[PATCH V2 2/3] MIPS: Reserve extra memory for crash dump

[Huacai Chen]

Traditionally, MIPS's contiguous low memory can be as less as 256M, so
crashkernel=X at Y may be unable to large enough in some cases. Moreover,
for the "multi numa node + sparse memory model" case, it is attempt to
allocate section_mem_maps on every node. Thus, if the total memory of a
node is more than 1GB, we reserve the top 128MB for the crash kernel.

Signed-off-by: Huacai Chen <chenhc at lemote.com>
---
 arch/mips/kernel/setup.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index e2804a2..90d4a2e 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -29,6 +29,7 @@
 #include <linux/of_fdt.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/dmi.h>
+#include <linux/crash_dump.h>
 
 #include <asm/addrspace.h>
 #include <asm/bootinfo.h>
@@ -55,6 +56,10 @@ EXPORT_SYMBOL(cpu_data);
 struct screen_info screen_info;
 #endif
 
+#ifdef CONFIG_CRASH_DUMP
+static phys_addr_t crashmem_start, crashmem_size;
+#endif
+
 /*
  * Setup information
  *
@@ -404,6 +409,13 @@ static int __init early_parse_mem(char *p)
 
 	add_memory_region(start, size, BOOT_MEM_RAM);
 
+#ifdef CONFIG_CRASH_DUMP
+	if (start && size) {
+		crashmem_start = start;
+		crashmem_size = size;
+	}
+#endif
+
 	return 0;
 }
 early_param("mem", early_parse_mem);
@@ -642,6 +654,48 @@ static void __init bootcmdline_init(void)
 		bootcmdline_append(builtin_cmdline, COMMAND_LINE_SIZE);
 }
 
+/* Traditionally, MIPS's contiguous low memory is 256M, so crashkernel=X at Y is
+ * unable to be large enough in some cases. Thus, if the total memory of a node
+ * is more than 1GB, we reserve the top 128MB for the crash kernel */
+static void reserve_crashm_region(int node, unsigned long s0, unsigned long e0)
+{
+#ifdef CONFIG_KEXEC
+	if (crashk_res.start == crashk_res.end)
+		return;
+
+	if ((e0 - s0) <= (SZ_1G >> PAGE_SHIFT))
+		return;
+
+	s0 = e0 - (SZ_128M >> PAGE_SHIFT);
+
+	memblock_reserve(PFN_PHYS(s0), (e0 - s0) << PAGE_SHIFT);
+#endif
+}
+
+static void reserve_oldmem_region(int node, unsigned long s0, unsigned long e0)
+{
+#ifdef CONFIG_CRASH_DUMP
+	unsigned long s1, e1;
+
+	if (!is_kdump_kernel())
+		return;
+
+	if ((e0 - s0) > (SZ_1G >> PAGE_SHIFT))
+		e0 = e0 - (SZ_128M >> PAGE_SHIFT);
+
+	/* crashmem_start is crashk_res reserved by primary kernel */
+	s1 = PFN_UP(crashmem_start);
+	e1 = PFN_DOWN(crashmem_start + crashmem_size);
+
+	if (node == 0) {
+		memblock_reserve(PFN_PHYS(s0), (s1 - s0) << PAGE_SHIFT);
+		memblock_reserve(PFN_PHYS(e1), (e0 - e1) << PAGE_SHIFT);
+	} else {
+		memblock_reserve(PFN_PHYS(s0), (e0 - s0) << PAGE_SHIFT);
+	}
+#endif
+}
+
 /*
  * arch_mem_init - initialize memory management subsystem
  *
@@ -666,6 +720,9 @@ static void __init bootcmdline_init(void)
  */
 static void __init arch_mem_init(char **cmdline_p)
 {
+	unsigned int node;
+	unsigned long start_pfn, end_pfn;
+
 	/* call board setup routine */
 	plat_mem_setup();
 	memblock_set_bottom_up(true);
@@ -711,6 +768,12 @@ static void __init arch_mem_init(char **cmdline_p)
 	if (crashk_res.start != crashk_res.end)
 		memblock_reserve(crashk_res.start, resource_size(&crashk_res));
 #endif
+	for_each_online_node(node) {
+		get_pfn_range_for_nid(node, &start_pfn, &end_pfn);
+		reserve_crashm_region(node, start_pfn, end_pfn);
+		reserve_oldmem_region(node, start_pfn, end_pfn);
+	}
+
 	device_tree_init();
 
 	/*
-- 
2.7.0