Commit c34a6905 authored May 10, 2016 by Heiko Carstens Committed by Martin Schwidefsky May 11, 2016

s390/vmem: fix identity mapping



The identity mapping is suboptimal for the last 2GB frame. The mapping
will be established with a mix of 4KB and 1MB mappings instead of a
single 2GB mapping.

This happens because of a off-by-one bug introduced with
commit 50be6345 ("s390/mm: Convert bootmem to memblock").

Currently the identity mapping looks like this:

0x0000000080000000-0x0000000180000000        4G PUD RW
0x0000000180000000-0x00000001fff00000     2047M PMD RW
0x00000001fff00000-0x0000000200000000        1M PTE RW

With the bug fixed it looks like this:

0x0000000080000000-0x0000000200000000        6G PUD RW

Fixes: 50be6345 ("s390/mm: Convert bootmem to memblock")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent ca21872e

arch/s390/mm/vmem.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -370,7 +370,7 @@ void __init vmem_map_init(void)
		ro_end = (unsigned long)&_eshared & PAGE_MASK;
		for_each_memblock(memory, reg) {
		start = reg->base;
		end = reg->base + reg->size - 1;
		end = reg->base + reg->size;
		if (start >= ro_end \|\| end <= ro_start)
		vmem_add_mem(start, end - start, 0);
		else if (start >= ro_start && end <= ro_end)

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