Re: [PATCH] x86/mm: trivial code cleanup for memory_map_top_doown()
From: Borislav Petkov
Date: Mon Mar 13 2017 - 14:50:50 EST
On Fri, Feb 17, 2017 at 10:30:33PM +0800, Wei Yang wrote:
> In case (last_start <= step_size), start is for sure to be 0. So, it is
Well, lemme see:
[ 0.000000] memory_map_top_down: entry, [0x100000:0x7ffdf000)
[ 0.000000] memory_map_top_down: addr: 0x7fc00000, real_end: 0x7fe00000
[ 0.000000] memory_map_top_down: last_start: 0x40000000 <= step_size: 0x2000000000, start: 0x40000000
^^^^^^^^^^
It doesn't look like 0 to me.
---
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 2193799ca800..d3b02a416df3 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -506,10 +506,14 @@ static void __init memory_map_top_down(unsigned long map_start,
unsigned long addr;
unsigned long mapped_ram_size = 0;
+ pr_info("%s: entry, [0x%lx:0x%lx)\n", __func__, map_start, map_end);
+
/* xen has big range in reserved near end of ram, skip it at first.*/
addr = memblock_find_in_range(map_start, map_end, PMD_SIZE, PMD_SIZE);
real_end = addr + PMD_SIZE;
+ pr_info("%s: addr: 0x%lx, real_end: 0x%lx\n", __func__, addr, real_end);
+
/* step_size need to be small so pgt_buf from BRK could cover it */
step_size = PMD_SIZE;
max_pfn_mapped = 0; /* will get exact value next */
@@ -527,8 +531,13 @@ static void __init memory_map_top_down(unsigned long map_start,
start = round_down(last_start - 1, step_size);
if (start < map_start)
start = map_start;
- } else
+ } else {
+ pr_info("%s: last_start: 0x%lx <= step_size: 0x%lx, start: 0x%lx\n",
+ __func__, last_start, step_size, start);
+
start = map_start;
+ }
+
mapped_ram_size += init_range_memory_mapping(start,
last_start);
last_start = start;
--
Regards/Gruss,
Boris.
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