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Message-ID: <20240628031138.429622-2-alexs@kernel.org>
Date: Fri, 28 Jun 2024 11:11:16 +0800
From: alexs@...nel.org
To: Vitaly Wool <vitaly.wool@...sulko.com>,
Miaohe Lin <linmiaohe@...wei.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
minchan@...nel.org,
willy@...radead.org,
senozhatsky@...omium.org,
david@...hat.com,
42.hyeyoo@...il.com
Cc: Alex Shi <alexs@...nel.org>
Subject: [PATCH 01/20] mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool
From: Alex Shi <alexs@...nel.org>
The 1st patch introduces new memory decriptor zpdesc and rename
zspage.first_page to zspage.first_zpdesc, no functional change.
Originally-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
Signed-off-by: Alex Shi <alexs@...nel.org>
---
mm/zpdesc.h | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++
mm/zsmalloc.c | 19 ++++++++---------
2 files changed, 66 insertions(+), 9 deletions(-)
create mode 100644 mm/zpdesc.h
diff --git a/mm/zpdesc.h b/mm/zpdesc.h
new file mode 100644
index 000000000000..a1ab5ebaa936
--- /dev/null
+++ b/mm/zpdesc.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* zpdesc.h: zswap.zpool memory descriptor
+ *
+ * Written by Alex Shi <alexs@...nel.org>
+ * Hyeonggon Yoo <42.hyeyoo@...il.com>
+ */
+#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: Indirected 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
+ *
+ * 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;
+ unsigned long _zp_pad_1;
+ union {
+ /* Next zpdescs in a zspage in zsmalloc zpool */
+ struct zpdesc *next;
+ /* For huge zspage in zsmalloc zpool */
+ unsigned long handle;
+ };
+ struct zspage *zspage;
+};
+#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(index, next);
+ZPDESC_MATCH(index, handle);
+ZPDESC_MATCH(private, zspage);
+#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
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index fec1a39e5bbe..67bb80b7413a 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -13,17 +13,17 @@
/*
* 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
*
@@ -64,6 +64,7 @@
#include <linux/pagemap.h>
#include <linux/fs.h>
#include <linux/local_lock.h>
+#include "zpdesc.h"
#define ZSPAGE_MAGIC 0x58
@@ -253,7 +254,7 @@ 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 +449,7 @@ 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 +949,7 @@ 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))
@@ -1325,7 +1326,7 @@ static unsigned long obj_malloc(struct zs_pool *pool,
link->handle = handle;
else
/* record handle to page->index */
- zspage->first_page->index = handle;
+ zspage->first_zpdesc->handle = handle;
kunmap_atomic(vaddr);
mod_zspage_inuse(zspage, 1);
--
2.43.0
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