[precise][PATCHv2 1/2](upstream) mm: introduce helper function mem_init_print_info() to simplify mem_init()

[Dan Streetman]

From: Jiang Liu <liuj97 at gmail.com>

BugLink: http://bugs.launchpad.net/bugs/1622567

Backport required only context changes.  Only part of this is required
by the next patch, the get_num_physpages() function.  This patch does
contain the other part of the upstream commit, the mem_init_print_info()
function, although the next patch in this series does not require it.

Introduce helper function mem_init_print_info() to simplify mem_init()
across different architectures, which also unifies the format and
information printed.

Function mem_init_print_info() calculates memory statistics information
without walking each page, so it should be a little faster on some
architectures.

Also introduce another helper get_num_physpages() to kill the global
variable num_physpages.

Signed-off-by: Jiang Liu <jiang.liu at huawei.com>
Cc: Mel Gorman <mgorman at suse.de>
Cc: Michel Lespinasse <walken at google.com>
Cc: Rik van Riel <riel at redhat.com>
Cc: Minchan Kim <minchan at kernel.org>
Cc: Marek Szyprowski <m.szyprowski at samsung.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
(backported from commit 7ee3d4e8cd560500192d80ca84d7f15d6dee0807 upstream)
Signed-off-by: Dan Streetman <dan.streetman at canonical.com>
---
Changes since v1: added missing extern mem_init_print_info() to mm.h

 include/linux/mm.h | 14 ++++++++++++++
 mm/page_alloc.c    | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e407dba..43bd547 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1256,6 +1256,20 @@ static inline void pgtable_page_dtor(struct page *page)
 extern void free_area_init(unsigned long * zones_size);
 extern void free_area_init_node(int nid, unsigned long * zones_size,
 		unsigned long zone_start_pfn, unsigned long *zholes_size);
+
+extern void mem_init_print_info(const char *str);
+
+static inline unsigned long get_num_physpages(void)
+{
+	int nid;
+	unsigned long phys_pages = 0;
+
+	for_each_online_node(nid)
+		phys_pages += node_present_pages(nid);
+
+	return phys_pages;
+}
+
 #ifdef CONFIG_ARCH_POPULATES_NODE_MAP
 /*
  * With CONFIG_ARCH_POPULATES_NODE_MAP set, an architecture may initialise its
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 62a7fa23..c23df63 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -58,6 +58,7 @@
 #include <linux/memcontrol.h>
 #include <linux/prefetch.h>
 
+#include <asm/sections.h>
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
 #include "internal.h"
@@ -5053,6 +5054,57 @@ early_param("movablecore", cmdline_parse_movablecore);
 
 #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
 
+
+void __init mem_init_print_info(const char *str)
+{
+	unsigned long physpages, codesize, datasize, rosize, bss_size;
+	unsigned long init_code_size, init_data_size;
+
+	physpages = get_num_physpages();
+	codesize = _etext - _stext;
+	datasize = _edata - _sdata;
+	rosize = __end_rodata - __start_rodata;
+	bss_size = __bss_stop - __bss_start;
+	init_data_size = __init_end - __init_begin;
+	init_code_size = _einittext - _sinittext;
+
+	/*
+	 * Detect special cases and adjust section sizes accordingly:
+	 * 1) .init.* may be embedded into .data sections
+	 * 2) .init.text.* may be out of [__init_begin, __init_end],
+	 *    please refer to arch/tile/kernel/vmlinux.lds.S.
+	 * 3) .rodata.* may be embedded into .text or .data sections.
+	 */
+#define adj_init_size(start, end, size, pos, adj) \
+	if (start <= pos && pos < end && size > adj) \
+		size -= adj;
+
+	adj_init_size(__init_begin, __init_end, init_data_size,
+		     _sinittext, init_code_size);
+	adj_init_size(_stext, _etext, codesize, _sinittext, init_code_size);
+	adj_init_size(_sdata, _edata, datasize, __init_begin, init_data_size);
+	adj_init_size(_stext, _etext, codesize, __start_rodata, rosize);
+	adj_init_size(_sdata, _edata, datasize, __start_rodata, rosize);
+
+#undef	adj_init_size
+
+	printk("Memory: %luK/%luK available "
+	       "(%luK kernel code, %luK rwdata, %luK rodata, "
+	       "%luK init, %luK bss, %luK reserved"
+#ifdef	CONFIG_HIGHMEM
+	       ", %luK highmem"
+#endif
+	       "%s%s)\n",
+	       nr_free_pages() << (PAGE_SHIFT-10), physpages << (PAGE_SHIFT-10),
+	       codesize >> 10, datasize >> 10, rosize >> 10,
+	       (init_data_size + init_code_size) >> 10, bss_size >> 10,
+	       (physpages - totalram_pages) << (PAGE_SHIFT-10),
+#ifdef	CONFIG_HIGHMEM
+	       totalhigh_pages << (PAGE_SHIFT-10),
+#endif
+	       str ? ", " : "", str ? str : "");
+}
+
 /**
  * set_dma_reserve - set the specified number of pages reserved in the first zone
  * @new_dma_reserve: The number of pages to mark reserved
-- 
2.7.4