diff mbox series

[v2,17/20] mm/zsmalloc: convert get/set_first_obj_offset() to take zpdesc

Message ID 20240703040613.681396-18-alexs@kernel.org (mailing list archive)
State New
Headers show
Series mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool | expand

Commit Message

alexs@kernel.org July 3, 2024, 4:06 a.m. UTC 
From: Hyeonggon Yoo <42.hyeyoo@gmail.com>

Now that all users of get/set_first_obj_offset() are converted
to use zpdesc, convert them to take zpdesc.

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
---
 mm/zpdesc.h   |  6 +++++-
 mm/zsmalloc.c | 32 ++++++++++++++++----------------
 2 files changed, 21 insertions(+), 17 deletions(-)

Comments

kernel test robot July 5, 2024, 2:43 p.m. UTC | #1 
Hi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/alexs-kernel-org/mm-zsmalloc-add-zpdesc-memory-descriptor-for-zswap-zpool/20240703-182314
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20240703040613.681396-18-alexs%40kernel.org
patch subject: [PATCH v2 17/20] mm/zsmalloc: convert get/set_first_obj_offset() to take zpdesc
config: i386-randconfig-002-20240705 (https://download.01.org/0day-ci/archive/20240705/202407052102.qbT7nLMK-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240705/202407052102.qbT7nLMK-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202407052102.qbT7nLMK-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> mm/zsmalloc.c:471:12: warning: function 'is_first_zpdesc' is not needed and will not be emitted [-Wunneeded-internal-declaration]
     471 | static int is_first_zpdesc(struct zpdesc *zpdesc)
         |            ^~~~~~~~~~~~~~~
   1 warning generated.


vim +/is_first_zpdesc +471 mm/zsmalloc.c

61989a80fb3ac9 drivers/staging/zsmalloc/zsmalloc-main.c Nitin Gupta 2012-01-09  470  
3844a7927dcecc mm/zsmalloc.c                            Alex Shi    2024-07-03 @471  static int is_first_zpdesc(struct zpdesc *zpdesc)
3844a7927dcecc mm/zsmalloc.c                            Alex Shi    2024-07-03  472  {
3844a7927dcecc mm/zsmalloc.c                            Alex Shi    2024-07-03  473  	return PagePrivate(zpdesc_page(zpdesc));
3844a7927dcecc mm/zsmalloc.c                            Alex Shi    2024-07-03  474  }
3844a7927dcecc mm/zsmalloc.c                            Alex Shi    2024-07-03  475
Nathan Chancellor July 5, 2024, 5:15 p.m. UTC | #2 
On Fri, Jul 05, 2024 at 10:43:41PM +0800, kernel test robot wrote:
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on akpm-mm/mm-everything]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/alexs-kernel-org/mm-zsmalloc-add-zpdesc-memory-descriptor-for-zswap-zpool/20240703-182314
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> patch link:    https://lore.kernel.org/r/20240703040613.681396-18-alexs%40kernel.org
> patch subject: [PATCH v2 17/20] mm/zsmalloc: convert get/set_first_obj_offset() to take zpdesc
> config: i386-randconfig-002-20240705 (https://download.01.org/0day-ci/archive/20240705/202407052102.qbT7nLMK-lkp@intel.com/config)
> compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240705/202407052102.qbT7nLMK-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202407052102.qbT7nLMK-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> mm/zsmalloc.c:471:12: warning: function 'is_first_zpdesc' is not needed and will not be emitted [-Wunneeded-internal-declaration]
>      471 | static int is_first_zpdesc(struct zpdesc *zpdesc)
>          |            ^~~~~~~~~~~~~~~
>    1 warning generated.

I am not sure why the robot thinks that this change introduced this
warning, I think it has been present since patch 2 of this series.

The warning occurs when CONFIG_DEBUG_VM is disabled because
is_first_zpdesc() is used with VM_BUG_ON_PAGE, which ultimately
evaluates to BUILD_BUG_ON_INVALID() / sizeof(), so is_first_zpdesc() is
only used in a compile time context for this configuration. Perhaps this
can just be marked as __maybe_unused?

Cheers,
Nathan
diff mbox series

Patch

diff --git a/mm/zpdesc.h b/mm/zpdesc.h
index 6de3c5d095bd..296cb1ff944b 100644
--- a/mm/zpdesc.h
+++ b/mm/zpdesc.h
@@ -15,6 +15,8 @@ 
  * @next:		Next zpdesc in a zspage in zsmalloc zpool
  * @handle:		For huge zspage in zsmalloc zpool
  * @zspage:		Pointer to zspage in zsmalloc
+ * @first_obj_offset:	First object offset in zsmalloc zpool
+ * @_refcount:		Indirectly use by page migration
  * @memcg_data:		Memory Control Group data.
  *
  * This struct overlays struct page for now. Do not modify without a good
@@ -31,7 +33,8 @@  struct zpdesc {
 		unsigned long handle;
 	};
 	struct zspage *zspage;
-	unsigned long _zp_pad_1;
+	unsigned int first_obj_offset;
+	atomic_t _refcount;
 #ifdef CONFIG_SLAB_OBJ_EXT
 	unsigned long memcg_data;
 #endif
@@ -45,6 +48,7 @@  ZPDESC_MATCH(mapping, mops);
 ZPDESC_MATCH(index, next);
 ZPDESC_MATCH(index, handle);
 ZPDESC_MATCH(private, zspage);
+ZPDESC_MATCH(page_type, first_obj_offset);
 ZPDESC_MATCH(memcg_data, memcg_data);
 #undef ZPDESC_MATCH
 static_assert(sizeof(struct zpdesc) <= sizeof(struct page));
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 8b713ac03902..0493f953fcb5 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -494,26 +494,26 @@  static struct zpdesc *get_first_zpdesc(struct zspage *zspage)
 
