[PATCH] ARM: highmem: avoid clobbering non-page aligned memory reservations

[Ard Biesheuvel]

free_highpages() iterates over the free memblock regions in high
memory, and marks each page as available for the memory management
system. However, as it rounds the end of each region downwards, we
may end up freeing a page that is memblock_reserve()d, resulting
in memory corruption. So align the end of the range to the next
page instead.

Cc: <stable at vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
---
 arch/arm/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index a391804c7ce3..d41781cb5496 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -354,7 +354,7 @@ static void __init free_highpages(void)
 	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
 				&range_start, &range_end, NULL) {
 		unsigned long start = PHYS_PFN(range_start);
-		unsigned long end = PHYS_PFN(range_end);
+		unsigned long end = PHYS_PFN(PAGE_ALIGN(range_end));
 
 		/* Ignore complete lowmem entries */
 		if (end <= max_low)
-- 
2.17.1