[PATCH] powerpc/crashkernel: take mem option into account

[Pingfan Liu]

'mem=" option is an easy way to put high pressure on memory during some
test. Hence in stead of total mem, the effective usable memory size should
be considered when reserving mem for crashkernel. Otherwise the boot up may
experience oom issue.

E.g passing
crashkernel="2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G", and
mem=5G on a 256G machine.

Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
Cc: Hari Bathini <hbathini at linux.ibm.com>
Cc: Michael Ellerman <mpe at ellerman.id.au>
To: linuxppc-dev at lists.ozlabs.org
---
v1 -> v2: fix the printk info about the total mem
 arch/powerpc/kernel/machine_kexec.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
index c4ed328..eec96dc 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -114,11 +114,12 @@ void machine_kexec(struct kimage *image)
 
 void __init reserve_crashkernel(void)
 {
-	unsigned long long crash_size, crash_base;
+	unsigned long long crash_size, crash_base, total_mem_sz;
 	int ret;
 
+	total_mem_sz = memory_limit ? memory_limit : memblock_phys_mem_size();
 	/* use common parsing */
-	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
+	ret = parse_crashkernel(boot_command_line, total_mem_sz,
 			&crash_size, &crash_base);
 	if (ret == 0 && crash_size > 0) {
 		crashk_res.start = crash_base;
@@ -185,7 +186,7 @@ void __init reserve_crashkernel(void)
 			"for crashkernel (System RAM: %ldMB)\n",
 			(unsigned long)(crash_size >> 20),
 			(unsigned long)(crashk_res.start >> 20),
-			(unsigned long)(memblock_phys_mem_size() >> 20));
+			(unsigned long)(total_mem_sz >> 20));
 
 	if (!memblock_is_region_memory(crashk_res.start, crash_size) ||
 	    memblock_reserve(crashk_res.start, crash_size)) {
-- 
2.7.5