[PATCH] mm/hmm: Fix calcuation of start address for unaddressable memory

[Balbir Singh <bsingharora@gmail.com>]

The code used iomem_resource.end which is an odd number and hence
the calculation then moves on to addr - size + 1. When the minimum
is (1ULL << MAX_PHYSMEM_BITS), the calculation of start is broken.
This patch changes the calculation so that addr is on the start
of a PA_SECTION_SIZE boundary

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 mm/hmm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index 34e1325..cc6d25c 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -1022,7 +1022,8 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
 		goto error_devm_add_action;
 
 	size = ALIGN(size, PA_SECTION_SIZE);
-	addr = min((unsigned long)iomem_resource.end, 1UL << MAX_PHYSMEM_BITS);
+	addr = min((unsigned long)iomem_resource.end,
+					(1UL << MAX_PHYSMEM_BITS) - 1);
 	addr = addr - size + 1UL;
 
 	/*
-- 
2.9.4

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