[PATCH] mm, memory_hotplug: consider offline memblocks removable

[Michal Hocko]

is_pageblock_removable_nolock relies on having zone association to
examine all the page blocks to check whether they are movable or free.
This is just wasting of cycles when the memblock is offline. Later patch
in the series will also change the time when the page is associated with
a zone so we let's bail out early if the memblock is offline.

Reported-by: Igor Mammedov <imammedo@xxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
 drivers/base/memory.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 9677b6b711b0..0c29ec5598ea 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -128,6 +128,9 @@ static ssize_t show_mem_removable(struct device *dev,
 	int ret = 1;
 	struct memory_block *mem = to_memory_block(dev);
 
+	if (mem->stat != MEM_ONLINE)
+		goto out;
+
 	for (i = 0; i < sections_per_block; i++) {
 		if (!present_section_nr(mem->start_section_nr + i))
 			continue;
@@ -135,6 +138,7 @@ static ssize_t show_mem_removable(struct device *dev,
 		ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
 	}
 
+out:
 	return sprintf(buf, "%d\n", ret);
 }
 
-- 
2.11.0


-- 
Michal Hocko
SUSE Labs