[PATCH v6] mm/pgmap: Use correct alignment when looking at first pfn from a region

Aneesh Kumar K.V
2019-09-17T15:31:48Z

vmem_altmap_offset() adjust the section aligned base_pfn offset.
So we need to make sure we account for the same when computing base_pfn.

ie, for altmap_valid case, our pfn_first should be:

pfn_first = altmap->base_pfn + vmem_altmap_offset(altmap);

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
* changes from v5
* update commit subject and use linux-mm for merge

mm/memremap.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/mm/memremap.c b/mm/memremap.c
index ed70c4e8e52a..233908d7df75 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -54,8 +54,16 @@ static void pgmap_array_delete(struct resource *res)

static unsigned long pfn_first(struct dev_pagemap *pgmap)
{
- return PHYS_PFN(pgmap->res.start) +
- vmem_altmap_offset(pgmap_altmap(pgmap));
+ const struct resource *res = &pgmap->res;
+ struct vmem_altmap *altmap = pgmap_altmap(pgmap);
+ unsigned long pfn;
+
+ if (altmap) {
+ pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
+ } else
+ pfn = PHYS_PFN(res->start);
+
+ return pfn;
}

static unsigned long pfn_end(struct dev_pagemap *pgmap)
--
2.21.0