From: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx> Currently it is possible to set the crash_size via the sysfs /sys/kernel/kexec_crash_size even if no crash kernel memory has been defined with the "crashkernel" parameter. In this case "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0. Unfortunately resource_size(&crashk_res) returns 1 in this case. This breaks the s390 implementation of crash_(un)map_reserved_pages(). To fix the problem the correct "old_size" is now calculated in crash_shrink_memory(). "old_size is set to "0" if crashk_res is not initialized. With this change crash_shrink_memory() will do nothing, when "crashk_res" is not initialized. It will return "0" for "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for "echo [not zero] > /sys/kernel/kexec_crash_size". Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com> --- kernel/kexec.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran int crash_shrink_memory(unsigned long new_size) { int ret = 0; - unsigned long start, end; + unsigned long start, end, old_size; mutex_lock(&kexec_mutex); @@ -1141,10 +1141,10 @@ int crash_shrink_memory(unsigned long ne } start = crashk_res.start; end = crashk_res.end; - - if (new_size >= end - start + 1) { + old_size = (end == 0) ? 0 : end - start + 1; + if (new_size >= old_size) { ret = -EINVAL; - if (new_size == end - start + 1) + if (new_size == old_size) ret = 0; goto unlock; }