[PATCH] ARM: mm: Fix the memblock allocation for LPAE machines

Santosh Shilimkar santosh.shilimkar at ti.com
Sat Feb 1 15:14:47 EST 2014

Commit ad6492b8 added much needed memblock_virt_alloc_low() and further
commit 07bacb3 {memblock, bootmem: restore goal for alloc_low} fixed the
issue with low memory limit thansk to Yinghai. But even after all these fixes,
there is still one case where the limit check done with ARCH_LOW_ADDRESS_LIMIT
for low memory fails. Russell pointed out the issue with 32 bit LPAE machines
in below thread.

Since on some LPAE machines where memory start address is beyond 4GB,
the low memory marker in memblock will be set to default
ARCH_LOW_ADDRESS_LIMIT which is wrong. We can fix this by letting
architectures set the ARCH_LOW_ADDRESS_LIMIT using another export
similar to memblock_set_current_limit() but am not sure whether
its worth the trouble. Tell me if you think otherwise.

Rather am just trying to fix that one broken case using memblock_virt_alloc()
in setup code since the memblock.current_limit is updated appropriately
makes it work on all ARM 32 bit machines.

Cc: Yinghai Lu <yinghai at kernel.org>
Cc: Russell King <linux at arm.linux.org.uk>
Cc: Strashko, Grygorii <grygorii.strashko at ti.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
 arch/arm/kernel/setup.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index b0df976..1e8b030 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -731,7 +731,7 @@ static void __init request_standard_resources(const struct machine_desc *mdesc)
 	kernel_data.end     = virt_to_phys(_end - 1);
 	for_each_memblock(memory, region) {
-		res = memblock_virt_alloc_low(sizeof(*res), 0);
+		res = memblock_virt_alloc(sizeof(*res), 0);
 		res->name  = "System RAM";
 		res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
 		res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;

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