On Tue, Jun 17, 2025 at 05:43:32PM +0200, David Hildenbrand wrote:
> In 2009, we converted a VM_BUG_ON(!pfn_valid(pfn)) to the current
> highest_memmap_pfn sanity check in commit 22b31eec63e5 ("badpage:
> vm_normal_page use print_bad_pte"), because highest_memmap_pfn was
> readily available.
>
> Nowadays, this is the last remaining highest_memmap_pfn user, and this
> sanity check is not really triggering ... frequently.
>
> Let's convert it to VM_WARN_ON_ONCE(!pfn_valid(pfn)), so we can
> simplify and get rid of highest_memmap_pfn. Checking for
> pfn_to_online_page() might be even better, but it would not handle
> ZONE_DEVICE properly.
>
> Do the same in vm_normal_page_pmd(), where we don't even report a
> problem at all ...
>
> What might be better in the future is having a runtime option like
> page-table-check to enable such checks dynamically on-demand. Something
> for the future.
>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
Reviewed-by: Oscar Salvador <osalva...@suse.de>
--
Oscar Salvador
SUSE Labs
