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Message-ID: <20240902072136.578720-22-alexs@kernel.org>
Date: Mon, 2 Sep 2024 15:21:32 +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,
Yosry Ahmed <yosryahmed@...gle.com>,
nphamcs@...il.com
Cc: Alex Shi <alexs@...nel.org>
Subject: [PATCH v7 21/21] mm/zsmalloc: update comments for page->zpdesc changes
From: Alex Shi <alexs@...nel.org>
After the page to zpdesc conversion, there still left few comments or
function named with page not zpdesc, let's update the comments and
rename function create_page_chain() as create_zpdesc_chain().
Signed-off-by: Alex Shi <alexs@...nel.org>
---
mm/zsmalloc.c | 61 ++++++++++++++++++++++++++-------------------------
1 file changed, 31 insertions(+), 30 deletions(-)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 849f192d4937..1e47cda05c83 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -13,20 +13,19 @@
/*
* 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 zpdescs of a zspage
* For the huge page, this is always 0, so we use this field
* to store handle.
- * page->page_type: PGTY_zsmalloc, lower 24 bits locate the first object
- * offset in a subpage of a zspage
- *
- * Usage of struct page flags:
- * PG_private: identifies the first component page
- * PG_owner_priv_1: identifies the huge component page
+ * zpdesc->first_obj_offset: PGTY_zsmalloc, lower 24 bits locate the first
+ * object offset in a subpage of a zspage
*
+ * Usage of struct zpdesc(page) flags:
+ * PG_private: identifies the first component zpdesc
+ * PG_lock: lock all component zpdescs for a zspage free, serialize with
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -191,7 +190,10 @@ struct size_class {
*/
int size;
int objs_per_zspage;
- /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
+ /*
+ * Number of PAGE_SIZE sized zpdescs/pages to combine to
+ * form a 'zspage'
+ */
int pages_per_zspage;
unsigned int index;
@@ -900,7 +902,7 @@ static void free_zspage(struct zs_pool *pool, struct size_class *class,
/*
* Since zs_free couldn't be sleepable, this function cannot call
- * lock_page. The page locks trylock_zspage got will be released
+ * lock_page. The zpdesc locks trylock_zspage got will be released
* by __free_zspage.
*/
if (!trylock_zspage(zspage)) {
@@ -957,7 +959,7 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
set_freeobj(zspage, 0);
}
-static void create_page_chain(struct size_class *class, struct zspage *zspage,
+static void create_zpdesc_chain(struct size_class *class, struct zspage *zspage,
struct zpdesc *zpdescs[])
{
int i;
@@ -966,9 +968,9 @@ static void create_page_chain(struct size_class *class, struct zspage *zspage,
int nr_zpdescs = class->pages_per_zspage;
/*
- * Allocate individual pages and link them together as:
- * 1. all pages are linked together using zpdesc->next
- * 2. each sub-page point to zspage using zpdesc->zspage
+ * Allocate individual zpdescs and link them together as:
+ * 1. all zpdescs are linked together using zpdesc->next
+ * 2. each sub-zpdesc point to zspage using zpdesc->zspage
*
* we set PG_private to identify the first zpdesc (i.e. no other zpdesc
* has this flag set).
@@ -1026,7 +1028,7 @@ static struct zspage *alloc_zspage(struct zs_pool *pool,
zpdescs[i] = zpdesc;
}
- create_page_chain(class, zspage, zpdescs);
+ create_zpdesc_chain(class, zspage, zpdescs);
init_zspage(class, zspage);
zspage->pool = pool;
zspage->class = class->index;
@@ -1353,7 +1355,7 @@ static unsigned long obj_malloc(struct zs_pool *pool,
/* record handle in the header of allocated chunk */
link->handle = handle | OBJ_ALLOCATED_TAG;
else
- /* record handle to page->index */
+ /* record handle to zpdesc->handle */
zspage->first_zpdesc->handle = handle | OBJ_ALLOCATED_TAG;
kunmap_atomic(vaddr);
@@ -1443,7 +1445,6 @@ static void obj_free(int class_size, unsigned long obj)
unsigned int f_objidx;
void *vaddr;
-
obj_to_location(obj, &f_zpdesc, &f_objidx);
f_offset = offset_in_page(class_size * f_objidx);
zspage = get_zspage(f_zpdesc);
@@ -1686,19 +1687,19 @@ static int putback_zspage(struct size_class *class, struct zspage *zspage)
#ifdef CONFIG_COMPACTION
/*
* To prevent zspage destroy during migration, zspage freeing should
- * hold locks of all pages in the zspage.
+ * hold locks of all component zpdesc in the zspage.
*/
static void lock_zspage(struct zspage *zspage)
{
struct zpdesc *curr_zpdesc, *zpdesc;
/*
- * Pages we haven't locked yet can be migrated off the list while we're
+ * Zpdesc we haven't locked yet can be migrated off the list while we're
* trying to lock them, so we need to be careful and only attempt to
- * lock each page under migrate_read_lock(). Otherwise, the page we lock
- * may no longer belong to the zspage. This means that we may wait for
- * the wrong page to unlock, so we must take a reference to the page
- * prior to waiting for it to unlock outside migrate_read_lock().
+ * lock each zpdesc under migrate_read_lock(). Otherwise, the zpdesc we
+ * lock may no longer belong to the zspage. This means that we may wait
+ * for the wrong zpdesc to unlock, so we must take a reference to the
+ * zpdesc prior to waiting for it to unlock outside migrate_read_lock().
*/
while (1) {
migrate_read_lock(zspage);
@@ -1773,7 +1774,7 @@ static void replace_sub_page(struct size_class *class, struct zspage *zspage,
idx++;
} while ((zpdesc = get_next_zpdesc(zpdesc)) != NULL);
- create_page_chain(class, zspage, zpdescs);
+ create_zpdesc_chain(class, zspage, zpdescs);
first_obj_offset = get_first_obj_offset(oldzpdesc);
set_first_obj_offset(newzpdesc, first_obj_offset);
if (unlikely(ZsHugePage(zspage)))
@@ -1784,8 +1785,8 @@ static void replace_sub_page(struct size_class *class, struct zspage *zspage,
static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
{
/*
- * Page is locked so zspage couldn't be destroyed. For detail, look at
- * lock_zspage in free_zspage.
+ * Page/zpdesc is locked so zspage couldn't be destroyed. For detail,
+ * look at lock_zspage in free_zspage.
*/
VM_BUG_ON_PAGE(PageIsolated(page), page);
@@ -1812,7 +1813,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
/* We're committed, tell the world that this is a Zsmalloc page. */
__zpdesc_set_zsmalloc(newzpdesc);
- /* The page is locked, so this pointer must remain valid */
+ /* The zpdesc/page is locked, so this pointer must remain valid */
zspage = get_zspage(zpdesc);
pool = zspage->pool;
@@ -1885,7 +1886,7 @@ static const struct movable_operations zsmalloc_mops = {
};
/*
- * Caller should hold page_lock of all pages in the zspage
+ * Caller should hold zpdesc locks of all in the zspage
* In here, we cannot use zspage meta data.
*/
static void async_free_zspage(struct work_struct *work)
--
2.46.0
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