[PATCH] MIPS: mm: Add check for highmem before removing memory block

[Kyle Hendry <kylehendrydev@gmail.com>]

If a device has less physical memory than the highmem threshold
bootmem_init() doesn't set highstart_pfn. This results in highmem_init()
wrongly disabling the entire memory range if the cpu doesn't support
highmem. Add a check that highstart_pfn is non zero before removing the
highmem block.

Signed-off-by: Kyle Hendry <kylehendrydev@gmail.com>
---
 arch/mips/mm/init.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 1c07ca84ee21..352718e43f69 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -426,10 +426,11 @@ static inline void __init highmem_init(void)
 	unsigned long tmp;
 
 	/*
-	 * If CPU cannot support HIGHMEM discard the memory above highstart_pfn
+	 * If CPU cannot support HIGHMEM discard any memory above highstart_pfn
 	 */
 	if (cpu_has_dc_aliases) {
-		memblock_remove(PFN_PHYS(highstart_pfn), -1);
+		if (highstart_pfn)
+			memblock_remove(PFN_PHYS(highstart_pfn), -1);
 		return;
 	}
 
-- 
2.43.0