MAINTAINERS: add mm ksm section

As part of the ongoing efforts to sub-divide memory management
maintainership and reviewership, establish a section for Kernel Samepage
Merging (KSM) and add appropriate maintainers and reviewers.

Link: https://lkml.kernel.org/r/20250515190404.203596-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: Xu Xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: ljskernel

MAINTAINERS

@@ -15562,6 +15562,21 @@ W:	http://www.linux-mm.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
 F:	mm/gup.c
 
+MEMORY MANAGEMENT - KSM (Kernel Samepage Merging)
+M:	Andrew Morton <akpm@linux-foundation.org>
+M:	David Hildenbrand <david@redhat.com>
+R:	Xu Xin <xu.xin16@zte.com.cn>
+R:	Chengming Zhou <chengming.zhou@linux.dev>
+L:	linux-mm@kvack.org
+S:	Maintained
+W:	http://www.linux-mm.org
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
+F:	Documentation/admin-guide/mm/ksm.rst
+F:	Documentation/mm/ksm.rst
+F:	include/linux/ksm.h
+F:	include/trace/events/ksm.h
+F:	mm/ksm.c
+
 MEMORY MANAGEMENT - NUMA MEMBLOCKS AND NUMA EMULATION
 M:	Andrew Morton <akpm@linux-foundation.org>
 M:	Mike Rapoport <rppt@kernel.org>