mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool

PATCH Superseded [email protected] 3 participants 24 messages Jul 8, 2024 – Jul 15, 2024

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2024-07-08 06:28 UTC #0 lore raw

v3 cover mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool

From: Alex Shi (Tencent) <[email protected]>

According to Metthew's plan, the page descriptor will be replace by a 8 bytes mem_desc on destination purpose.
https://lore.kernel.org/lkml/[email protected]/

Here is a implement on zsmalloc to replace page descriptor by 'zpdesc', which is still overlay on struct page now. but it's a step move forward above destination.

To name the struct zpdesc instead of zsdesc, since there are still 3 zpools under zswap: zbud, z3fold, zsmalloc for now(z3fold maybe removed soon), and we could easyly extend it to other zswap.zpool in needs.

For all zswap.zpools, they are all using single page since often used under memory pressure. So the conversion via folio series helper is better than page's for compound_head check saving.

For now, all zpools are using some page struct members, like page.flags for PG_private/PG_locked. and list_head lru, page.mapping for page migration.

This patachset does not increase the descriptor size nor introduce any functional changes, and could save about 122Kbytes zsmalloc.o size.

Thanks
Alex

---
v3->v2:
- Fix LKP reported build issue
- Update the Usage of struct zpdesc fields.
- Rebase onto latest mm-unstable commit 2073cda629a4

v1->v2:
- Take Yosry and Yoo's suggestion to add more members in zpdesc,
- Rebase on latest mm-unstable commit 31334cf98dbd
---

Alex Shi (Tencent) (9):
mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool mm/zsmalloc: use zpdesc in trylock_zspage/lock_zspage mm/zsmalloc: convert create_page_chain() and its users to use zpdesc mm/zsmalloc: rename reset_page to reset_zpdesc and use zpdesc in it mm/zsmalloc: convert SetZsPageMovable and remove unused funcs mm/zsmalloc: convert get/set_first_obj_offset() to take zpdesc mm/zsmalloc: introduce __zpdesc_clear_movable mm/zsmalloc: introduce __zpdesc_clear_zsmalloc mm/zsmalloc: introduce __zpdesc_set_zsmalloc()

Hyeonggon Yoo (11):
mm/zsmalloc: convert __zs_map_object/__zs_unmap_object to use zpdesc mm/zsmalloc: add and use pfn/zpdesc seeking funcs mm/zsmalloc: convert obj_malloc() to use zpdesc mm/zsmalloc: convert obj_allocated() and related helpers to use zpdesc mm/zsmalloc: convert init_zspage() to use zpdesc mm/zsmalloc: convert obj_to_page() and zs_free() to use zpdesc mm/zsmalloc: add zpdesc_is_isolated/zpdesc_zone helper for
zs_page_migrate
mm/zsmalloc: convert __free_zspage() to use zdsesc mm/zsmalloc: convert location_to_obj() to take zpdesc mm/zsmalloc: convert migrate_zspage() to use zpdesc mm/zsmalloc: convert get_zspage() to take zpdesc

 mm/zpdesc.h   | 146 ++++++++++++++++
 mm/zsmalloc.c | 460 +++++++++++++++++++++++++++-----------------------
 2 files changed, 398 insertions(+), 208 deletions(-)
 create mode 100644 mm/zpdesc.h

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:28 UTC #1 lore raw

PATCH v3 1/20 mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool

From: Alex Shi (Tencent) <[email protected]>

The 1st patch introduces new memory decriptor zpdesc and rename zspage.first_page to zspage.first_zpdesc, no functional change.

We removed PG_owner_priv_1 since it was moved to zspage after commit a41ec880aa7b ("zsmalloc: move huge compressed obj from page to zspage").

And keep the memcg_data member, since as Yosry pointed out:
"When the pages are freed, put_page() -> folio_put() -> __folio_put() will call mem_cgroup_uncharge(). The latter will call folio_memcg() (which reads folio->memcg_data) to figure out if uncharging needs to be done.

There are also other similar code paths that will check folio->memcg_data. It is currently expected to be present for all folios. So until we have custom code paths per-folio type for allocation/freeing/etc, we need to keep folio->memcg_data present and properly initialized."

Originally-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
 mm/zsmalloc.c | 21 ++++++++--------
 2 files changed, 76 insertions(+), 11 deletions(-)
 create mode 100644 mm/zpdesc.h

mm/zpdesc.h new file +66 -0

new file mode 100644
index 000000000000..2dbef231f616
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* zpdesc.h: zswap.zpool memory descriptor
+ *
+ * Written by Alex Shi (Tencent) <[email protected]>
+ *	      Hyeonggon Yoo <[email protected]>
+ */
+#ifndef __MM_ZPDESC_H__
+#define __MM_ZPDESC_H__
+
+/*
+ * struct zpdesc -	Memory descriptor for zpool memory, now is for zsmalloc
+ * @flags:		Page flags, PG_private: identifies the first component page
+ * @lru:		Indirectly used by page migration
+ * @mops:		Used by page migration
+ * @next:		Next zpdesc in a zspage in zsmalloc zpool
+ * @handle:		For huge zspage in zsmalloc zpool
+ * @zspage:		Pointer to zspage in zsmalloc
+ * @memcg_data:		Memory Control Group data.
+ *
+ * This struct overlays struct page for now. Do not modify without a good
+ * understanding of the issues.
+ */
+struct zpdesc {
+	unsigned long flags;
+	struct list_head lru;
+	struct movable_operations *mops;
+	union {
+		/* Next zpdescs in a zspage in zsmalloc zpool */
+		struct zpdesc *next;
+		/* For huge zspage in zsmalloc zpool */
+		unsigned long handle;
+	};
+	struct zspage *zspage;
+	unsigned long _zp_pad_1;
+#ifdef CONFIG_MEMCG
+	unsigned long memcg_data;
+#endif
+};
+#define ZPDESC_MATCH(pg, zp) \
+	static_assert(offsetof(struct page, pg) == offsetof(struct zpdesc, zp))
+
+ZPDESC_MATCH(flags, flags);
+ZPDESC_MATCH(lru, lru);
+ZPDESC_MATCH(mapping, mops);
+ZPDESC_MATCH(index, next);
+ZPDESC_MATCH(index, handle);
+ZPDESC_MATCH(private, zspage);
+#ifdef CONFIG_MEMCG
+ZPDESC_MATCH(memcg_data, memcg_data);
+#endif
+#undef ZPDESC_MATCH
+static_assert(sizeof(struct zpdesc) <= sizeof(struct page));
+
+#define zpdesc_page(zp)			(_Generic((zp),			\
+	const struct zpdesc *:		(const struct page *)(zp),	\
+	struct zpdesc *:		(struct page *)(zp)))
+
+#define zpdesc_folio(zp)		(_Generic((zp),			\
+	const struct zpdesc *:		(const struct folio *)(zp),	\
+	struct zpdesc *:		(struct folio *)(zp)))
+
+#define page_zpdesc(p)			(_Generic((p),			\
+	const struct page *:		(const struct zpdesc *)(p),	\
+	struct page *:			(struct zpdesc *)(p)))
+
+#endif

mm/zsmalloc.c +10 ~~-11~~

index 5d6581ab7c07..a532851025f9 100644
@@ -13,20 +13,18 @@
 
 /*
  * Following is how we use various fields and flags of underlying
- * struct page(s) to form a zspage.
+ * struct zpdesc(page) to form a zspage.
  *
- * Usage of struct page fields:
- *	page->private: points to zspage
- *	page->index: links together all component pages of a zspage
+ * Usage of struct zpdesc fields:
+ *	zpdesc->zspage: points to zspage
+ *	zpdesc->next: links together all component pages of a zspage
  *		For the huge page, this is always 0, so we use this field
  *		to store handle.
  *	page->page_type: PG_zsmalloc, lower 16 bit locate the first object
  *		offset in a subpage of a zspage
  *
- * Usage of struct page flags:
+ * Usage of struct zpdesc(page) flags:
  *	PG_private: identifies the first component page
- *	PG_owner_priv_1: identifies the huge component page
- *
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

