[PATCH v4 8/9] mm/ksm: Convert chain series funcs and replace get_ksm_page
From: alexs
Date: Tue Apr 09 2024 - 05:27:19 EST
From: "Alex Shi (tencent)" <alexs@xxxxxxxxxx>
In ksm stable tree all page are single, let's convert them to use and
folios as well as stable_tree_insert/stable_tree_search funcs.
And replace get_ksm_page() by ksm_get_folio() since there is no more
needs.
It could save a few compound_head calls.
Signed-off-by: Alex Shi (tencent) <alexs@xxxxxxxxxx>
Cc: Izik Eidus <izik.eidus@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Chris Wright <chrisw@xxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/ksm.c | 150 +++++++++++++++++++++++++--------------------------
mm/migrate.c | 2 +-
2 files changed, 73 insertions(+), 79 deletions(-)
diff --git a/mm/ksm.c b/mm/ksm.c
index 776094fab34e..a705ed16aa1b 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -890,14 +890,14 @@ static void remove_node_from_stable_tree(struct ksm_stable_node *stable_node)
free_stable_node(stable_node);
}
-enum get_ksm_page_flags {
+enum ksm_get_folio_flags {
GET_KSM_PAGE_NOLOCK,
GET_KSM_PAGE_LOCK,
GET_KSM_PAGE_TRYLOCK
};
/*
- * get_ksm_page: checks if the page indicated by the stable node
+ * ksm_get_folio: checks if the page indicated by the stable node
* is still its ksm page, despite having held no reference to it.
* In which case we can trust the content of the page, and it
* returns the gotten page; but if the page has now been zapped,
@@ -916,7 +916,7 @@ enum get_ksm_page_flags {
* is on its way to being freed; but it is an anomaly to bear in mind.
*/
static struct folio *ksm_get_folio(struct ksm_stable_node *stable_node,
- enum get_ksm_page_flags flags)
+ enum ksm_get_folio_flags flags)
{
struct folio *folio;
void *expected_mapping;
@@ -990,14 +990,6 @@ static struct folio *ksm_get_folio(struct ksm_stable_node *stable_node,
return NULL;
}
-static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
- enum get_ksm_page_flags flags)
-{
- struct folio *folio = ksm_get_folio(stable_node, flags);
-
- return &folio->page;
-}
-
/*
* Removing rmap_item from stable or unstable tree.
* This function will clean the information from the stable/unstable tree.
@@ -1127,7 +1119,7 @@ static int remove_stable_node(struct ksm_stable_node *stable_node)
folio = ksm_get_folio(stable_node, GET_KSM_PAGE_LOCK);
if (!folio) {
/*
- * get_ksm_page did remove_node_from_stable_tree itself.
+ * ksm_get_folio did remove_node_from_stable_tree itself.
*/
return 0;
}
@@ -1140,7 +1132,7 @@ static int remove_stable_node(struct ksm_stable_node *stable_node)
err = -EBUSY;
if (!folio_mapped(folio)) {
/*
- * The stable node did not yet appear stale to get_ksm_page(),
+ * The stable node did not yet appear stale to ksm_get_folio(),
* since that allows for an unmapped ksm folio to be recognized
* right up until it is freed; but the node is safe to remove.
* This folio might be in an LRU cache waiting to be freed,
@@ -1632,10 +1624,10 @@ bool is_page_sharing_candidate(struct ksm_stable_node *stable_node)
return __is_page_sharing_candidate(stable_node, 0);
}
-static struct page *stable_node_dup(struct ksm_stable_node **_stable_node_dup,
- struct ksm_stable_node **_stable_node,
- struct rb_root *root,
- bool prune_stale_stable_nodes)
+static struct folio *stable_node_dup(struct ksm_stable_node **_stable_node_dup,
+ struct ksm_stable_node **_stable_node,
+ struct rb_root *root,
+ bool prune_stale_stable_nodes)
{
struct ksm_stable_node *dup, *found = NULL, *stable_node = *_stable_node;
struct hlist_node *hlist_safe;
@@ -1658,7 +1650,7 @@ static struct page *stable_node_dup(struct ksm_stable_node **_stable_node_dup,
* We must walk all stable_node_dup to prune the stale
* stable nodes during lookup.
