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-rw-r--r--block/bio.c2
-rw-r--r--include/linux/mmzone.h24
2 files changed, 26 insertions, 0 deletions
diff --git a/block/bio.c b/block/bio.c
index 57c2f327225b..c7a124294828 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -863,6 +863,8 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
return false;
if (xen_domain() && !xen_biovec_phys_mergeable(bv, page))
return false;
+ if (!zone_device_pages_have_same_pgmap(bv->bv_page, page))
+ return false;
*same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
if (*same_page)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 5f74891556f3..9c49ec5d0e25 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)