sparse-vmemmap: specify vmemmap population range in bytes

The sparse code, when asking the architecture to populate the vmemmap,
specifies the section range as a starting page and a number of pages.

This is an awkward interface, because none of the arch-specific code
actually thinks of the range in terms of 'struct page' units and always
translates it to bytes first.

In addition, later patches mix huge page and regular page backing for
the vmemmap.  For this, they need to call vmemmap_populate_basepages()
on sub-section ranges with PAGE_SIZE and PMD_SIZE in mind.  But these
are not necessarily multiples of the 'struct page' size and so this unit
is too coarse.

Just translate the section range into bytes once in the generic sparse
code, then pass byte ranges down the stack.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Bernhard Schmidt <Bernhard.Schmidt@lrz.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Tested-by: David S. Miller <davem@davemloft.net>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 7 deletions

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 22b7e18e9dea..27eeab3be757 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -147,11 +147,10 @@ pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
         return pgd;
 }
 
-int __meminit vmemmap_populate_basepages(struct page *start_page,
-                                                unsigned long size, int node)
+int __meminit vmemmap_populate_basepages(unsigned long start,
+                                         unsigned long end, int node)
 {
-        unsigned long addr = (unsigned long)start_page;
-        unsigned long end = (unsigned long)(start_page + size);
+        unsigned long addr = start;
         pgd_t *pgd;
         pud_t *pud;
         pmd_t *pmd;
@@ -178,9 +177,15 @@ int __meminit vmemmap_populate_basepages(struct page *start_page,
 
 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
 {
-        struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
-        int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
-        if (error)
+        unsigned long start;
+        unsigned long end;
+        struct page *map;
+
+        map = pfn_to_page(pnum * PAGES_PER_SECTION);
+        start = (unsigned long)map;
+        end = (unsigned long)(map + PAGES_PER_SECTION);
+
+        if (vmemmap_populate(start, end, nid))
                 return NULL;
 
         return map;