doc: Move SLUB documentation to the admin guide

This section is supposed to be for internal documentation, while the
document is advice for sysadmins.  Move it to the appropriate place.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20250611155916.2579160-2-willy@infradead.org
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Documentation/ABI/testing/sysfs-kernel-slab

@@ -37,7 +37,8 @@ Description:
 		The alloc_calls file is read-only and lists the kernel code
 		locations from which allocations for this cache were performed.
 		The alloc_calls file only contains information if debugging is
-		enabled for that cache (see Documentation/mm/slub.rst).
+		enabled for that cache (see
+		Documentation/admin-guide/mm/slab.rst).
 
 What:		/sys/kernel/slab/<cache>/alloc_fastpath
 Date:		February 2008
@@ -219,7 +220,7 @@ Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
 Description:
 		The free_calls file is read-only and lists the locations of
 		object frees if slab debugging is enabled (see
-		Documentation/mm/slub.rst).
+		Documentation/admin-guide/mm/slab.rst).
 
 What:		/sys/kernel/slab/<cache>/free_fastpath
 Date:		February 2008

Documentation/admin-guide/kernel-parameters.txt

@@ -6558,14 +6558,14 @@
 			slab_debug can create guard zones around objects and
 			may poison objects when not in use. Also tracks the
 			last alloc / free. For more information see
-			Documentation/mm/slub.rst.
+			Documentation/admin-guide/mm/slab.rst.
 			(slub_debug legacy name also accepted for now)
 
 	slab_max_order= [MM]
 			Determines the maximum allowed order for slabs.
 			A high setting may cause OOMs due to memory
 			fragmentation. For more information see
-			Documentation/mm/slub.rst.
+			Documentation/admin-guide/mm/slab.rst.
 			(slub_max_order legacy name also accepted for now)
 
 	slab_merge	[MM]
@@ -6580,13 +6580,14 @@
 			the number of objects indicated. The higher the number
 			of objects the smaller the overhead of tracking slabs
 			and the less frequently locks need to be acquired.
-			For more information see Documentation/mm/slub.rst.
+			For more information see
+			Documentation/admin-guide/mm/slab.rst.
 			(slub_min_objects legacy name also accepted for now)
 
 	slab_min_order=	[MM]
 			Determines the minimum page order for slabs. Must be
 			lower or equal to slab_max_order. For more information see
-			Documentation/mm/slub.rst.
+			Documentation/admin-guide/mm/slab.rst.
 			(slub_min_order legacy name also accepted for now)
 
 	slab_nomerge	[MM]
@@ -6600,7 +6601,8 @@
 			cache (risks via metadata attacks are mostly
 			unchanged). Debug options disable merging on their
 			own.
-			For more information see Documentation/mm/slub.rst.
+			For more information see
+			Documentation/admin-guide/mm/slab.rst.
 			(slub_nomerge legacy name also accepted for now)
 
 	slab_strict_numa	[MM]

Documentation/admin-guide/mm/index.rst

@@ -37,6 +37,7 @@ the Linux memory management.
    numaperf
    pagemap
    shrinker_debugfs
+   slab
    soft-dirty
    swap_numa
    transhuge

Documentation/admin-guide/mm/slab.rst

@@ -1,13 +1,12 @@
-==========================
-Short users guide for SLUB
-==========================
+========================================
+Short users guide for the slab allocator
+========================================
 
-The basic philosophy of SLUB is very different from SLAB. SLAB
-requires rebuilding the kernel to activate debug options for all
-slab caches. SLUB always includes full debugging but it is off by default.
-SLUB can enable debugging only for selected slabs in order to avoid
-an impact on overall system performance which may make a bug more
-difficult to find.
+The slab allocator includes full debugging support (when built with
+CONFIG_SLUB_DEBUG=y) but it is off by default (unless built with
+CONFIG_SLUB_DEBUG_ON=y).  You can enable debugging only for selected
+slabs in order to avoid an impact on overall system performance which
+may make a bug more difficult to find.
 
 In order to switch debugging on one can add an option ``slab_debug``
 to the kernel command line. That will enable full debugging for

Documentation/mm/index.rst

@@ -56,7 +56,6 @@ documentation, or deleted if it has served its purpose.
    page_owner
    page_table_check
    remap_file_pages
-   slub
    split_page_table_lock
    transhuge
    unevictable-lru