@@ -64,6 +62,7 @@
 #include <linux/pagemap.h>
 #include <linux/fs.h>
 #include <linux/local_lock.h>
+#include "zpdesc.h"
 
 #define ZSPAGE_MAGIC	0x58

@@ -253,7 +252,7 @@ struct zspage {
 	};
 	unsigned int inuse;
 	unsigned int freeobj;
-	struct page *first_page;
+	struct zpdesc *first_zpdesc;
 	struct list_head list; /* fullness list */
 	struct zs_pool *pool;
 	rwlock_t lock;

@@ -448,7 +447,7 @@ static inline void mod_zspage_inuse(struct zspage *zspage, int val)
 
 static inline struct page *get_first_page(struct zspage *zspage)
 {
-	struct page *first_page = zspage->first_page;
+	struct page *first_page = zpdesc_page(zspage->first_zpdesc);
 
 	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
 	return first_page;

@@ -948,7 +947,7 @@ static void create_page_chain(struct size_class *class, struct zspage *zspage,
 		set_page_private(page, (unsigned long)zspage);
 		page->index = 0;
 		if (i == 0) {
-			zspage->first_page = page;
+			zspage->first_zpdesc = page_zpdesc(page);
 			SetPagePrivate(page);
 			if (unlikely(class->objs_per_zspage == 1 &&
 					class->pages_per_zspage == 1))

@@ -1324,7 +1323,7 @@ static unsigned long obj_malloc(struct zs_pool *pool,
 		link->handle = handle | OBJ_ALLOCATED_TAG;
 	else
 		/* record handle to page->index */
-		zspage->first_page->index = handle | OBJ_ALLOCATED_TAG;
+		zspage->first_zpdesc->handle = handle | OBJ_ALLOCATED_TAG;
 
 	kunmap_atomic(vaddr);
 	mod_zspage_inuse(zspage, 1);

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:28 UTC #2 lore raw

PATCH v3 2/20 mm/zsmalloc: use zpdesc in trylock_zspage/lock_zspage

In reply to [email protected]

From: Alex Shi (Tencent) <[email protected]>

To use zpdesc in trylock_zspage/lock_zspage funcs, we add couple of helpers:
zpdesc_lock/zpdesc_unlock/zpdesc_trylock/zpdesc_wait_locked and zpdesc_get/zpdesc_put for this purpose.

Here we use the folio series func in guts for 2 reasons, one zswap.zpool only get single page, and use folio could save some compound_head checking; two, folio_put could bypass devmap checking that we don't need.

Originally-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   | 30 ++++++++++++++++++++++++
 mm/zsmalloc.c | 64 ++++++++++++++++++++++++++++++++++-----------------
 2 files changed, 73 insertions(+), 21 deletions(-)

mm/zpdesc.h +30 -0

index 2dbef231f616..3b04197cec9d 100644
@@ -63,4 +63,34 @@ static_assert(sizeof(struct zpdesc) <= sizeof(struct page));
 	const struct page *:		(const struct zpdesc *)(p),	\
 	struct page *:			(struct zpdesc *)(p)))
 
+static inline void zpdesc_lock(struct zpdesc *zpdesc)
+{
+	folio_lock(zpdesc_folio(zpdesc));
+}
+
+static inline bool zpdesc_trylock(struct zpdesc *zpdesc)
+{
+	return folio_trylock(zpdesc_folio(zpdesc));
+}
+
+static inline void zpdesc_unlock(struct zpdesc *zpdesc)
+{
+	folio_unlock(zpdesc_folio(zpdesc));
+}
+
+static inline void zpdesc_wait_locked(struct zpdesc *zpdesc)
+{
+	folio_wait_locked(zpdesc_folio(zpdesc));
+}
+
+static inline void zpdesc_get(struct zpdesc *zpdesc)
+{
+	folio_get(zpdesc_folio(zpdesc));
+}
+
+static inline void zpdesc_put(struct zpdesc *zpdesc)
+{
+	folio_put(zpdesc_folio(zpdesc));
+}
+
 #endif

mm/zsmalloc.c +43 ~~-21~~

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Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:28 UTC #3 lore raw

PATCH v3 3/20 mm/zsmalloc: convert __zs_map_object/__zs_unmap_object to use zpdesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

These two functions take pointer to an array of struct page. Introduce zpdesc_kmap_atomic() and make __zs_{map,unmap}_object() take pointer to an array of zpdesc instead of page.

Add silly type casting when calling them. Casting will be removed late.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

mm/zsmalloc.c +13 -8

index 243677a9c6d2..68a39c233d34 100644
@@ -243,6 +243,11 @@ struct zs_pool {
 	atomic_t compaction_in_progress;
 };
 
+static inline void *zpdesc_kmap_atomic(struct zpdesc *zpdesc)
+{
+	return kmap_atomic(zpdesc_page(zpdesc));
+}
+
 struct zspage {
 	struct {
 		unsigned int huge:HUGE_BITS;

@@ -1061,7 +1066,7 @@ static inline void __zs_cpu_down(struct mapping_area *area)
 }
 
 static void *__zs_map_object(struct mapping_area *area,
-			struct page *pages[2], int off, int size)
+			struct zpdesc *zpdescs[2], int off, int size)
 {
 	int sizes[2];
 	void *addr;

@@ -1078,10 +1083,10 @@ static void *__zs_map_object(struct mapping_area *area,
 	sizes[1] = size - sizes[0];
 
 	/* copy object to per-cpu buffer */
-	addr = kmap_atomic(pages[0]);
+	addr = zpdesc_kmap_atomic(zpdescs[0]);
 	memcpy(buf, addr + off, sizes[0]);
 	kunmap_atomic(addr);
-	addr = kmap_atomic(pages[1]);
+	addr = zpdesc_kmap_atomic(zpdescs[1]);
 	memcpy(buf + sizes[0], addr, sizes[1]);
 	kunmap_atomic(addr);
 out:

@@ -1089,7 +1094,7 @@ static void *__zs_map_object(struct mapping_area *area,
 }
 
 static void __zs_unmap_object(struct mapping_area *area,
-			struct page *pages[2], int off, int size)
+			struct zpdesc *zpdescs[2], int off, int size)
 {
 	int sizes[2];
 	void *addr;

@@ -1108,10 +1113,10 @@ static void __zs_unmap_object(struct mapping_area *area,
 	sizes[1] = size - sizes[0];
 
 	/* copy per-cpu buffer to object */
-	addr = kmap_atomic(pages[0]);
+	addr = zpdesc_kmap_atomic(zpdescs[0]);
 	memcpy(addr + off, buf, sizes[0]);
 	kunmap_atomic(addr);
-	addr = kmap_atomic(pages[1]);
+	addr = zpdesc_kmap_atomic(zpdescs[1]);
 	memcpy(addr, buf + sizes[0], sizes[1]);
 	kunmap_atomic(addr);

