Re: [PATCH v7 2/8] mm: Add a ptdesc flag to mark kernel page tables

[David Hildenbrand <david@redhat.com>]

On 22.10.25 10:26, Lu Baolu wrote:
> From: Dave Hansen <dave.hansen@linux.intel.com>
> 
> The page tables used to map the kernel and userspace often have very
> different handling rules. There are frequently *_kernel() variants of
> functions just for kernel page tables. That's not great and has lead
> to code duplication.
> 
> Instead of having completely separate call paths, allow a 'ptdesc' to
> be marked as being for kernel mappings. Introduce helpers to set and
> clear this status.
> 
> Note: this uses the PG_referenced bit. Page flags are a great fit for
> this since it is truly a single bit of information.  Use PG_referenced
> itself because it's a fairly benign flag (as opposed to things like
> PG_lock). It's also (according to Willy) unlikely to go away any time
> soon.
> 
> PG_referenced is not in PAGE_FLAGS_CHECK_AT_FREE. It does not need to
> be cleared before freeing the page, and pages coming out of the
> allocator should have it cleared. Regardless, introduce an API to
> clear it anyway. Having symmetry in the API makes it easier to change
> the underlying implementation later, like if there was a need to move
> to a PAGE_FLAGS_CHECK_AT_FREE bit.
> 
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>

Just a process thing: if you modified patches such that you are 
considered a co-author, there should probably be a

	Co-developed-by: Lu Baolu <baolu.lu@linux.intel.com>

above your SOB.

See "When to use Acked-by:, Cc:, and Co-developed-by:" in 
Documentation/process/submitting-patches.rst

-- 
Cheers

David / dhildenb