generic hotplug friendly page_is_ram()

---
 arch/mips/mm/init.c    |    2 +-
 arch/score/mm/init.c   |    2 +-
 include/linux/ioport.h |    2 ++
 kernel/resource.c      |   11 +++++++++++
 4 files changed, 15 insertions(+), 2 deletions(-)

kernel/resource.c +11 -0

@@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long 
 
 #endif
 
+#define PAGE_IS_RAM	24
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+	return PAGE_IS_RAM;
+}
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+	return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+
 /*
  * Find empty slot in the resource tree given range and alignment.
  */

include/linux/ioport.h +2 -0

@@ -191,5 +191,7 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 
+extern int page_is_ram(unsigned long pfn);
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */

arch/score/mm/init.c +1 -1

@@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
 		return 1;

arch/mips/mm/init.c +1 -1

@@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long 
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	int i;

KAMEZAWA Hiroyuki

Reviewed-by Reviewed-by on v1 1/3

2010-01-22 04:13 UTC #2 lore raw

Re: [PATCH 1/3] resources: introduce generic page_is_ram()

Quoted 5 lines · On Fri, 22 Jan 2010 11:21:03 +0800 Wu Fengguang <[email protected]> wrote:

It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().
The static verions in MIPS and SCORE are also made global.

Quoted 8 lines

CC Chen Liqin <[email protected]>
CC Lennox Wu <[email protected]>
CC Ralf Baechle <[email protected]>
CC Am辿rico Wang <[email protected]>
CC [email protected]
CC KAMEZAWA Hiroyuki <[email protected]>
CC Yinghai Lu <[email protected]>
Signed-off-by Wu Fengguang <[email protected]>

Maybe adding comment like this is good for reviewers..

"This page_is_ram() returns true if specified address is registered
as System RAM in io_resource list."

AFAIK, this "System RAM" information has been used for kdump to grab valid memory area and seems good for the kernel itself.

Thanks,
-Kame

Quoted 62 lines

---
 arch/mips/mm/init.c    |    2 +-
 arch/score/mm/init.c   |    2 +-
 include/linux/ioport.h |    2 ++
 kernel/resource.c      |   11 +++++++++++
 4 files changed, 15 insertions(+), 2 deletions(-)

kernel/resource.c +11 -0

@@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long 
 
 #endif
 
+#define PAGE_IS_RAM	24
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+	return PAGE_IS_RAM;
+}
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+	return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+
 /*
  * Find empty slot in the resource tree given range and alignment.
  */

include/linux/ioport.h +2 -0

@@ -191,5 +191,7 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 
+extern int page_is_ram(unsigned long pfn);
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */

arch/score/mm/init.c +1 -1

@@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
 		return 1;

arch/mips/mm/init.c +1 -1

@@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long 
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	int i;

Wu Fengguang

author

2010-01-22 04:20 UTC #3 lore raw

PATCH v3 1/3 resources: introduce generic page_is_ram()

Quoted 19 lines · KAMEZAWA Hiroyuki

Quoted 5 lines · On Fri, 22 Jan 2010 11:21:03 +0800 Wu Fengguang <[email protected]> wrote:
It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().
The static verions in MIPS and SCORE are also made global.
Quoted 8 lines
CC Chen Liqin <[email protected]>
CC Lennox Wu <[email protected]>
CC Ralf Baechle <[email protected]>
CC Am辿rico Wang <[email protected]>
CC [email protected]
CC KAMEZAWA Hiroyuki <[email protected]>
CC Yinghai Lu <[email protected]>
Signed-off-by Wu Fengguang <[email protected]>
Reviewed-by KAMEZAWA Hiroyuki <[email protected]>

Quoted 7 lines

Maybe adding comment like this is good for reviewers..
"This page_is_ram() returns true if specified address is registered
as System RAM in io_resource list."
AFAIK, this "System RAM" information has been used for kdump to grab valid memory area and seems good for the kernel itself.

Thanks! Patch updated as follows.

---
resources: introduce generic page_is_ram()

It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().

The static verions in MIPS and SCORE are also made global.

v3: add comment (KAMEZAWA Hiroyuki)
v2: add PAGE_IS_RAM macro (Américo Wang)

CC Chen Liqin <[email protected]>

CC Lennox Wu <[email protected]>

CC Ralf Baechle <[email protected]>

CC Américo Wang <[email protected]>

CC [email protected]

CC Yinghai Lu <[email protected]>

---
 arch/mips/mm/init.c    |    2 +-
 arch/score/mm/init.c   |    2 +-
 include/linux/ioport.h |    2 ++
 kernel/resource.c      |   15 +++++++++++++++
 4 files changed, 19 insertions(+), 2 deletions(-)

kernel/resource.c +15 -0

@@ -327,6 +327,21 @@ int walk_system_ram_range(unsigned long 
 
 #endif
 
+#define PAGE_IS_RAM	24
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+	return PAGE_IS_RAM;
+}
+/*
+ * This generic page_is_ram() returns true if specified address is
+ * registered as "System RAM" in iomem_resource list.
+ */
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+	return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+
 /*
  * Find empty slot in the resource tree given range and alignment.
  */

include/linux/ioport.h +2 -0

@@ -191,5 +191,7 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 
+extern int page_is_ram(unsigned long pfn);
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */

arch/score/mm/init.c +1 -1

@@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
 		return 1;

arch/mips/mm/init.c +1 -1

@@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long 
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	int i;

