mm/slub: Convert most struct page to struct slab by spatch

The majority of conversion from struct page to struct slab in SLUB
internals can be delegated to a coccinelle semantic patch. This includes
renaming of variables with 'page' in name to 'slab', and similar.

Big thanks to Julia Lawall and Luis Chamberlain for help with
coccinelle.

// Options: --include-headers --no-includes --smpl-spacing include/linux/slub_def.h mm/slub.c
// Note: needs coccinelle 1.1.1 to avoid breaking whitespace, and ocaml for the
// embedded script

// build list of functions to exclude from applying the next rule
@initialize:ocaml@
@@

let ok_function p =
  not (List.mem (List.hd p).current_element ["nearest_obj";"obj_to_index";"objs_per_slab_page";"__slab_lock";"__slab_unlock";"free_nonslab_page";"kmalloc_large_node"])

// convert the type from struct page to struct page in all functions except the
// list from previous rule
// this also affects struct kmem_cache_cpu, but that's ok
@@
position p : script:ocaml() { ok_function p };
@@

- struct page@p
+ struct slab

// in struct kmem_cache_cpu, change the name from page to slab
// the type was already converted by the previous rule
@@
@@

struct kmem_cache_cpu {
...
-struct slab *page;
+struct slab *slab;
...
}

// there are many places that use c->page which is now c->slab after the
// previous rule
@@
struct kmem_cache_cpu *c;
@@

-c->page
+c->slab

@@
@@

struct kmem_cache {
...
- unsigned int cpu_partial_pages;
+ unsigned int cpu_partial_slabs;
...
}

@@
struct kmem_cache *s;
@@

- s->cpu_partial_pages
+ s->cpu_partial_slabs

@@
@@

static void
- setup_page_debug(
+ setup_slab_debug(
 ...)
 {...}

@@
@@

- setup_page_debug(
+ setup_slab_debug(
 ...);

// for all functions (with exceptions), change any "struct slab *page"
// parameter to "struct slab *slab" in the signature, and generally all
// occurences of "page" to "slab" in the body - with some special cases.

@@
identifier fn !~ "free_nonslab_page|obj_to_index|objs_per_slab_page|nearest_obj";
@@
 fn(...,
-   struct slab *page
+   struct slab *slab
    ,...)
 {
<...
- page
+ slab
...>
 }

// similar to previous but the param is called partial_page
@@
identifier fn;
@@

 fn(...,
-   struct slab *partial_page
+   struct slab *partial_slab
    ,...)
 {
<...
- partial_page
+ partial_slab
...>
 }

// similar to previous but for functions that take pointer to struct page ptr
@@
identifier fn;
@@

 fn(...,
-   struct slab **ret_page
+   struct slab **ret_slab
    ,...)
 {
<...
- ret_page
+ ret_slab
...>
 }

// functions converted by previous rules that were temporarily called using
// slab_page(E) so we want to remove the wrapper now that they accept struct
// slab ptr directly
@@
identifier fn =~ "slab_free|do_slab_free";
expression E;
@@

 fn(...,
- slab_page(E)
+ E
  ,...)

// similar to previous but for another pattern
@@
identifier fn =~ "slab_pad_check|check_object";
@@

 fn(...,
- folio_page(folio, 0)
+ slab
  ,...)

// functions that were returning struct page ptr and now will return struct
// slab ptr, including slab_page() wrapper removal
@@
identifier fn =~ "allocate_slab|new_slab";
expression E;
@@

 static
-struct slab *
+struct slab *
 fn(...)
 {
<...
- slab_page(E)
+ E
...>
 }

// rename any former struct page * declarations
@@
@@

struct slab *
(
- page
+ slab
|
- partial_page
+ partial_slab
|
- oldpage
+ oldslab
)
;

// this has to be separate from previous rule as page and page2 appear at the
// same line
@@
@@

struct slab *
-page2
+slab2
;

// similar but with initial assignment
@@
expression E;
@@

struct slab *
(
- page
+ slab
|
- flush_page
+ flush_slab
|
- discard_page
+ slab_to_discard
|
- page_to_unfreeze
+ slab_to_unfreeze
)
= E;

// convert most of struct page to struct slab usage inside functions (with
// exceptions), including specific variable renames
@@
identifier fn !~ "nearest_obj|obj_to_index|objs_per_slab_page|__slab_(un)*lock|__free_slab|free_nonslab_page|kmalloc_large_node";
expression E;
@@

 fn(...)
 {
<...
(
- int pages;
+ int slabs;
|
- int pages = E;
+ int slabs = E;
|
- page
+ slab
|
- flush_page
+ flush_slab
|
- partial_page
+ partial_slab
|
- oldpage->pages
+ oldslab->slabs
|
- oldpage
+ oldslab
|
- unsigned int nr_pages;
+ unsigned int nr_slabs;
|
- nr_pages
+ nr_slabs
|
- unsigned int partial_pages = E;
+ unsigned int partial_slabs = E;
|
- partial_pages
+ partial_slabs
)
...>
 }

// this has to be split out from the previous rule so that lines containing
// multiple matching changes will be fully converted
@@
identifier fn !~ "nearest_obj|obj_to_index|objs_per_slab_page|__slab_(un)*lock|__free_slab|free_nonslab_page|kmalloc_large_node";
@@

 fn(...)
 {
<...
(
- slab->pages
+ slab->slabs
|
- pages
+ slabs
|
- page2
+ slab2
|
- discard_page
+ slab_to_discard
|
- page_to_unfreeze
+ slab_to_unfreeze
)
...>
 }

// after we simply changed all occurences of page to slab, some usages need
// adjustment for slab-specific functions, or use slab_page() wrapper
@@
identifier fn !~ "nearest_obj|obj_to_index|objs_per_slab_page|__slab_(un)*lock|__free_slab|free_nonslab_page|kmalloc_large_node";
@@

 fn(...)
 {
<...
(
- page_slab(slab)
+ slab
|
- kasan_poison_slab(slab)
+ kasan_poison_slab(slab_page(slab))
|
- page_address(slab)
+ slab_address(slab)
|
- page_size(slab)
+ slab_size(slab)
|
- PageSlab(slab)
+ folio_test_slab(slab_folio(slab))
|
- page_to_nid(slab)
+ slab_nid(slab)
|
- compound_order(slab)
+ slab_order(slab)
)
...>
 }

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Luis Chamberlain <mcgrof@kernel.org>

include/linux/slub_def.h

@@ -48,9 +48,9 @@ enum stat_item {
 struct kmem_cache_cpu {
 	void **freelist;	/* Pointer to next available object */
 	unsigned long tid;	/* Globally unique transaction id */
-	struct page *page;	/* The slab from which we are allocating */
+	struct slab *slab;	/* The slab from which we are allocating */
 #ifdef CONFIG_SLUB_CPU_PARTIAL
-	struct page *partial;	/* Partially allocated frozen slabs */
+	struct slab *partial;	/* Partially allocated frozen slabs */
 #endif
 	local_lock_t lock;	/* Protects the fields above */
 #ifdef CONFIG_SLUB_STATS
@@ -100,7 +100,7 @@ struct kmem_cache {
 	/* Number of per cpu partial objects to keep around */
 	unsigned int cpu_partial;
 	/* Number of per cpu partial pages to keep around */
-	unsigned int cpu_partial_pages;
+	unsigned int cpu_partial_slabs;
 #endif
 	struct kmem_cache_order_objects oo;