*
- * get_ksm_page can drop the nodes from the
+ * ksm_get_folio can drop the nodes from the
* stable_node->hlist if they point to freed pages
* (that's why we do a _safe walk). The "dup"
* stable_node parameter itself will be freed from
@@ -1748,7 +1740,7 @@ static struct page *stable_node_dup(struct ksm_stable_node **_stable_node_dup,
}
*_stable_node_dup = found;
- return &tree_folio->page;
+ return tree_folio;
}
static struct ksm_stable_node *stable_node_dup_any(struct ksm_stable_node *stable_node,
@@ -1765,7 +1757,7 @@ static struct ksm_stable_node *stable_node_dup_any(struct ksm_stable_node *stabl
}
/*
- * Like for get_ksm_page, this function can free the *_stable_node and
+ * Like for ksm_get_folio, this function can free the *_stable_node and
* *_stable_node_dup if the returned tree_page is NULL.
*
* It can also free and overwrite *_stable_node with the found
@@ -1778,16 +1770,16 @@ static struct ksm_stable_node *stable_node_dup_any(struct ksm_stable_node *stabl
* function and will be overwritten in all cases, the caller doesn't
* need to initialize it.
*/
-static struct page *__stable_node_chain(struct ksm_stable_node **_stable_node_dup,
- struct ksm_stable_node **_stable_node,
- struct rb_root *root,
- bool prune_stale_stable_nodes)
+static struct folio *__stable_node_chain(struct ksm_stable_node **_stable_node_dup,
+ struct ksm_stable_node **_stable_node,
+ struct rb_root *root,
+ bool prune_stale_stable_nodes)
{
struct ksm_stable_node *stable_node = *_stable_node;
if (!is_stable_node_chain(stable_node)) {
if (is_page_sharing_candidate(stable_node)) {
*_stable_node_dup = stable_node;
- return get_ksm_page(stable_node, GET_KSM_PAGE_NOLOCK);
+ return ksm_get_folio(stable_node, GET_KSM_PAGE_NOLOCK);
}
/*
* _stable_node_dup set to NULL means the stable_node
@@ -1800,24 +1792,24 @@ static struct page *__stable_node_chain(struct ksm_stable_node **_stable_node_du
prune_stale_stable_nodes);
}
-static __always_inline struct page *chain_prune(struct ksm_stable_node **s_n_d,
- struct ksm_stable_node **s_n,
- struct rb_root *root)
+static __always_inline struct folio *chain_prune(struct ksm_stable_node **s_n_d,
+ struct ksm_stable_node **s_n,
+ struct rb_root *root)
{
return __stable_node_chain(s_n_d, s_n, root, true);
}
-static __always_inline struct page *chain(struct ksm_stable_node **s_n_d,
- struct ksm_stable_node *s_n,
- struct rb_root *root)
+static __always_inline struct folio *chain(struct ksm_stable_node **s_n_d,
+ struct ksm_stable_node *s_n,
+ struct rb_root *root)
{
struct ksm_stable_node *old_stable_node = s_n;
- struct page *tree_page;
+ struct folio *tree_folio;
- tree_page = __stable_node_chain(s_n_d, &s_n, root, false);
+ tree_folio = __stable_node_chain(s_n_d, &s_n, root, false);
/* not pruning dups so s_n cannot have changed */
VM_BUG_ON(s_n != old_stable_node);
- return tree_page;
+ return tree_folio;
}
/*
@@ -1829,7 +1821,7 @@ static __always_inline struct page *chain(struct ksm_stable_node **s_n_d,
* This function returns the stable tree node of identical content if found,
* NULL otherwise.
*/
-static struct page *stable_tree_search(struct page *page)
+static void *stable_tree_search(struct page *page)
{
int nid;
struct rb_root *root;
@@ -1837,28 +1829,30 @@ static struct page *stable_tree_search(struct page *page)
struct rb_node *parent;
struct ksm_stable_node *stable_node, *stable_node_dup, *stable_node_any;
struct ksm_stable_node *page_node;
+ struct folio *folio;
- page_node = page_stable_node(page);
+ folio = page_folio(page);
+ page_node = folio_stable_node(folio);
if (page_node && page_node->head != &migrate_nodes) {
/* ksm page forked */
- get_page(page);
- return page;
+ folio_get(folio);
+ return folio;
}
- nid = get_kpfn_nid(page_to_pfn(page));
+ nid = get_kpfn_nid(folio_pfn(folio));
root = root_stable_tree + nid;
again:
new = &root->rb_node;
parent = NULL;
while (*new) {
- struct page *tree_page;
+ struct folio *tree_folio;
int ret;
cond_resched();
stable_node = rb_entry(*new, struct ksm_stable_node, node);
stable_node_any = NULL;
- tree_page = chain_prune(&stable_node_dup, &stable_node, root);
+ tree_folio = chain_prune(&stable_node_dup, &stable_node, root);
/*
* NOTE: stable_node may have been freed by
* chain_prune() if the returned stable_node_dup is
@@ -1892,14 +1886,14 @@ static struct page *stable_tree_search(struct page *page)
* write protected at all times. Any will work
* fine to continue the walk.
