mm/memory_hotplug: inline __offline_pages() into offline_pages()

Patch series "mm/memory_hotplug: online_pages()/offline_pages() cleanups", v2.

These are a bunch of cleanups for online_pages()/offline_pages() and
related code, mostly getting rid of memory hole handling that is no longer
necessary.  There is only a single walk_system_ram_range() call left in
offline_pages(), to make sure we don't have any memory holes.  I had some
of these patches lying around for a longer time but didn't have time to
polish them.

In addition, the last patch marks all pageblocks of memory to get onlined
MIGRATE_ISOLATE, so pages that have just been exposed to the buddy cannot
get allocated before onlining is complete.  Once heavy lifting is done,
the pageblocks are set to MIGRATE_MOVABLE, such that allocations are
possible.

I played with DIMMs and virtio-mem on x86-64 and didn't spot any
surprises.  I verified that the numer of isolated pageblocks is correctly
handled when onlining/offlining.

This patch (of 10):

There is only a single user, offline_pages(). Let's inline, to make
it look more similar to online_pages().

Signed-off-by: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Reviewed-by: Pankaj Gupta <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: Baoquan He <[email protected]>
Cc: Pankaj Gupta <[email protected]>
Cc: Charan Teja Reddy <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Logan Gunthorpe <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Michel Lespinasse <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Mel Gorman <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 5 insertions, 11 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 8e9e2d44cdad..ba201ab4c0e4 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1484,11 +1484,10 @@ static int count_system_ram_pages_cb(unsigned long start_pfn,
 	return 0;
 }
 
-static int __ref __offline_pages(unsigned long start_pfn,
-		  unsigned long end_pfn)
+int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 {
-	unsigned long pfn, nr_pages = 0;
-	unsigned long offlined_pages = 0;
+	const unsigned long end_pfn = start_pfn + nr_pages;
+	unsigned long pfn, system_ram_pages = 0, offlined_pages = 0;
 	int ret, node, nr_isolate_pageblock;
 	unsigned long flags;
 	struct zone *zone;
@@ -1505,9 +1504,9 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	 * memory holes PG_reserved, don't need pfn_valid() checks, and can
 	 * avoid using walk_system_ram_range() later.
 	 */
-	walk_system_ram_range(start_pfn, end_pfn - start_pfn, &nr_pages,
+	walk_system_ram_range(start_pfn, nr_pages, &system_ram_pages,
 			      count_system_ram_pages_cb);
-	if (nr_pages != end_pfn - start_pfn) {
+	if (system_ram_pages != nr_pages) {
 		ret = -EINVAL;
 		reason = "memory holes";
 		goto failed_removal;
@@ -1656,11 +1655,6 @@ failed_removal:
 	return ret;
 }
 
-int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
-{
-	return __offline_pages(start_pfn, start_pfn + nr_pages);
-}
-
 static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
 {
 	int ret = !is_memblock_offlined(mem);