linux-kernel - [PATCH] sparc32: Limit memblock allocation to low memory

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Date:   Thu,  4 Feb 2021 17:20:53 +0100
From:   Andreas Larsson <andreas@...sler.com>
To:     David Miller <davem@...emloft.net>, sparclinux@...r.kernel.org
Cc:     Mike Rapoport <rppt@...ux.ibm.com>,
        Sam Ravnborg <sam@...nborg.org>, linux-kernel@...r.kernel.org,
        software@...sler.com
Subject: [PATCH] sparc32: Limit memblock allocation to low memory

Commit cca079ef8ac29a7c02192d2bad2ffe4c0c5ffdd0 changed sparc32 to use
memblocks instead of bootmem, but also made high memory available via
memblock allocation which does work together with e.g. phys_to_virt and
leads to crashes.

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

Signed-off-by: Andreas Larsson <andreas@...sler.com>
---
 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 eb2946b1df8a..6139c5700ccc 100644
--- a/arch/sparc/mm/init_32.c
+++ b/arch/sparc/mm/init_32.c
@@ -197,6 +197,9 @@ unsigned long __init bootmem_init(unsigned long *pages_avail)
 	size = memblock_phys_mem_size() - memblock_reserved_size();
 	*pages_avail = (size >> PAGE_SHIFT) - high_pages;
 
+	/* Only allow low memory to be allocated via memblock allocation */
+	memblock_set_current_limit(max_low_pfn << PAGE_SHIFT);
+
 	return max_pfn;
 }
 
-- 
2.17.1