s390/mem_detect: rely on diag260() if sclp_early_get_memsize() fails

[ Upstream commit 5966bd7fef1d7662c1250f23982e7c5a0120aa6e ]

In case sclp_early_get_memsize() fails but diag260() succeeds make sure
some sane value is returned. This error scenario is highly unlikely,
but this change makes system able to boot in such case.

Suggested-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Stable-dep-of: 2db7e7c4b86f ("s390/boot: fix mem_detect extended area allocation")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/s390/boot/mem_detect.c b/arch/s390/boot/mem_detect.c
index 0a5821ef4f1fd74390fbbebef5540d59c1f069a5..41792a3a5e36468c5ceec276dcdd908de8356827 100644 (file)
--- a/arch/s390/boot/mem_detect.c
+++ b/arch/s390/boot/mem_detect.c
@@ -176,7 +176,7 @@ unsigned long detect_memory(void)
 
        if (!diag260()) {
                mem_detect.info_source = MEM_DETECT_DIAG260;
-               return max_physmem_end;
+               return max_physmem_end ?: get_mem_detect_end();
        }
 
        if (max_physmem_end) {