*/
- tree_page = get_ksm_page(stable_node_any,
- GET_KSM_PAGE_NOLOCK);
+ tree_folio = ksm_get_folio(stable_node_any,
+ GET_KSM_PAGE_NOLOCK);
}
VM_BUG_ON(!stable_node_dup ^ !!stable_node_any);
- if (!tree_page) {
+ if (!tree_folio) {
/*
* If we walked over a stale stable_node,
- * get_ksm_page() will call rb_erase() and it
+ * ksm_get_folio() will call rb_erase() and it
* may rebalance the tree from under us. So
* restart the search from scratch. Returning
* NULL would be safe too, but we'd generate
@@ -1909,8 +1903,8 @@ static struct page *stable_tree_search(struct page *page)
goto again;
}
- ret = memcmp_pages(page, tree_page);
- put_page(tree_page);
+ ret = memcmp_pages(page, &tree_folio->page);
+ folio_put(tree_folio);
parent = *new;
if (ret < 0)
@@ -1953,26 +1947,26 @@ static struct page *stable_tree_search(struct page *page)
* It would be more elegant to return stable_node
* than kpage, but that involves more changes.
*/
- tree_page = get_ksm_page(stable_node_dup,
- GET_KSM_PAGE_TRYLOCK);
+ tree_folio = ksm_get_folio(stable_node_dup,
+ GET_KSM_PAGE_TRYLOCK);
- if (PTR_ERR(tree_page) == -EBUSY)
+ if (PTR_ERR(tree_folio) == -EBUSY)
return ERR_PTR(-EBUSY);
- if (unlikely(!tree_page))
+ if (unlikely(!tree_folio))
/*
* The tree may have been rebalanced,
* so re-evaluate parent and new.
*/
goto again;
- unlock_page(tree_page);
+ folio_unlock(tree_folio);
if (get_kpfn_nid(stable_node_dup->kpfn) !=
NUMA(stable_node_dup->nid)) {
- put_page(tree_page);
+ folio_put(tree_folio);
goto replace;
}
- return tree_page;
+ return tree_folio;
}
}
@@ -1985,8 +1979,8 @@ static struct page *stable_tree_search(struct page *page)
rb_insert_color(&page_node->node, root);
out:
if (is_page_sharing_candidate(page_node)) {
- get_page(page);
- return page;
+ folio_get(folio);
+ return folio;
} else
return NULL;
@@ -2011,12 +2005,12 @@ static struct page *stable_tree_search(struct page *page)
&page_node->node,
root);
if (is_page_sharing_candidate(page_node))
- get_page(page);
+ folio_get(folio);
else
- page = NULL;
+ folio = NULL;
} else {
rb_erase(&stable_node_dup->node, root);
- page = NULL;
+ folio = NULL;
}
} else {
VM_BUG_ON(!is_stable_node_chain(stable_node));
@@ -2027,16 +2021,16 @@ static struct page *stable_tree_search(struct page *page)
DO_NUMA(page_node->nid = nid);
stable_node_chain_add_dup(page_node, stable_node);
if (is_page_sharing_candidate(page_node))
- get_page(page);
+ folio_get(folio);
else
- page = NULL;
+ folio = NULL;
} else {
- page = NULL;
+ folio = NULL;
}
}
stable_node_dup->head = &migrate_nodes;
list_add(&stable_node_dup->list, stable_node_dup->head);
- return page;
+ return folio;
chain_append:
/* stable_node_dup could be null if it reached the limit */
@@ -2079,7 +2073,7 @@ static struct page *stable_tree_search(struct page *page)
* This function returns the stable tree node just allocated on success,
* NULL otherwise.