@@ -1252,7 +1257,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
 	pages[1] = get_next_page(page);
 	BUG_ON(!pages[1]);
 
-	ret = __zs_map_object(area, pages, off, class->size);
+	ret = __zs_map_object(area, (struct zpdesc **)pages, off, class->size);
 out:
 	if (likely(!ZsHugePage(zspage)))
 		ret += ZS_HANDLE_SIZE;

@@ -1287,7 +1292,7 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
 		pages[1] = get_next_page(page);
 		BUG_ON(!pages[1]);
 
-		__zs_unmap_object(area, pages, off, class->size);
+		__zs_unmap_object(area, (struct zpdesc **)pages, off, class->size);
 	}
 	local_unlock(&zs_map_area.lock);

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:28 UTC #4 lore raw

PATCH v3 4/20 mm/zsmalloc: add and use pfn/zpdesc seeking funcs

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

Add pfn_zpdesc conversion, convert obj_to_location() to take zpdesc and also convert its users to use zpdesc.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   |  9 +++++++
 mm/zsmalloc.c | 75 ++++++++++++++++++++++++++-------------------------
 2 files changed, 47 insertions(+), 37 deletions(-)

mm/zpdesc.h +9 -0

index 3b04197cec9d..79ec40b03956 100644
@@ -93,4 +93,13 @@ static inline void zpdesc_put(struct zpdesc *zpdesc)
 	folio_put(zpdesc_folio(zpdesc));
 }
 
+static inline unsigned long zpdesc_pfn(struct zpdesc *zpdesc)
+{
+	return page_to_pfn(zpdesc_page(zpdesc));
+}
+
+static inline struct zpdesc *pfn_zpdesc(unsigned long pfn)
+{
+	return page_zpdesc(pfn_to_page(pfn));
+}
 #endif

mm/zsmalloc.c +38 ~~-37~~

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Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #5 lore raw

PATCH v3 5/20 mm/zsmalloc: convert obj_malloc() to use zpdesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

Use get_first_zpdesc/get_next_zpdesc to replace get_first_page/get_next_page. no functional change.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

mm/zsmalloc.c +8 -8

index 149fe2b332cb..bbc165cb587d 100644
@@ -1322,12 +1322,12 @@ EXPORT_SYMBOL_GPL(zs_huge_class_size);
 static unsigned long obj_malloc(struct zs_pool *pool,
 				struct zspage *zspage, unsigned long handle)
 {
-	int i, nr_page, offset;
+	int i, nr_zpdesc, offset;
 	unsigned long obj;
 	struct link_free *link;
 	struct size_class *class;
 
-	struct page *m_page;
+	struct zpdesc *m_zpdesc;
 	unsigned long m_offset;
 	void *vaddr;

@@ -1335,14 +1335,14 @@ static unsigned long obj_malloc(struct zs_pool *pool,
 	obj = get_freeobj(zspage);
 
 	offset = obj * class->size;
-	nr_page = offset >> PAGE_SHIFT;
+	nr_zpdesc = offset >> PAGE_SHIFT;
 	m_offset = offset_in_page(offset);
-	m_page = get_first_page(zspage);
+	m_zpdesc = get_first_zpdesc(zspage);
 
-	for (i = 0; i < nr_page; i++)
-		m_page = get_next_page(m_page);
+	for (i = 0; i < nr_zpdesc; i++)
+		m_zpdesc = get_next_zpdesc(m_zpdesc);
 
-	vaddr = kmap_atomic(m_page);
+	vaddr = zpdesc_kmap_atomic(m_zpdesc);
 	link = (struct link_free *)vaddr + m_offset / sizeof(*link);
 	set_freeobj(zspage, link->next >> OBJ_TAG_BITS);
 	if (likely(!ZsHugePage(zspage)))

@@ -1355,7 +1355,7 @@ static unsigned long obj_malloc(struct zs_pool *pool,
 	kunmap_atomic(vaddr);
 	mod_zspage_inuse(zspage, 1);
 
-	obj = location_to_obj(m_page, obj);
+	obj = location_to_obj(zpdesc_page(m_zpdesc), obj);
 	record_obj(handle, obj);
 
 	return obj;

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #6 lore raw

PATCH v3 6/20 mm/zsmalloc: convert create_page_chain() and its users to use zpdesc

In reply to [email protected]

From: Alex Shi (Tencent) <[email protected]>

Introduce a few helper functions for conversion to convert create_page_chain() to use zpdesc, then use zpdesc in replace_sub_page() too.

Originally-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   |   6 +++
 mm/zsmalloc.c | 115 +++++++++++++++++++++++++++++++++-----------------
 2 files changed, 82 insertions(+), 39 deletions(-)

mm/zpdesc.h +6 -0

index 79ec40b03956..2293453f5d57 100644
@@ -102,4 +102,10 @@ static inline struct zpdesc *pfn_zpdesc(unsigned long pfn)
 {
 	return page_zpdesc(pfn_to_page(pfn));
 }
+
+static inline void __zpdesc_set_movable(struct zpdesc *zpdesc,
+					const struct movable_operations *mops)
+{
+	__SetPageMovable(zpdesc_page(zpdesc), mops);
+}
 #endif

mm/zsmalloc.c +76 ~~-39~~

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Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #7 lore raw

PATCH v3 7/20 mm/zsmalloc: convert obj_allocated() and related helpers to use zpdesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

Convert obj_allocated(), and related helpers to take zpdesc. Also make its callers to cast (struct page *) to (struct zpdesc *) when calling them. The users will be converted gradually as there are many.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

mm/zsmalloc.c +10 ~~-10~~

index a8f390beeab8..29b9fa5baa46 100644
@@ -845,15 +845,15 @@ static unsigned long handle_to_obj(unsigned long handle)
 	return *(unsigned long *)handle;
 }
 
-static inline bool obj_allocated(struct page *page, void *obj,
+static inline bool obj_allocated(struct zpdesc *zpdesc, void *obj,
 				 unsigned long *phandle)
 {
 	unsigned long handle;
-	struct zspage *zspage = get_zspage(page);
+	struct zspage *zspage = get_zspage(zpdesc_page(zpdesc));
 
 	if (unlikely(ZsHugePage(zspage))) {
-		VM_BUG_ON_PAGE(!is_first_page(page), page);
-		handle = page->index;
+		VM_BUG_ON_PAGE(!is_first_zpdesc(zpdesc), zpdesc_page(zpdesc));
+		handle = zpdesc->handle;
 	} else
 		handle = *(unsigned long *)obj;

@@ -1603,18 +1603,18 @@ static void zs_object_copy(struct size_class *class, unsigned long dst,
  * return handle.
  */
 static unsigned long find_alloced_obj(struct size_class *class,
-				      struct page *page, int *obj_idx)
+				      struct zpdesc *zpdesc, int *obj_idx)
 {
 	unsigned int offset;
 	int index = *obj_idx;
 	unsigned long handle = 0;
-	void *addr = kmap_atomic(page);
+	void *addr = zpdesc_kmap_atomic(zpdesc);
 
-	offset = get_first_obj_offset(page);
+	offset = get_first_obj_offset(zpdesc_page(zpdesc));
 	offset += class->size * index;
 
 	while (offset < PAGE_SIZE) {
-		if (obj_allocated(page, addr + offset, &handle))
+		if (obj_allocated(zpdesc, addr + offset, &handle))
 			break;
 
 		offset += class->size;

