From: Alexander Egorenkov egorenar@linux.ibm.com
commit 6b4b54c7ca347bcb4aa7a3cc01aa16e84ac7fbe4 upstream.
We need to preserve the values at OLDMEM_BASE and OLDMEM_SIZE which are used by zgetdump in case when kdump crashes. In that case zgetdump will attempt to read OLDMEM_BASE and OLDMEM_SIZE in order to find out where the memory range [0 - OLDMEM_SIZE] belonging to the production kernel is.
Fixes: f1a546947431 ("s390/setup: don't reserve memory that occupied decompressor's head") Cc: stable@vger.kernel.org # 5.15+ Signed-off-by: Alexander Egorenkov egorenar@linux.ibm.com Acked-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/kernel/setup.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -800,6 +800,8 @@ static void __init check_initrd(void) static void __init reserve_kernel(void) { memblock_reserve(0, STARTUP_NORMAL_OFFSET); + memblock_reserve(OLDMEM_BASE, sizeof(unsigned long)); + memblock_reserve(OLDMEM_SIZE, sizeof(unsigned long)); memblock_reserve(__amode31_base, __eamode31 - __samode31); memblock_reserve(__pa(sclp_early_sccb), EXT_SCCB_READ_SCP); memblock_reserve(__pa(_stext), _end - _stext);