*/
-static struct ksm_stable_node *stable_tree_insert(struct page *kpage)
+static struct ksm_stable_node *stable_tree_insert(struct folio *kfolio)
{
int nid;
unsigned long kpfn;
@@ -2089,7 +2083,7 @@ static struct ksm_stable_node *stable_tree_insert(struct page *kpage)
struct ksm_stable_node *stable_node, *stable_node_dup, *stable_node_any;
bool need_chain = false;
- kpfn = page_to_pfn(kpage);
+ kpfn = folio_pfn(kfolio);
nid = get_kpfn_nid(kpfn);
root = root_stable_tree + nid;
again:
@@ -2097,13 +2091,13 @@ static struct ksm_stable_node *stable_tree_insert(struct page *kpage)
new = &root->rb_node;
while (*new) {
- struct page *tree_page;
+ struct folio *tree_folio;
int ret;
cond_resched();
stable_node = rb_entry(*new, struct ksm_stable_node, node);
stable_node_any = NULL;
- tree_page = chain(&stable_node_dup, stable_node, root);
+ tree_folio = chain(&stable_node_dup, stable_node, root);
if (!stable_node_dup) {
/*
* Either all stable_node dups were full in
@@ -2125,14 +2119,14 @@ static struct ksm_stable_node *stable_tree_insert(struct page *kpage)
* write protected at all times. Any will work
* fine to continue the walk.
*/
- tree_page = get_ksm_page(stable_node_any,
- GET_KSM_PAGE_NOLOCK);
+ tree_folio = ksm_get_folio(stable_node_any,
+ GET_KSM_PAGE_NOLOCK);
}
VM_BUG_ON(!stable_node_dup ^ !!stable_node_any);
- if (!tree_page) {
+ if (!tree_folio) {
/*
* If we walked over a stale stable_node,
- * get_ksm_page() will call rb_erase() and it
+ * ksm_get_folio() will call rb_erase() and it
* may rebalance the tree from under us. So
* restart the search from scratch. Returning
* NULL would be safe too, but we'd generate
@@ -2142,8 +2136,8 @@ static struct ksm_stable_node *stable_tree_insert(struct page *kpage)
goto again;
}
- ret = memcmp_pages(kpage, tree_page);
- put_page(tree_page);
+ ret = memcmp_pages(&kfolio->page, &tree_folio->page);
+ folio_put(tree_folio);
parent = *new;
if (ret < 0)
@@ -2162,7 +2156,7 @@ static struct ksm_stable_node *stable_tree_insert(struct page *kpage)
INIT_HLIST_HEAD(&stable_node_dup->hlist);
stable_node_dup->kpfn = kpfn;
- set_page_stable_node(kpage, stable_node_dup);
+ folio_set_stable_node(kfolio, stable_node_dup);
stable_node_dup->rmap_hlist_len = 0;
DO_NUMA(stable_node_dup->nid = nid);
if (!need_chain) {
@@ -2440,7 +2434,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
* node in the stable tree and add both rmap_items.
*/
lock_page(kpage);
- stable_node = stable_tree_insert(kpage);
+ stable_node = stable_tree_insert(page_folio(kpage));
if (stable_node) {
stable_tree_append(tree_rmap_item, stable_node,
false);
@@ -3244,7 +3238,7 @@ void folio_migrate_ksm(struct folio *newfolio, struct folio *folio)
/*
* newfolio->mapping was set in advance; now we need smp_wmb()
* to make sure that the new stable_node->kpfn is visible
- * to get_ksm_page() before it can see that folio->mapping
+ * to ksm_get_folio() before it can see that folio->mapping
* has gone stale (or that folio_test_swapcache has been cleared).
*/
smp_wmb();
@@ -3271,7 +3265,7 @@ static bool stable_node_dup_remove_range(struct ksm_stable_node *stable_node,
if (stable_node->kpfn >= start_pfn &&
stable_node->kpfn < end_pfn) {
/*
- * Don't get_ksm_page, page has already gone:
+ * Don't ksm_get_folio, page has already gone:
* which is why we keep kpfn instead of page*
*/
remove_node_from_stable_tree(stable_node);
@@ -3359,7 +3353,7 @@ static int ksm_memory_callback(struct notifier_block *self,
* Most of the work is done by page migration; but there might
* be a few stable_nodes left over, still pointing to struct
* pages which have been offlined: prune those from the tree,
- * otherwise get_ksm_page() might later try to access a
+ * otherwise ksm_get_folio() might later try to access a
* non-existent struct page.
*/
ksm_check_stable_tree(mn->start_pfn,
diff --git a/mm/migrate.c b/mm/migrate.c
index 73a052a382f1..9f0494fd902c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -616,7 +616,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
folio_migrate_ksm(newfolio, folio);
/*
* Please do not reorder this without considering how mm/ksm.c's
- * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
+ * ksm_get_folio() depends upon ksm_migrate_page() and PageSwapCache().
*/
if (folio_test_swapcache(folio))
folio_clear_swapcache(folio);
--
2.43.0