On Sat Oct 31, 2026 at 10:13 PM EDT, Gregory Price (Meta) wrote:
> Memory hotplug rebuilds zonelists in place while allocations walk them,
> so a zoneref slot can change between two loads of it.
>
> zonelist_zone() loads the slot with a plain access. The compiler may
> load it again later instead of keeping the zone it already read, so a
> caller can check one zone and then use another, or the NULL terminator.
>
> Use READ_ONCE(). Callers that take a zone from a slot and keep using
> it, such as get_page_from_freelist() with ac->preferred_zoneref, need
> that single load.
>
> Fixes: 11cd8638c37f ("mm, page_alloc: remove stop_machine from
> build_all_zonelists")
> Cc: [email protected]
> Signed-off-by: Gregory Price (Meta) <[email protected]>
> ---
> include/linux/mmzone.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
LGTM.
Acked-by: Zi Yan <[email protected]>
--
Best Regards,
Yan, Zi
