Re: [PATCH AUTOSEL 4.14 06/13] sparc32: Limit memblock allocation to low memory

From: Andreas Larsson <andreas@gaisler.com>

[ Upstream commit bda166930c37604ffa93f2425426af6921ec575a ]

Commit cca079ef8ac29a7c02192d2bad2ffe4c0c5ffdd0 changed sparc32 to use
memblocks instead of bootmem, but also made high memory available via
memblock allocation which does not work together with e.g. phys_to_virt
and can lead to kernel panic.

This changes back to only low memory being allocatable in the early
stages, now using memblock allocation.

Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Acked-by: Mike Rapoport <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
  arch/sparc/mm/init_32.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/arch/sparc/mm/init_32.c b/arch/sparc/mm/init_32.c
index 95fe4f081ba3..372a4f08ddf8 100644
--- a/arch/sparc/mm/init_32.c
+++ b/arch/sparc/mm/init_32.c

@@ -230,6 +230,9 @@ unsigned long __init bootmem_init(unsigned long *pages_avail)
  	reserve_bootmem((bootmap_pfn << PAGE_SHIFT), size, BOOTMEM_DEFAULT);
  	*pages_avail -= PAGE_ALIGN(size) >> PAGE_SHIFT;
  
+	/* Only allow low memory to be allocated via memblock allocation */
+	memblock_set_current_limit(max_low_pfn << PAGE_SHIFT);
+
  	return max_pfn;
  }