The patch titled
Subject: mm/zsmalloc: use zpdesc in trylock_zspage()/lock_zspage()
has been added to the -mm mm-unstable branch. Its filename is
mm-zsmalloc-use-zpdesc-in-trylock_zspage-lock_zspage.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zsmalloc-use-zpdesc-in-trylock_zspage-lock_zspage.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Alex Shi <alexs@xxxxxxxxxx>
Subject: mm/zsmalloc: use zpdesc in trylock_zspage()/lock_zspage()
Date: Tue, 17 Dec 2024 00:04:33 +0900
Convert trylock_zspage() and lock_zspage() to use zpdesc. To achieve
that, introduce a couple of helper functions:
- zpdesc_lock()
- zpdesc_unlock()
- zpdesc_trylock()
- zpdesc_wait_locked()
- zpdesc_get()
- zpdesc_put()
Here we use the folio version of functions for 2 reasons. First,
zswap.zpool currently only uses order-0 pages and using folio could save
some compound_head checks. Second, folio_put could bypass devmap checking
that we don't need.
BTW, thanks Intel LKP found a build warning on the patch.
Originally-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20241216150450.1228021-3-42.hyeyoo@xxxxxxxxx
Signed-off-by: Alex Shi <alexs@xxxxxxxxxx>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Acked-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Tested-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zpdesc.h | 30 ++++++++++++++++++++++
mm/zsmalloc.c | 64 ++++++++++++++++++++++++++++++++----------------
2 files changed, 73 insertions(+), 21 deletions(-)
--- a/mm/zpdesc.h~mm-zsmalloc-use-zpdesc-in-trylock_zspage-lock_zspage
+++ a/mm/zpdesc.h
@@ -104,4 +104,34 @@ static_assert(sizeof(struct zpdesc) <= s
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
--- a/mm/zsmalloc.c~mm-zsmalloc-use-zpdesc-in-trylock_zspage-lock_zspage
+++ a/mm/zsmalloc.c
@@ -428,13 +428,17 @@ static __maybe_unused int is_first_page(
return PagePrivate(page);
}
+static inline bool is_first_zpdesc(struct zpdesc *zpdesc)
+{
+ return PagePrivate(zpdesc_page(zpdesc));
+}
+
/* Protected by class->lock */
static inline int get_zspage_inuse(struct zspage *zspage)
{
return zspage->inuse;
}
-
static inline void mod_zspage_inuse(struct zspage *zspage, int val)
{
zspage->inuse += val;
@@ -448,6 +452,14 @@ static inline struct page *get_first_pag
return first_page;
}
+static struct zpdesc *get_first_zpdesc(struct zspage *zspage)
+{
+ struct zpdesc *first_zpdesc = zspage->first_zpdesc;
+
+ VM_BUG_ON_PAGE(!is_first_zpdesc(first_zpdesc), zpdesc_page(first_zpdesc));
+ return first_zpdesc;
+}
+
#define FIRST_OBJ_PAGE_TYPE_MASK 0xffffff
static inline unsigned int get_first_obj_offset(struct page *page)
@@ -734,6 +746,16 @@ static struct page *get_next_page(struct
return (struct page *)page->index;
}
+static struct zpdesc *get_next_zpdesc(struct zpdesc *zpdesc)
+{
+ struct zspage *zspage = get_zspage(zpdesc_page(zpdesc));
+
+ if (unlikely(ZsHugePage(zspage)))
+ return NULL;
+
+ return zpdesc->next;
+}
+
/**
* obj_to_location - get (<page>, <obj_idx>) from encoded object value
* @obj: the encoded object value
@@ -803,11 +825,11 @@ static void reset_page(struct page *page
static int trylock_zspage(struct zspage *zspage)
{
- struct page *cursor, *fail;
+ struct zpdesc *cursor, *fail;
- for (cursor = get_first_page(zspage); cursor != NULL; cursor =
- get_next_page(cursor)) {
- if (!trylock_page(cursor)) {
+ for (cursor = get_first_zpdesc(zspage); cursor != NULL; cursor =
+ get_next_zpdesc(cursor)) {
+ if (!zpdesc_trylock(cursor)) {
fail = cursor;
goto unlock;
}
@@ -815,9 +837,9 @@ static int trylock_zspage(struct zspage
return 1;
unlock:
- for (cursor = get_first_page(zspage); cursor != fail; cursor =
- get_next_page(cursor))
- unlock_page(cursor);
+ for (cursor = get_first_zpdesc(zspage); cursor != fail; cursor =
+ get_next_zpdesc(cursor))
+ zpdesc_unlock(cursor);
return 0;
}
@@ -1635,7 +1657,7 @@ static int putback_zspage(struct size_cl
*/
static void lock_zspage(struct zspage *zspage)
{
- struct page *curr_page, *page;
+ struct zpdesc *curr_zpdesc, *zpdesc;
/*
* Pages we haven't locked yet can be migrated off the list while we're
@@ -1647,24 +1669,24 @@ static void lock_zspage(struct zspage *z
*/
while (1) {
migrate_read_lock(zspage);
- page = get_first_page(zspage);
- if (trylock_page(page))
+ zpdesc = get_first_zpdesc(zspage);
+ if (zpdesc_trylock(zpdesc))
break;
- get_page(page);
+ zpdesc_get(zpdesc);
migrate_read_unlock(zspage);
- wait_on_page_locked(page);
- put_page(page);
+ zpdesc_wait_locked(zpdesc);
+ zpdesc_put(zpdesc);
}
- curr_page = page;
- while ((page = get_next_page(curr_page))) {
- if (trylock_page(page)) {
- curr_page = page;
+ curr_zpdesc = zpdesc;
+ while ((zpdesc = get_next_zpdesc(curr_zpdesc))) {
+ if (zpdesc_trylock(zpdesc)) {
+ curr_zpdesc = zpdesc;
} else {
- get_page(page);
+ zpdesc_get(zpdesc);
migrate_read_unlock(zspage);
- wait_on_page_locked(page);
- put_page(page);
+ zpdesc_wait_locked(zpdesc);
+ zpdesc_put(zpdesc);
migrate_read_lock(zspage);
}
}
_
Patches currently in -mm which might be from alexs@xxxxxxxxxx are
mm-zsmalloc-add-zpdesc-memory-descriptor-for-zswapzpool.patch
mm-zsmalloc-use-zpdesc-in-trylock_zspage-lock_zspage.patch
mm-zsmalloc-convert-create_page_chain-and-its-users-to-use-zpdesc.patch
mm-zsmalloc-convert-reset_page-to-reset_zpdesc.patch
mm-zsmalloc-convert-setzspagemovable-and-remove-unused-funcs.patch
mm-zsmalloc-convert-get-set_first_obj_offset-to-take-zpdesc.patch
mm-zsmalloc-introduce-__zpdesc_clear-set_zsmalloc.patch
