From 2b047c8a8c2769319a6ed17c47773c285b047080 Mon Sep 17 00:00:00 2001 From: Gregory Price Date: Sun, 12 Jul 2026 11:44:59 -0400 Subject: mm/memory_hotplug: add __add_memory_driver_managed() with online_type arg Existing callers of add_memory_driver_managed cannot select the preferred online type (ZONE_NORMAL vs ZONE_MOVABLE), requiring it to hot-add memory as offline blocks, and then follow up by onlining each memory block individually. Most drivers prefer the system default, but the CXL driver wants to plumb a preferred policy through the dax kmem driver. Refactor APIs to add a new interface which allows the dax kmem module to select a preferred policy. Overriding the configured auto-online policy is only safe for known in-tree modules, where we know the override reflects a different, user-requested policy. We do not want arbitrary out-of-tree drivers silently overriding the system-wide onlining policy, so restrict the new interface to the kmem module using EXPORT_SYMBOL_FOR_MODULES() rather than a plain EXPORT_SYMBOL_GPL(). Other in-tree modules (e.g. cxl_core) can be added to the allowed list as the need arises. Refactor add_memory_driver_managed, extract __add_memory_driver_managed - Add proper kernel-doc for add_memory_driver_managed while refactoring - New helper accepts an explicit online_type. - New helper validates online_type is between OFFLINE and ONLINE_MOVABLE Refactor: add_memory_resource, extract __add_memory_resource - new helper accepts an explicit online_type Original APIs now explicitly pass the system-default to new helpers. No functional change for existing users. Link: https://lore.kernel.org/20260712154505.3564379-6-gourry@gourry.net Signed-off-by: Gregory Price Acked-by: David Hildenbrand (Arm) Reviewed-by: Pankaj Gupta Reviewed-by: Dave Jiang Reviewed-by: Dan Williams Cc: Alison Schofield Cc: Danilo Krummrich Cc: Greg Kroah-Hartman Cc: Hannes Reinecke Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vishal Verma Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- include/linux/memory_hotplug.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/memory_hotplug.h') diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 5240aa28bc90..d69b273ed304 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -295,6 +295,9 @@ extern int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags); extern int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags); extern int add_memory_resource(int nid, struct resource *resource, mhp_t mhp_flags); +int __add_memory_driver_managed(int nid, u64 start, u64 size, + const char *resource_name, mhp_t mhp_flags, + enum mmop online_type); extern int add_memory_driver_managed(int nid, u64 start, u64 size, const char *resource_name, mhp_t mhp_flags); -- cgit v1.2.3