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authorMatthew Wilcox (Oracle) <willy@infradead.org>2022-06-07 22:38:48 +0300
committerMatthew Wilcox (Oracle) <willy@infradead.org>2022-08-02 19:34:03 +0300
commit68f2736a858324c3ec852f6c2cddd9d1c777357d (patch)
tree62c9573d493277ee9eb7edb13276570e395d8e8f /include/linux/migrate.h
parent81218f80a70768589ee30e14a8889336f070a339 (diff)
downloadlinux-68f2736a858324c3ec852f6c2cddd9d1c777357d.tar.xz
mm: Convert all PageMovable users to movable_operations
These drivers are rather uncomfortably hammered into the address_space_operations hole. They aren't filesystems and don't behave like filesystems. They just need their own movable_operations structure, which we can point to directly from page->mapping. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Diffstat (limited to 'include/linux/migrate.h')
-rw-r--r--include/linux/migrate.h56
1 files changed, 51 insertions, 5 deletions
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 069a89e847f3..82c735ba6109 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -19,6 +19,43 @@ struct migration_target_control;
*/
#define MIGRATEPAGE_SUCCESS 0
+/**
+ * struct movable_operations - Driver page migration
+ * @isolate_page:
+ * The VM calls this function to prepare the page to be moved. The page
+ * is locked and the driver should not unlock it. The driver should
+ * return ``true`` if the page is movable and ``false`` if it is not
+ * currently movable. After this function returns, the VM uses the
+ * page->lru field, so the driver must preserve any information which
+ * is usually stored here.
+ *
+ * @migrate_page:
+ * After isolation, the VM calls this function with the isolated
+ * @src page. The driver should copy the contents of the
+ * @src page to the @dst page and set up the fields of @dst page.
+ * Both pages are locked.
+ * If page migration is successful, the driver should call
+ * __ClearPageMovable(@src) and return MIGRATEPAGE_SUCCESS.
+ * If the driver cannot migrate the page at the moment, it can return
+ * -EAGAIN. The VM interprets this as a temporary migration failure and
+ * will retry it later. Any other error value is a permanent migration
+ * failure and migration will not be retried.
+ * The driver shouldn't touch the @src->lru field while in the
+ * migrate_page() function. It may write to @dst->lru.
+ *
+ * @putback_page:
+ * If migration fails on the isolated page, the VM informs the driver
+ * that the page is no longer a candidate for migration by calling
+ * this function. The driver should put the isolated page back into
+ * its own data structure.
+ */
+struct movable_operations {
+ bool (*isolate_page)(struct page *, isolate_mode_t);
+ int (*migrate_page)(struct page *dst, struct page *src,
+ enum migrate_mode);
+ void (*putback_page)(struct page *);
+};
+
/* Defined in mm/debug.c: */
extern const char *migrate_reason_names[MR_TYPES];
@@ -91,13 +128,13 @@ static inline int next_demotion_node(int node)
#endif
#ifdef CONFIG_COMPACTION
-extern int PageMovable(struct page *page);
-extern void __SetPageMovable(struct page *page, struct address_space *mapping);
-extern void __ClearPageMovable(struct page *page);
+bool PageMovable(struct page *page);
+void __SetPageMovable(struct page *page, const struct movable_operations *ops);
+void __ClearPageMovable(struct page *page);
#else
-static inline int PageMovable(struct page *page) { return 0; }
+static inline bool PageMovable(struct page *page) { return false; }
static inline void __SetPageMovable(struct page *page,
- struct address_space *mapping)
+ const struct movable_operations *ops)
{
}
static inline void __ClearPageMovable(struct page *page)
@@ -110,6 +147,15 @@ static inline bool folio_test_movable(struct folio *folio)
return PageMovable(&folio->page);
}
+static inline
+const struct movable_operations *page_movable_ops(struct page *page)
+{
+ VM_BUG_ON(!__PageMovable(page));
+
+ return (const struct movable_operations *)
+ ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
+}
+
#ifdef CONFIG_NUMA_BALANCING
extern int migrate_misplaced_page(struct page *page,
struct vm_area_struct *vma, int node);