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Message-ID: <20240813084611.4122571-22-alexs@kernel.org>
Date: Tue, 13 Aug 2024 16:46:07 +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 v6 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 | 47 ++++++++++++++++++++++++++---------------------
1 file changed, 26 insertions(+), 21 deletions(-)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 3dbe6bfa656b..37619f4b074b 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -17,14 +17,16 @@
*
* Usage of struct zpdesc fields:
* zpdesc->zspage: points to zspage
- * zpdesc->next: links together all component pages of a 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.
* 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
+ * PG_private: identifies the first component zpdesc
+ * PG_lock: lock all component zpdescs for a zspage free, serialize with
+ * migration
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -191,7 +193,10 @@ 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;
@@ -907,7 +912,7 @@ 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)) {
@@ -964,7 +969,7 @@ 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;
@@ -973,9 +978,9 @@ 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).
@@ -1033,7 +1038,7 @@ 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;
@@ -1360,7 +1365,7 @@ 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);
@@ -1693,19 +1698,19 @@ 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);
@@ -1780,7 +1785,7 @@ 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)))
@@ -1791,8 +1796,8 @@ 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);
@@ -1819,7 +1824,7 @@ 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;
@@ -1892,7 +1897,7 @@ 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)
--
2.43.0
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