Xiaotian Feng

2010-01-22 05:15 UTC #4 lore raw

Re: [PATCH 1/3] resources: introduce generic page_is_ram()

Quoted 27 lines · Wu Fengguang

It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().
The static verions in MIPS and SCORE are also made global.
CC Chen Liqin <[email protected]>
CC Lennox Wu <[email protected]>
CC Ralf Baechle <[email protected]>
CC Américo Wang <[email protected]>
CC [email protected]
CC KAMEZAWA Hiroyuki <[email protected]>
CC Yinghai Lu <[email protected]>
Signed-off-by Wu Fengguang <[email protected]>
---
arch/mips/mm/init.c | 2 +-
arch/score/mm/init.c | 2 +-
include/linux/ioport.h | 2 ++
kernel/resource.c | 11 +++++++++++
 4 files changed, 15 insertions(+), 2 deletions(-)
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +1 -0
@@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long
 
  #endif
 
+#define PAGE_IS_RAM    24

kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 int walk_system_ram_range(unsigned long · line 340

Quoted 10 lines

kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +10 -0
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+       return PAGE_IS_RAM;
+}
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+       return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+

I'm not sure, but any build test for powerpc/mips/score? walk_system_ram_range is defined when CONFIG_ARCH_HAS_WALK_MEMORY is not set. Is it safe when CONFIG_ARCH_HAS_WALK_MEMORY is set for some powerpc archs?

Quoted 43 lines

kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +0 -0
  /*
  * Find empty slot in the resource tree given range and alignment.
  */
include/linux/ioport.h 2010-01-22 11:20:35.000000000 +0800 renamed from include/linux/ioport.h 2010-01-22 11:20:34.000000000 +0800 +2 -0
@@ -191,5 +191,7 @@ extern int
  walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
                void *arg, int (*func)(unsigned long, unsigned long, void *));
 
+extern int page_is_ram(unsigned long pfn);
+
  #endif /* __ASSEMBLY__ */
  #endif /* _LINUX_IOPORT_H */
arch/score/mm/init.c 2010-01-22 11:20:35.000000000 +0800 renamed from arch/score/mm/init.c 2010-01-22 11:20:34.000000000 +0800 +1 -1
@@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
  }
 
  #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
  {
        if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
                return 1;
arch/mips/mm/init.c 2010-01-22 11:20:35.000000000 +0800 renamed from arch/mips/mm/init.c 2010-01-22 11:20:34.000000000 +0800 +1 -2
@@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long
  }
 
  #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
  {
        int i;
 
 
 
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Wu Fengguang

author

2010-01-22 05:37 UTC #5 lore raw

Re: [PATCH 1/3] resources: introduce generic page_is_ram()

Quoted 27 lines · Xiaotian Feng

Quoted 26 lines · Wu Fengguang
It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().
The static verions in MIPS and SCORE are also made global.
CC Chen Liqin <[email protected]>
CC Lennox Wu <[email protected]>
CC Ralf Baechle <[email protected]>
CC Américo Wang <[email protected]>
CC [email protected]
CC KAMEZAWA Hiroyuki <[email protected]>
CC Yinghai Lu <[email protected]>
Signed-off-by Wu Fengguang <[email protected]>
---
arch/mips/mm/init.c | 2 +-
arch/score/mm/init.c | 2 +-
include/linux/ioport.h | 2 ++
kernel/resource.c | 11 +++++++++++
 4 files changed, 15 insertions(+), 2 deletions(-)
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +0 -0
@@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long
 
  #endif
 

Quoted 13 lines

kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 int walk_system_ram_range(unsigned long · line 340
Quoted 11 lines
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +11 -0
+#define PAGE_IS_RAM    24
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+       return PAGE_IS_RAM;
+}
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+       return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+
I'm not sure, but any build test for powerpc/mips/score?

Sorry, no build tests yet:

/bin/sh: score-linux-gcc: command not found

I just make the mips/score page_is_ram() non-static and assume that will make it compile.

Quoted 2 lines

walk_system_ram_range is defined when CONFIG_ARCH_HAS_WALK_MEMORY is not set. Is it safe when CONFIG_ARCH_HAS_WALK_MEMORY is set for some powerpc archs?

Good question. Grep shows that CONFIG_ARCH_HAS_WALK_MEMORY is only defined for powerpc, and it has its own page_is_ram() as well as walk_system_ram_range().

walk_system_ram_range() must be defined somewhere because it is expected to be generic routine: exported and called from both in-kernel and out-of-tree code.

