s390/boot: Do not force vmemmap to start at MAX_PHYSMEM_BITS

vmemmap is forcefully set to start at MAX_PHYSMEM_BITS at most.
That could be needed in the past to limit ident_map_size to
MAX_PHYSMEM_BITS. However since commit 75eba6ec0de1 ("s390:
unify identity mapping limits handling") ident_map_size is
limited in setup_ident_map_size() function, which is called
earlier.

Another reason to limit vmemmap start to MAX_PHYSMEM_BITS is
because it was returned by arch_get_mappable_range() as the
maximum mappable physical address. Since commit f641679dfe55
("s390/mm: rework arch_get_mappable_range() callback") that
is not required anymore.

As result, there is no neccessity to limit vmemmap starting
address with MAX_PHYSMEM_BITS.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 6cf8931..bb5d26f 100644 (file)
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -313,9 +313,8 @@ static unsigned long setup_kernel_memory_layout(void)
        pages = SECTION_ALIGN_UP(pages);
        /* keep vmemmap_start aligned to a top level region table entry */
        vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size);
-       vmemmap_start = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS);
-       /* maximum mappable address as seen by arch_get_mappable_range() */
-       max_mappable = vmemmap_start;
+       /* maximum address for which linear mapping could be created (DCSS, memory) */
+       max_mappable = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS);
        /* make sure identity map doesn't overlay with vmemmap */
        ident_map_size = min(ident_map_size, vmemmap_start);
        vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page);