leaf page table entry describes.

I'm guessing this is desired.

But I'm not sure this should be a warning?

What if you happen to walk a range that isn't aligned like this?

My understandging is that the caller must ensure that addr is
pud/pmd/pte-aligned. But, imho, since -EINVAL is returned, I don't think
the WARN_ON_ONCE() is needed.

-- 
~karim