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Subject[PATCH v2 5/7] mm,memory_hotplug: Enforce pageblock alignment when memmap_on_memory
Date
Many places expects us to pass a pageblock aligned range.
E.g: memmap_init_zone() needs a pageblock aligned range in order
to set the proper migrate type for it.
online_pages() needs to operate on a pageblock aligned range for
isolation purposes.

Make sure we disable the feature in case we cannot guarantee the
right alignment.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
mm/memory_hotplug.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d3fb036d33fd..1a4d5dd1a2c8 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -56,12 +56,16 @@ static int memmap_on_memory_show(char *buffer, const struct kernel_param *kp)
static __meminit int memmap_on_memory_store(const char *val,
const struct kernel_param *kp)
{
+ unsigned long pageblock_size = PFN_PHYS(pageblock_nr_pages);
+
/*
* Fail silently in case we cannot enable it due to system constraints.
* User can always check whether it is enabled or not via /sys/module.
*/
if (!IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE) ||
- (PMD_SIZE % sizeof(struct page)))
+ (PMD_SIZE % sizeof(struct page)) ||
+ !(MIN_MEMORY_BLOCK_SIZE - PMD_SIZE) ||
+ !(MIN_MEMORY_BLOCK_SIZE - PMD_SIZE) % pageblock_size)
return 0;

return param_set_bool(val, kp);
--
2.16.3
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