@@ -1638,7 +1638,7 @@ static void migrate_zspage(struct zs_pool *pool, struct zspage *src_zspage,
 	struct size_class *class = pool->size_class[src_zspage->class];
 
 	while (1) {
-		handle = find_alloced_obj(class, s_page, &obj_idx);
+		handle = find_alloced_obj(class, page_zpdesc(s_page), &obj_idx);
 		if (!handle) {
 			s_page = get_next_page(s_page);
 			if (!s_page)

@@ -1871,7 +1871,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 
 	for (addr = s_addr + offset; addr < s_addr + PAGE_SIZE;
 					addr += class->size) {
-		if (obj_allocated(page, addr, &handle)) {
+		if (obj_allocated(page_zpdesc(page), addr, &handle)) {
 
 			old_obj = handle_to_obj(handle);
 			obj_to_location(old_obj, &dummy, &obj_idx);

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #8 lore raw

PATCH v3 8/20 mm/zsmalloc: convert init_zspage() to use zpdesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

Replace get_first/next_page func series and kmap_atomic to new helper, no functional change.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

mm/zsmalloc.c +8 -8

index 29b9fa5baa46..d3558f3f8bc3 100644
@@ -948,16 +948,16 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
 {
 	unsigned int freeobj = 1;
 	unsigned long off = 0;
-	struct page *page = get_first_page(zspage);
+	struct zpdesc *zpdesc = get_first_zpdesc(zspage);
 
-	while (page) {
-		struct page *next_page;
+	while (zpdesc) {
+		struct zpdesc *next_zpdesc;
 		struct link_free *link;
 		void *vaddr;
 
-		set_first_obj_offset(page, off);
+		set_first_obj_offset(zpdesc_page(zpdesc), off);
 
-		vaddr = kmap_atomic(page);
+		vaddr = zpdesc_kmap_atomic(zpdesc);
 		link = (struct link_free *)vaddr + off / sizeof(*link);
 
 		while ((off += class->size) < PAGE_SIZE) {

@@ -970,8 +970,8 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
 		 * page, which must point to the first object on the next
 		 * page (if present)
 		 */
-		next_page = get_next_page(page);
-		if (next_page) {
+		next_zpdesc = get_next_zpdesc(zpdesc);
+		if (next_zpdesc) {
 			link->next = freeobj++ << OBJ_TAG_BITS;
 		} else {
 			/*

@@ -981,7 +981,7 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
 			link->next = -1UL << OBJ_TAG_BITS;
 		}
 		kunmap_atomic(vaddr);
-		page = next_page;
+		zpdesc = next_zpdesc;
 		off %= PAGE_SIZE;
 	}

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #9 lore raw

PATCH v3 9/20 mm/zsmalloc: convert obj_to_page() and zs_free() to use zpdesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

Rename obj_to_page() to obj_to_zpdesc() and also convert it and its user zs_free() to use zpdesc.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

mm/zsmalloc.c +5 -5

index d3558f3f8bc3..7aa4a4acaec9 100644
@@ -820,9 +820,9 @@ static void obj_to_location(unsigned long obj, struct zpdesc **zpdesc,
 	*obj_idx = (obj & OBJ_INDEX_MASK);
 }
 
-static void obj_to_page(unsigned long obj, struct page **page)
+static void obj_to_zpdesc(unsigned long obj, struct zpdesc **zpdesc)
 {
-	*page = pfn_to_page(obj >> OBJ_INDEX_BITS);
+	*zpdesc = pfn_zpdesc(obj >> OBJ_INDEX_BITS);
 }
 
 /**

@@ -1496,7 +1496,7 @@ static void obj_free(int class_size, unsigned long obj)
 void zs_free(struct zs_pool *pool, unsigned long handle)
 {
 	struct zspage *zspage;
-	struct page *f_page;
+	struct zpdesc *f_zpdesc;
 	unsigned long obj;
 	struct size_class *class;
 	int fullness;

@@ -1510,8 +1510,8 @@ void zs_free(struct zs_pool *pool, unsigned long handle)
 	 */
 	read_lock(&pool->migrate_lock);
 	obj = handle_to_obj(handle);
-	obj_to_page(obj, &f_page);
-	zspage = get_zspage(f_page);
+	obj_to_zpdesc(obj, &f_zpdesc);
+	zspage = get_zspage(zpdesc_page(f_zpdesc));
 	class = zspage_class(pool, zspage);
 	spin_lock(&class->lock);
 	read_unlock(&pool->migrate_lock);

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #10 lore raw

PATCH v3 10/20 mm/zsmalloc: add zpdesc_is_isolated/zpdesc_zone helper for zs_page_migrate

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

To convert page to zpdesc in zs_page_migrate(), we added zpdesc_is_isolated/zpdesc_zone helpers. No functional change.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   | 11 +++++++++++
 mm/zsmalloc.c | 30 ++++++++++++++++--------------
 2 files changed, 27 insertions(+), 14 deletions(-)

mm/zpdesc.h +11 -0

index 2293453f5d57..ad04c8337cae 100644
@@ -108,4 +108,15 @@ static inline void __zpdesc_set_movable(struct zpdesc *zpdesc,
 {
 	__SetPageMovable(zpdesc_page(zpdesc), mops);
 }
+
+static inline bool zpdesc_is_isolated(struct zpdesc *zpdesc)
+{
+	return PageIsolated(zpdesc_page(zpdesc));
+}
+
+static inline struct zone *zpdesc_zone(struct zpdesc *zpdesc)
+{
+	return page_zone(zpdesc_page(zpdesc));
+}
+
 #endif

mm/zsmalloc.c +16 ~~-14~~

index 7aa4a4acaec9..9bc9b14187ed 100644
@@ -1830,19 +1830,21 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	struct size_class *class;
 	struct zspage *zspage;
 	struct zpdesc *dummy;
+	struct zpdesc *newzpdesc = page_zpdesc(newpage);
+	struct zpdesc *zpdesc = page_zpdesc(page);
 	void *s_addr, *d_addr, *addr;
 	unsigned int offset;
 	unsigned long handle;
 	unsigned long old_obj, new_obj;
 	unsigned int obj_idx;
 
-	VM_BUG_ON_PAGE(!PageIsolated(page), page);
+	VM_BUG_ON_PAGE(!zpdesc_is_isolated(zpdesc), zpdesc_page(zpdesc));
 
 	/* We're committed, tell the world that this is a Zsmalloc page. */
-	__SetPageZsmalloc(newpage);
+	__SetPageZsmalloc(zpdesc_page(newzpdesc));
 
 	/* The page is locked, so this pointer must remain valid */
-	zspage = get_zspage(page);
+	zspage = get_zspage(zpdesc_page(zpdesc));
 	pool = zspage->pool;
 
 	/*

@@ -1859,30 +1861,30 @@ 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(page);
-	s_addr = kmap_atomic(page);
+	offset = get_first_obj_offset(zpdesc_page(zpdesc));
+	s_addr = zpdesc_kmap_atomic(zpdesc);
 
 	/*
 	 * Here, any user cannot access all objects in the zspage so let's move.
 	 */
-	d_addr = kmap_atomic(newpage);
+	d_addr = zpdesc_kmap_atomic(newzpdesc);
 	copy_page(d_addr, s_addr);
 	kunmap_atomic(d_addr);
 
 	for (addr = s_addr + offset; addr < s_addr + PAGE_SIZE;
 					addr += class->size) {
-		if (obj_allocated(page_zpdesc(page), addr, &handle)) {
+		if (obj_allocated(zpdesc, addr, &handle)) {
 
 			old_obj = handle_to_obj(handle);
 			obj_to_location(old_obj, &dummy, &obj_idx);
-			new_obj = (unsigned long)location_to_obj(newpage,
+			new_obj = (unsigned long)location_to_obj(zpdesc_page(newzpdesc),
 								obj_idx);
 			record_obj(handle, new_obj);
 		}
 	}
 	kunmap_atomic(s_addr);
 
-	replace_sub_page(class, zspage, page_zpdesc(newpage), page_zpdesc(page));
+	replace_sub_page(class, zspage, newzpdesc, zpdesc);
 	/*
 	 * Since we complete the data copy and set up new zspage structure,
 	 * it's okay to release migration_lock.