 #define FIRST_OBJ_PAGE_TYPE_MASK	0xffff
 
-static inline void reset_first_obj_offset(struct page *page)
+static inline void reset_first_obj_offset(struct zpdesc *zpdesc)
 {
-	VM_WARN_ON_ONCE(!PageZsmalloc(page));
-	page->page_type |= FIRST_OBJ_PAGE_TYPE_MASK;
+	VM_WARN_ON_ONCE(!PageZsmalloc(zpdesc_page(zpdesc)));
+	zpdesc->first_obj_offset |= FIRST_OBJ_PAGE_TYPE_MASK;
 }
 
-static inline unsigned int get_first_obj_offset(struct page *page)
+static inline unsigned int get_first_obj_offset(struct zpdesc *zpdesc)
 {
-	VM_WARN_ON_ONCE(!PageZsmalloc(page));
-	return page->page_type & FIRST_OBJ_PAGE_TYPE_MASK;
+	VM_WARN_ON_ONCE(!PageZsmalloc(zpdesc_page(zpdesc)));
+	return zpdesc->first_obj_offset & FIRST_OBJ_PAGE_TYPE_MASK;
 }
 
-static inline void set_first_obj_offset(struct page *page, unsigned int offset)
+static inline void set_first_obj_offset(struct zpdesc *zpdesc, unsigned int offset)
 {
 	/* With 16 bit available, we can support offsets into 64 KiB pages. */
 	BUILD_BUG_ON(PAGE_SIZE > SZ_64K);
-	VM_WARN_ON_ONCE(!PageZsmalloc(page));
+	VM_WARN_ON_ONCE(!PageZsmalloc(zpdesc_page(zpdesc)));
 	VM_WARN_ON_ONCE(offset & ~FIRST_OBJ_PAGE_TYPE_MASK);
-	page->page_type &= ~FIRST_OBJ_PAGE_TYPE_MASK;
-	page->page_type |= offset & FIRST_OBJ_PAGE_TYPE_MASK;
+	zpdesc->first_obj_offset &= ~FIRST_OBJ_PAGE_TYPE_MASK;
+	zpdesc->first_obj_offset |= offset & FIRST_OBJ_PAGE_TYPE_MASK;
 }
 
 static inline unsigned int get_freeobj(struct zspage *zspage)
@@ -850,7 +850,7 @@  static void reset_zpdesc(struct zpdesc *zpdesc)
 	ClearPagePrivate(page);
 	zpdesc->zspage = NULL;
 	zpdesc->next = NULL;
-	reset_first_obj_offset(page);
+	reset_first_obj_offset(zpdesc);
 	__ClearPageZsmalloc(page);
 }
 
@@ -934,7 +934,7 @@  static void init_zspage(struct size_class *class, struct zspage *zspage)
 		struct link_free *link;
 		void *vaddr;
 
-		set_first_obj_offset(zpdesc_page(zpdesc), off);
+		set_first_obj_offset(zpdesc, off);
 
 		vaddr = zpdesc_kmap_atomic(zpdesc);
 		link = (struct link_free *)vaddr + off / sizeof(*link);
@@ -1589,7 +1589,7 @@  static unsigned long find_alloced_obj(struct size_class *class,
 	unsigned long handle = 0;
 	void *addr = zpdesc_kmap_atomic(zpdesc);
 
-	offset = get_first_obj_offset(zpdesc_page(zpdesc));
+	offset = get_first_obj_offset(zpdesc);
 	offset += class->size * index;
 
 	while (offset < PAGE_SIZE) {
@@ -1784,8 +1784,8 @@  static void replace_sub_page(struct size_class *class, struct zspage *zspage,
 	} while ((zpdesc = get_next_zpdesc(zpdesc)) != NULL);
 
 	create_page_chain(class, zspage, zpdescs);
-	first_obj_offset = get_first_obj_offset(zpdesc_page(oldzpdesc));
-	set_first_obj_offset(zpdesc_page(newzpdesc), first_obj_offset);
+	first_obj_offset = get_first_obj_offset(oldzpdesc);
+	set_first_obj_offset(newzpdesc, first_obj_offset);
 	if (unlikely(ZsHugePage(zspage)))
 		newzpdesc->handle = oldzpdesc->handle;
 	__zpdesc_set_movable(newzpdesc, &zsmalloc_mops);
@@ -1840,7 +1840,7 @@  static int zs_page_migrate(struct page *newpage, struct page *page,
 	/* the migrate_write_lock protects zpage access via zs_map_object */
 	migrate_write_lock(zspage);
 
-	offset = get_first_obj_offset(zpdesc_page(zpdesc));
+	offset = get_first_obj_offset(zpdesc);
 	s_addr = zpdesc_kmap_atomic(zpdesc);
 
 	/*