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-rw-r--r--include/linux/mmzone.h26
1 files changed, 25 insertions, 1 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 5f74891556f3..cd28a100d9e4 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -986,6 +986,25 @@ static inline bool is_zone_device_page(const struct page *page)
{
return page_zonenum(page) == ZONE_DEVICE;
}
+
+/*
+ * Consecutive zone device pages should not be merged into the same sgl
+ * or bvec segment with other types of pages or if they belong to different
+ * pgmaps. Otherwise getting the pgmap of a given segment is not possible
+ * without scanning the entire segment. This helper returns true either if
+ * both pages are not zone device pages or both pages are zone device pages
+ * with the same pgmap.
+ */
+static inline bool zone_device_pages_have_same_pgmap(const struct page *a,
+ const struct page *b)
+{
+ if (is_zone_device_page(a) != is_zone_device_page(b))
+ return false;
+ if (!is_zone_device_page(a))
+ return true;
+ return a->pgmap == b->pgmap;
+}
+
extern void memmap_init_zone_device(struct zone *, unsigned long,
unsigned long, struct dev_pagemap *);
#else
@@ -993,6 +1012,11 @@ static inline bool is_zone_device_page(const struct page *page)
{
return false;
}
+static inline bool zone_device_pages_have_same_pgmap(const struct page *a,
+ const struct page *b)
+{
+ return true;
+}
#endif
static inline bool folio_is_zone_device(const struct folio *folio)
@@ -1200,7 +1224,7 @@ typedef struct pglist_data {
/* start time in ms of current promote threshold adjustment period */
unsigned int nbp_th_start;
/*
- * number of promote candidate pages at stat time of current promote
+ * number of promote candidate pages at start time of current promote
* threshold adjustment period
*/
unsigned long nbp_th_nr_cand;