@@ -1891,14 +1893,14 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	spin_unlock(&class->lock);
 	migrate_write_unlock(zspage);
 
-	get_page(newpage);
-	if (page_zone(newpage) != page_zone(page)) {
-		dec_zone_page_state(page, NR_ZSPAGES);
-		inc_zone_page_state(newpage, NR_ZSPAGES);
+	zpdesc_get(newzpdesc);
+	if (zpdesc_zone(newzpdesc) != zpdesc_zone(zpdesc)) {
+		zpdesc_dec_zone_page_state(zpdesc);
+		zpdesc_inc_zone_page_state(newzpdesc);
 	}
 
 	reset_page(page);
-	put_page(page);
+	zpdesc_put(zpdesc);
 
 	return MIGRATEPAGE_SUCCESS;
 }

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #11 lore raw

PATCH v3 11/20 mm/zsmalloc: rename reset_page to reset_zpdesc and use zpdesc in it

In reply to [email protected]

From: Alex Shi (Tencent) <[email protected]>

zpdesc.zspage matches with page.private, zpdesc.next matches with page.index. They will be reset in reset_page() wich is called prior to free base pages of a zspage.
Use zpdesc to replace page struct and rename it to reset_zpdesc(), few page helper still left since they are used too widely.

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

mm/zsmalloc.c +7 -5

index 9bc9b14187ed..6d1971836391 100644
@@ -865,12 +865,14 @@ static inline bool obj_allocated(struct zpdesc *zpdesc, void *obj,
 	return true;
 }
 
-static void reset_page(struct page *page)
+static void reset_zpdesc(struct zpdesc *zpdesc)
 {
+	struct page *page = zpdesc_page(zpdesc);
+
 	__ClearPageMovable(page);
 	ClearPagePrivate(page);
-	set_page_private(page, 0);
-	page->index = 0;
+	zpdesc->zspage = NULL;
+	zpdesc->next = NULL;
 	reset_first_obj_offset(page);
 	__ClearPageZsmalloc(page);
 }

@@ -910,7 +912,7 @@ static void __free_zspage(struct zs_pool *pool, struct size_class *class,
 	do {
 		VM_BUG_ON_PAGE(!PageLocked(page), page);
 		next = get_next_page(page);
-		reset_page(page);
+		reset_zpdesc(page_zpdesc(page));
 		unlock_page(page);
 		dec_zone_page_state(page, NR_ZSPAGES);
 		put_page(page);

@@ -1899,7 +1901,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 		zpdesc_inc_zone_page_state(newzpdesc);
 	}
 
-	reset_page(page);
+	reset_zpdesc(zpdesc);
 	zpdesc_put(zpdesc);
 
 	return MIGRATEPAGE_SUCCESS;

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #12 lore raw

PATCH v3 12/20 mm/zsmalloc: convert __free_zspage() to use zdsesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

Introduce zpdesc_is_locked() and convert __free_zspage() to use zpdesc.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   |  4 ++++
 mm/zsmalloc.c | 20 ++++++++++----------
 2 files changed, 14 insertions(+), 10 deletions(-)

mm/zpdesc.h +4 -0

index ad04c8337cae..72c8c072b4c8 100644
@@ -119,4 +119,8 @@ static inline struct zone *zpdesc_zone(struct zpdesc *zpdesc)
 	return page_zone(zpdesc_page(zpdesc));
 }
 
+static inline bool zpdesc_is_locked(struct zpdesc *zpdesc)
+{
+	return PageLocked(zpdesc_page(zpdesc));
+}
 #endif

mm/zsmalloc.c +10 ~~-10~~

index 6d1971836391..68fdea7b6e0d 100644
@@ -901,23 +901,23 @@ static int trylock_zspage(struct zspage *zspage)
 static void __free_zspage(struct zs_pool *pool, struct size_class *class,
 				struct zspage *zspage)
 {
-	struct page *page, *next;
+	struct zpdesc *zpdesc, *next;
 
 	assert_spin_locked(&class->lock);
 
 	VM_BUG_ON(get_zspage_inuse(zspage));
 	VM_BUG_ON(zspage->fullness != ZS_INUSE_RATIO_0);
 
-	next = page = get_first_page(zspage);
+	next = zpdesc = get_first_zpdesc(zspage);
 	do {
-		VM_BUG_ON_PAGE(!PageLocked(page), page);
-		next = get_next_page(page);
-		reset_zpdesc(page_zpdesc(page));
-		unlock_page(page);
-		dec_zone_page_state(page, NR_ZSPAGES);
-		put_page(page);
-		page = next;
-	} while (page != NULL);
+		VM_BUG_ON_PAGE(!zpdesc_is_locked(zpdesc), zpdesc_page(zpdesc));
+		next = get_next_zpdesc(zpdesc);
+		reset_zpdesc(zpdesc);
+		zpdesc_unlock(zpdesc);
+		zpdesc_dec_zone_page_state(zpdesc);
+		zpdesc_put(zpdesc);
+		zpdesc = next;
+	} while (zpdesc != NULL);
 
 	cache_free_zspage(pool, zspage);

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #13 lore raw

PATCH v3 13/20 mm/zsmalloc: convert location_to_obj() to take zpdesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

As all users of location_to_obj() now use zpdesc, convert location_to_obj() to take zpdesc.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

mm/zsmalloc.c +6 -7

index 68fdea7b6e0d..e291c7319485 100644
@@ -826,15 +826,15 @@ static void obj_to_zpdesc(unsigned long obj, struct zpdesc **zpdesc)
 }
 
 /**
- * location_to_obj - get obj value encoded from (<page>, <obj_idx>)
- * @page: page object resides in zspage
+ * location_to_obj - get obj value encoded from (<zpdesc>, <obj_idx>)
+ * @zpdesc: zpdesc object resides in zspage
  * @obj_idx: object index
  */
-static unsigned long location_to_obj(struct page *page, unsigned int obj_idx)
+static unsigned long location_to_obj(struct zpdesc *zpdesc, unsigned int obj_idx)
 {
 	unsigned long obj;
 
-	obj = page_to_pfn(page) << OBJ_INDEX_BITS;
+	obj = zpdesc_pfn(zpdesc) << OBJ_INDEX_BITS;
 	obj |= obj_idx & OBJ_INDEX_MASK;
 
 	return obj;

@@ -1392,7 +1392,7 @@ static unsigned long obj_malloc(struct zs_pool *pool,
 	kunmap_atomic(vaddr);
 	mod_zspage_inuse(zspage, 1);
 
