On 25.06.25 10:32, Oscar Salvador wrote:
On Tue, Jun 17, 2025 at 05:43:39PM +0200, David Hildenbrand wrote:
The huge zero folio is refcounted (+mapcounted -- is that a word?)
differently than "normal" folios, similarly (but different) to the ordinary
shared zeropage.
For this reason, we special-case these pages in
vm_normal_page*/vm_normal_folio*, and only allow selected callers to
still use them (e.g., GUP can still take a reference on them).
vm_normal_page_pmd() already filters out the huge zero folio. However,
so far we are not marking it as special like we do with the ordinary
shared zeropage. Let's mark it as special, so we can further refactor
vm_normal_page_pmd() and vm_normal_page().
While at it, update the doc regarding the shared zero folios.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
While doing this, would it make sense to update vm_normal_page_pmd()
comments to refelect that pmd_special will also catch huge_zero_folio()?
It only mentions huge pfnmaps.
It might not be worth doing since you remove that code later on, but
maybe if someone stares at this commit alone..
Yes, it should be removed in this patch, thanks!
--
Cheers,
David / dhildenb