-	obj = location_to_obj(zpdesc_page(m_zpdesc), obj);
+	obj = location_to_obj(m_zpdesc, obj);
 	record_obj(handle, obj);
 
 	return obj;

@@ -1879,8 +1879,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 
 			old_obj = handle_to_obj(handle);
 			obj_to_location(old_obj, &dummy, &obj_idx);
-			new_obj = (unsigned long)location_to_obj(zpdesc_page(newzpdesc),
-								obj_idx);
+			new_obj = (unsigned long)location_to_obj(newzpdesc, obj_idx);
 			record_obj(handle, new_obj);
 		}
 	}

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #14 lore raw

PATCH v3 14/20 mm/zsmalloc: convert migrate_zspage() to use zpdesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

Use get_first_zpdesc/get_next_zpdesc to replace get_first/next_page. No functional change.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

mm/zsmalloc.c +4 -4

index e291c7319485..7d039b0c66db 100644
@@ -1636,14 +1636,14 @@ static void migrate_zspage(struct zs_pool *pool, struct zspage *src_zspage,
 	unsigned long used_obj, free_obj;
 	unsigned long handle;
 	int obj_idx = 0;
-	struct page *s_page = get_first_page(src_zspage);
+	struct zpdesc *s_zpdesc = get_first_zpdesc(src_zspage);
 	struct size_class *class = pool->size_class[src_zspage->class];
 
 	while (1) {
-		handle = find_alloced_obj(class, page_zpdesc(s_page), &obj_idx);
+		handle = find_alloced_obj(class, s_zpdesc, &obj_idx);
 		if (!handle) {
-			s_page = get_next_page(s_page);
-			if (!s_page)
+			s_zpdesc = get_next_zpdesc(s_zpdesc);
+			if (!s_zpdesc)
 				break;
 			obj_idx = 0;
 			continue;

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #15 lore raw

PATCH v3 15/20 mm/zsmalloc: convert get_zspage() to take zpdesc

In reply to [email protected]

From: Hyeonggon Yoo <[email protected]>

Now that all users except get_next_page() (which will be removed in later patch) use zpdesc, convert get_zspage() to take zpdesc instead of page.

Signed-off-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

mm/zsmalloc.c +10 ~~-10~~

index 7d039b0c66db..458ad696b473 100644
@@ -779,9 +779,9 @@ static int fix_fullness_group(struct size_class *class, struct zspage *zspage)
 	return newfg;
 }
 
-static struct zspage *get_zspage(struct page *page)
+static struct zspage *get_zspage(struct zpdesc *zpdesc)
 {
-	struct zspage *zspage = (struct zspage *)page_private(page);
+	struct zspage *zspage = zpdesc->zspage;
 
 	BUG_ON(zspage->magic != ZSPAGE_MAGIC);
 	return zspage;

@@ -789,7 +789,7 @@ static struct zspage *get_zspage(struct page *page)
 
 static struct page *get_next_page(struct page *page)
 {
-	struct zspage *zspage = get_zspage(page);
+	struct zspage *zspage = get_zspage(page_zpdesc(page));
 
 	if (unlikely(ZsHugePage(zspage)))
 		return NULL;

@@ -799,7 +799,7 @@ static struct page *get_next_page(struct page *page)
 
 static struct zpdesc *get_next_zpdesc(struct zpdesc *zpdesc)
 {
-	struct zspage *zspage = get_zspage(zpdesc_page(zpdesc));
+	struct zspage *zspage = get_zspage(zpdesc);
 
 	if (unlikely(ZsHugePage(zspage)))
 		return NULL;

@@ -849,7 +849,7 @@ static inline bool obj_allocated(struct zpdesc *zpdesc, void *obj,
 				 unsigned long *phandle)
 {
 	unsigned long handle;
-	struct zspage *zspage = get_zspage(zpdesc_page(zpdesc));
+	struct zspage *zspage = get_zspage(zpdesc);
 
 	if (unlikely(ZsHugePage(zspage))) {
 		VM_BUG_ON_PAGE(!is_first_zpdesc(zpdesc), zpdesc_page(zpdesc));

@@ -1265,7 +1265,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
 	read_lock(&pool->migrate_lock);
 	obj = handle_to_obj(handle);
 	obj_to_location(obj, &zpdesc, &obj_idx);
-	zspage = get_zspage(zpdesc_page(zpdesc));
+	zspage = get_zspage(zpdesc);
 
 	/*
 	 * migration cannot move any zpages in this zspage. Here, class->lock

@@ -1315,7 +1315,7 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
 
 	obj = handle_to_obj(handle);
 	obj_to_location(obj, &zpdesc, &obj_idx);
-	zspage = get_zspage(zpdesc_page(zpdesc));
+	zspage = get_zspage(zpdesc);
 	class = zspage_class(pool, zspage);
 	off = offset_in_page(class->size * obj_idx);

@@ -1479,7 +1479,7 @@ static void obj_free(int class_size, unsigned long obj)
 
 	obj_to_location(obj, &f_zpdesc, &f_objidx);
 	f_offset = offset_in_page(class_size * f_objidx);
-	zspage = get_zspage(zpdesc_page(f_zpdesc));
+	zspage = get_zspage(f_zpdesc);
 
 	vaddr = zpdesc_kmap_atomic(f_zpdesc);
 	link = (struct link_free *)(vaddr + f_offset);

@@ -1513,7 +1513,7 @@ void zs_free(struct zs_pool *pool, unsigned long handle)
 	read_lock(&pool->migrate_lock);
 	obj = handle_to_obj(handle);
 	obj_to_zpdesc(obj, &f_zpdesc);
-	zspage = get_zspage(zpdesc_page(f_zpdesc));
+	zspage = get_zspage(f_zpdesc);
 	class = zspage_class(pool, zspage);
 	spin_lock(&class->lock);
 	read_unlock(&pool->migrate_lock);

@@ -1846,7 +1846,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	__SetPageZsmalloc(zpdesc_page(newzpdesc));
 
 	/* The page is locked, so this pointer must remain valid */
-	zspage = get_zspage(zpdesc_page(zpdesc));
+	zspage = get_zspage(zpdesc);
 	pool = zspage->pool;
 
 	/*

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #16 lore raw

PATCH v3 16/20 mm/zsmalloc: convert SetZsPageMovable and remove unused funcs

In reply to [email protected]

From: Alex Shi (Tencent) <[email protected]>

Convert SetZsPageMovable() to use zpdesc, and then remove unused funcs:get_next_page/get_first_page/is_first_page.

Originally-by Hyeonggon Yoo <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 33 +++++----------------------------
 1 file changed, 5 insertions(+), 28 deletions(-)

mm/zsmalloc.c +5 ~~-28~~

index 458ad696b473..8b713ac03902 100644
@@ -468,11 +468,6 @@ static DEFINE_PER_CPU(struct mapping_area, zs_map_area) = {
 	.lock	= INIT_LOCAL_LOCK(lock),
 };
 
-static __maybe_unused int is_first_page(struct page *page)
-{
-	return PagePrivate(page);
-}
-
 static int is_first_zpdesc(struct zpdesc *zpdesc)
 {
 	return PagePrivate(zpdesc_page(zpdesc));

@@ -489,14 +484,6 @@ static inline void mod_zspage_inuse(struct zspage *zspage, int val)
 	zspage->inuse += val;
 }
 
-static inline struct page *get_first_page(struct zspage *zspage)
-{
-	struct page *first_page = zpdesc_page(zspage->first_zpdesc);
-
-	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
-	return first_page;
-}
-
 static struct zpdesc *get_first_zpdesc(struct zspage *zspage)
 {
 	struct zpdesc *first_zpdesc = zspage->first_zpdesc;

@@ -787,16 +774,6 @@ static struct zspage *get_zspage(struct zpdesc *zpdesc)
 	return zspage;
 }
 
-static struct page *get_next_page(struct page *page)
-{
-	struct zspage *zspage = get_zspage(page_zpdesc(page));
-
-	if (unlikely(ZsHugePage(zspage)))
-		return NULL;
-
-	return (struct page *)page->index;
-}
-
 static struct zpdesc *get_next_zpdesc(struct zpdesc *zpdesc)
 {
 	struct zspage *zspage = get_zspage(zpdesc);

@@ -1970,13 +1947,13 @@ static void init_deferred_free(struct zs_pool *pool)
 
 static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage)
 {
-	struct page *page = get_first_page(zspage);
+	struct zpdesc *zpdesc = get_first_zpdesc(zspage);
 
 	do {
-		WARN_ON(!trylock_page(page));
-		__SetPageMovable(page, &zsmalloc_mops);
-		unlock_page(page);
-	} while ((page = get_next_page(page)) != NULL);
+		WARN_ON(!zpdesc_trylock(zpdesc));
+		__zpdesc_set_movable(zpdesc, &zsmalloc_mops);
+		zpdesc_unlock(zpdesc);
+	} while ((zpdesc = get_next_zpdesc(zpdesc)) != NULL);
 }
 #else
 static inline void zs_flush_migration(struct zs_pool *pool) { }

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #17 lore raw

PATCH v3 17/20 mm/zsmalloc: convert get/set_first_obj_offset() to take zpdesc

In reply to [email protected]

From: Alex Shi (Tencent) <[email protected]>

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 <[email protected]>

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   |  7 ++++++-
 mm/zsmalloc.c | 36 ++++++++++++++++++------------------
 2 files changed, 24 insertions(+), 19 deletions(-)

mm/zpdesc.h +6 -1

index 72c8c072b4c8..f64e813f4847 100644
@@ -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_MEMCG
 	unsigned long memcg_data;
 #endif

@@ -45,6 +48,8 @@ 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(_refcount, _refcount);
 #ifdef CONFIG_MEMCG
 ZPDESC_MATCH(memcg_data, memcg_data);
 #endif

mm/zsmalloc.c +18 ~~-18~~

index 8b713ac03902..bb8b5f13a966 100644
@@ -20,8 +20,8 @@
  *	zpdesc->next: links together all component pages of a zspage
  *		For the huge page, this is always 0, so we use this field
  *		to store handle.
- *	page->page_type: PG_zsmalloc, lower 16 bit locate the first object
- *		offset in a subpage of a zspage
+ *	zpdesc->first_obj_offset: PG_zsmalloc, lower 16 bit locate the first
+ *		object offset in a subpage of a zspage
  *
  * Usage of struct zpdesc(page) flags:
  *	PG_private: identifies the first component page

@@ -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);
 
 	/*

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 07:37 UTC #18 lore raw

PATCH 1/1 mm/zsmalloc: fix build warning from lkp testing

From: "Alex Shi (Tencent)" <[email protected]>

LKP reported the following warning w/o CONFIG_DEBUG_VM:
mm/zsmalloc.c:471:12: warning: function 'is_first_zpdesc' is not needed and will not be emitted [-Wunneeded-internal-declaration]
To remove this warning, better to incline the function is_first_zpdesc

Reported-by kernel test robot <[email protected]>

Closes https://lore.kernel.org/oe-kbuild-all/[email protected]/ open here

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zsmalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

mm/zsmalloc.c +1 -1

index 7f8e02df4e3e..64e523ae71f8 100644
@@ -468,7 +468,7 @@ static DEFINE_PER_CPU(struct mapping_area, zs_map_area) = {
 	.lock	= INIT_LOCAL_LOCK(lock),
 };
 
-static int is_first_zpdesc(struct zpdesc *zpdesc)
+static inline bool is_first_zpdesc(struct zpdesc *zpdesc)
 {
 	return PagePrivate(zpdesc_page(zpdesc));
 }

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #19 lore raw

PATCH v3 18/20 mm/zsmalloc: introduce __zpdesc_clear_movable

In reply to [email protected]

From: Alex Shi (Tencent) <[email protected]>

Add a helper __zpdesc_clear_movable() for __ClearPageMovable(), and use it in callers to make code clear.

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   | 5 +++++
 mm/zsmalloc.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

mm/zpdesc.h +5 -0

index f64e813f4847..5db4fbe2d139 100644
@@ -114,6 +114,11 @@ static inline void __zpdesc_set_movable(struct zpdesc *zpdesc,
 	__SetPageMovable(zpdesc_page(zpdesc), mops);
 }
 
+static inline void __zpdesc_clear_movable(struct zpdesc *zpdesc)
+{
+	__ClearPageMovable(zpdesc_page(zpdesc));
+}
+
 static inline bool zpdesc_is_isolated(struct zpdesc *zpdesc)
 {
 	return PageIsolated(zpdesc_page(zpdesc));

mm/zsmalloc.c +1 -1

index bb8b5f13a966..e1d3ad50538c 100644
@@ -846,7 +846,7 @@ static void reset_zpdesc(struct zpdesc *zpdesc)
 {
 	struct page *page = zpdesc_page(zpdesc);
 
-	__ClearPageMovable(page);
+	__zpdesc_clear_movable(zpdesc);
 	ClearPagePrivate(page);
 	zpdesc->zspage = NULL;
 	zpdesc->next = NULL;

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #20 lore raw

PATCH v3 19/20 mm/zsmalloc: introduce __zpdesc_clear_zsmalloc

In reply to [email protected]

From: Alex Shi (Tencent) <[email protected]>

Add a helper __zpdesc_clear_zsmalloc() for __ClearPageZsmalloc(), and use it in callers to make code clear.

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   | 5 +++++
 mm/zsmalloc.c | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

mm/zpdesc.h +5 -0

index 5db4fbe2d139..05def4d45265 100644
@@ -119,6 +119,11 @@ static inline void __zpdesc_clear_movable(struct zpdesc *zpdesc)
 	__ClearPageMovable(zpdesc_page(zpdesc));
 }
 
+static inline void __zpdesc_clear_zsmalloc(struct zpdesc *zpdesc)
+{
+	__ClearPageZsmalloc(zpdesc_page(zpdesc));
+}
+
 static inline bool zpdesc_is_isolated(struct zpdesc *zpdesc)
 {
 	return PageIsolated(zpdesc_page(zpdesc));

mm/zsmalloc.c +2 -2

index e1d3ad50538c..d88602fb0233 100644
@@ -851,7 +851,7 @@ static void reset_zpdesc(struct zpdesc *zpdesc)
 	zpdesc->zspage = NULL;
 	zpdesc->next = NULL;
 	reset_first_obj_offset(zpdesc);
-	__ClearPageZsmalloc(page);
+	__zpdesc_clear_zsmalloc(zpdesc);
 }
 
 static int trylock_zspage(struct zspage *zspage)

@@ -1024,7 +1024,7 @@ static struct zspage *alloc_zspage(struct zs_pool *pool,
 		if (!zpdesc) {
 			while (--i >= 0) {
 				zpdesc_dec_zone_page_state(zpdescs[i]);
-				__ClearPageZsmalloc(zpdesc_page(zpdescs[i]));
+				__zpdesc_clear_zsmalloc(zpdescs[i]);
 				free_zpdesc(zpdescs[i]);
 			}
 			cache_free_zspage(pool, zspage);

Signature · 1 line

2.43.0

[email protected]

author

2024-07-08 06:29 UTC #21 lore raw

PATCH v3 20/20 mm/zsmalloc: introduce __zpdesc_set_zsmalloc()

In reply to [email protected]

From: Alex Shi (Tencent) <[email protected]>

Add a helper __zpdesc_set_zsmalloc() for __SetPageZsmalloc(), and use it in callers to make code clear.

Signed-off-by Alex Shi (Tencent) <[email protected]>

---
 mm/zpdesc.h   | 5 +++++
 mm/zsmalloc.c | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

mm/zpdesc.h +5 -0

index 05def4d45265..06371ce60cd1 100644
@@ -119,6 +119,11 @@ static inline void __zpdesc_clear_movable(struct zpdesc *zpdesc)
 	__ClearPageMovable(zpdesc_page(zpdesc));
 }
 
+static inline void __zpdesc_set_zsmalloc(struct zpdesc *zpdesc)
+{
+	__SetPageZsmalloc(zpdesc_page(zpdesc));
+}
+
 static inline void __zpdesc_clear_zsmalloc(struct zpdesc *zpdesc)
 {
 	__ClearPageZsmalloc(zpdesc_page(zpdesc));

mm/zsmalloc.c +2 -2

index d88602fb0233..7f8e02df4e3e 100644
@@ -1030,7 +1030,7 @@ static struct zspage *alloc_zspage(struct zs_pool *pool,
 			cache_free_zspage(pool, zspage);
 			return NULL;
 		}
-		__SetPageZsmalloc(zpdesc_page(zpdesc));
+		__zpdesc_set_zsmalloc(zpdesc);
 
 		zpdesc_inc_zone_page_state(zpdesc);
 		zpdescs[i] = zpdesc;

@@ -1820,7 +1820,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	VM_BUG_ON_PAGE(!zpdesc_is_isolated(zpdesc), zpdesc_page(zpdesc));
 
 	/* We're committed, tell the world that this is a Zsmalloc page. */
-	__SetPageZsmalloc(zpdesc_page(newzpdesc));
+	__zpdesc_set_zsmalloc(newzpdesc);
 
 	/* The page is locked, so this pointer must remain valid */
 	zspage = get_zspage(zpdesc);

Signature · 1 line

2.43.0

Alex Shi

2024-07-15 01:33 UTC #22 lore raw

In reply to [email protected]

Quoted 18 lines · On 7/8/24 2:33 PM, [email protected] wrote:

From: Alex Shi (Tencent) <[email protected]>
According to Metthew's plan, the page descriptor will be replace by a 8 bytes mem_desc on destination purpose.
https://lore.kernel.org/lkml/[email protected]/
Here is a implement on zsmalloc to replace page descriptor by 'zpdesc', which is still overlay on struct page now. but it's a step move forward above destination.
To name the struct zpdesc instead of zsdesc, since there are still 3 zpools under zswap: zbud, z3fold, zsmalloc for now(z3fold maybe removed soon), and we could easyly extend it to other zswap.zpool in needs.
For all zswap.zpools, they are all using single page since often used under memory pressure. So the conversion via folio series helper is better than page's for compound_head check saving.

Quoted 9 lines

For now, all zpools are using some page struct members, like page.flags for PG_private/PG_locked. and list_head lru, page.mapping for page migration.
This patachset does not increase the descriptor size nor introduce any functional changes, and could save about 122Kbytes zsmalloc.o size.
Thanks
Alex

Any comments for this patchset?

Thanks
Alex

Quoted 41 lines

---
v3->v2:
- Fix LKP reported build issue
- Update the Usage of struct zpdesc fields.
- Rebase onto latest mm-unstable commit 2073cda629a4
v1->v2:
- Take Yosry and Yoo's suggestion to add more members in zpdesc,
- Rebase on latest mm-unstable commit 31334cf98dbd
---
Alex Shi (Tencent) (9):
mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool mm/zsmalloc: use zpdesc in trylock_zspage/lock_zspage mm/zsmalloc: convert create_page_chain() and its users to use zpdesc mm/zsmalloc: rename reset_page to reset_zpdesc and use zpdesc in it mm/zsmalloc: convert SetZsPageMovable and remove unused funcs mm/zsmalloc: convert get/set_first_obj_offset() to take zpdesc mm/zsmalloc: introduce __zpdesc_clear_movable mm/zsmalloc: introduce __zpdesc_clear_zsmalloc mm/zsmalloc: introduce __zpdesc_set_zsmalloc()
Hyeonggon Yoo (11):
mm/zsmalloc: convert __zs_map_object/__zs_unmap_object to use zpdesc mm/zsmalloc: add and use pfn/zpdesc seeking funcs mm/zsmalloc: convert obj_malloc() to use zpdesc mm/zsmalloc: convert obj_allocated() and related helpers to use zpdesc mm/zsmalloc: convert init_zspage() to use zpdesc mm/zsmalloc: convert obj_to_page() and zs_free() to use zpdesc mm/zsmalloc: add zpdesc_is_isolated/zpdesc_zone helper for
zs_page_migrate
mm/zsmalloc: convert __free_zspage() to use zdsesc mm/zsmalloc: convert location_to_obj() to take zpdesc mm/zsmalloc: convert migrate_zspage() to use zpdesc mm/zsmalloc: convert get_zspage() to take zpdesc
 mm/zpdesc.h   | 146 ++++++++++++++++
 mm/zsmalloc.c | 460 +++++++++++++++++++++++++++-----------------------
 2 files changed, 398 insertions(+), 208 deletions(-)
 create mode 100644 mm/zpdesc.h

David Hildenbrand

2024-07-15 16:21 UTC #23 lore raw

Quoted 24 lines · Alex Shi

Quoted 21 lines · On 7/8/24 2:33 PM, [email protected] wrote:
From: Alex Shi (Tencent) <[email protected]>
According to Metthew's plan, the page descriptor will be replace by a 8 bytes mem_desc on destination purpose.
https://lore.kernel.org/lkml/[email protected]/
Here is a implement on zsmalloc to replace page descriptor by 'zpdesc', which is still overlay on struct page now. but it's a step move forward above destination.
To name the struct zpdesc instead of zsdesc, since there are still 3 zpools under zswap: zbud, z3fold, zsmalloc for now(z3fold maybe removed soon), and we could easyly extend it to other zswap.zpool in needs.
For all zswap.zpools, they are all using single page since often used under memory pressure. So the conversion via folio series helper is better than page's for compound_head check saving.
For now, all zpools are using some page struct members, like page.flags for PG_private/PG_locked. and list_head lru, page.mapping for page migration.

Quoted 8 lines

Quoted 6 lines
This patachset does not increase the descriptor size nor introduce any functional changes, and could save about 122Kbytes zsmalloc.o size.
Thanks
Alex
Any comments for this patchset?

Planning on taking a peek soon (busy traveling), but I'm hoping that people more familiar with the code can provide feedback.

Signature · 3 lines

Cheers,

David / dhildenb