Thanks,
Fengguang

Xiaotian Feng

2010-01-22 05:50 UTC #6 lore raw

Re: [PATCH 1/3] resources: introduce generic page_is_ram()

Quoted 52 lines · Wu Fengguang

Quoted 27 lines · Xiaotian Feng
Quoted 26 lines · Wu Fengguang
It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().
The static verions in MIPS and SCORE are also made global.
CC Chen Liqin <[email protected]>
CC Lennox Wu <[email protected]>
CC Ralf Baechle <[email protected]>
CC Américo Wang <[email protected]>
CC [email protected]
CC KAMEZAWA Hiroyuki <[email protected]>
CC Yinghai Lu <[email protected]>
Signed-off-by Wu Fengguang <[email protected]>
---
arch/mips/mm/init.c | 2 +-
arch/score/mm/init.c | 2 +-
include/linux/ioport.h | 2 ++
kernel/resource.c | 11 +++++++++++
 4 files changed, 15 insertions(+), 2 deletions(-)
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +0 -0
@@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long
 
  #endif
 
Quoted 13 lines
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 int walk_system_ram_range(unsigned long · line 340
Quoted 11 lines
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +11 -0
+#define PAGE_IS_RAM    24
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+       return PAGE_IS_RAM;
+}
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+       return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+
I'm not sure, but any build test for powerpc/mips/score?
Sorry, no build tests yet:
/bin/sh: score-linux-gcc: command not found
I just make the mips/score page_is_ram() non-static and assume that will make it compile.
Quoted 2 lines
walk_system_ram_range is defined when CONFIG_ARCH_HAS_WALK_MEMORY is not set. Is it safe when CONFIG_ARCH_HAS_WALK_MEMORY is set for some powerpc archs?

Quoted 8 lines

Good question. Grep shows that CONFIG_ARCH_HAS_WALK_MEMORY is only defined for powerpc, and it has its own page_is_ram() as well as walk_system_ram_range().
walk_system_ram_range() must be defined somewhere because it is expected to be generic routine: exported and called from both in-kernel and out-of-tree code.

Yes, powerpc has its own walk_system_ram_range() and page_is_ram() ;-)

Would it be better if moving the weak attribute page_is_ram() into #if !defined(CONFIG_ARCH_HAS_WALK_MEMORY) ?

Quoted 3 lines

Thanks,
Fengguang

Wu Fengguang

author

2010-01-22 05:52 UTC #7 lore raw

Re: [PATCH 1/3] resources: introduce generic page_is_ram()

Quoted 62 lines · Xiaotian Feng

Quoted 52 lines · Wu Fengguang
Quoted 27 lines · Xiaotian Feng
Quoted 26 lines · Wu Fengguang
It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().
The static verions in MIPS and SCORE are also made global.
CC Chen Liqin <[email protected]>
CC Lennox Wu <[email protected]>
CC Ralf Baechle <[email protected]>
CC Américo Wang <[email protected]>
CC [email protected]
CC KAMEZAWA Hiroyuki <[email protected]>
CC Yinghai Lu <[email protected]>
Signed-off-by Wu Fengguang <[email protected]>
---
arch/mips/mm/init.c | 2 +-
arch/score/mm/init.c | 2 +-
include/linux/ioport.h | 2 ++
kernel/resource.c | 11 +++++++++++
 4 files changed, 15 insertions(+), 2 deletions(-)
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +0 -0
@@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long
 
  #endif
 
Quoted 13 lines
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 int walk_system_ram_range(unsigned long · line 340
Quoted 11 lines
kernel/resource.c 2010-01-22 11:20:35.000000000 +0800 renamed from kernel/resource.c 2010-01-22 11:20:34.000000000 +0800 +11 -0
+#define PAGE_IS_RAM    24
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+       return PAGE_IS_RAM;
+}
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+       return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+
I'm not sure, but any build test for powerpc/mips/score?
Sorry, no build tests yet:
/bin/sh: score-linux-gcc: command not found
I just make the mips/score page_is_ram() non-static and assume that will make it compile.
Quoted 2 lines
walk_system_ram_range is defined when CONFIG_ARCH_HAS_WALK_MEMORY is not set. Is it safe when CONFIG_ARCH_HAS_WALK_MEMORY is set for some powerpc archs?
Quoted 8 lines
Good question. Grep shows that CONFIG_ARCH_HAS_WALK_MEMORY is only defined for powerpc, and it has its own page_is_ram() as well as walk_system_ram_range().
walk_system_ram_range() must be defined somewhere because it is expected to be generic routine: exported and called from both in-kernel and out-of-tree code.

Quoted 4 lines

Yes, powerpc has its own walk_system_ram_range() and page_is_ram() ;-)
Would it be better if moving the weak attribute page_is_ram() into #if !defined(CONFIG_ARCH_HAS_WALK_MEMORY) ?

Only several archs defined page_is_ram(), so that would not be feasible for doing a _generic_ page_is_ram().

Thanks,
Fengguang

H. Peter Anvin

reviewer

2010-01-22 07:53 UTC #8 lore raw

Re: [PATCH 1/3] resources: introduce generic page_is_ram()

Quoted 7 lines · Wu Fengguang

kernel/resource.c +1 -0

@@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long 
 
 #endif
 
+#define PAGE_IS_RAM	24

kernel/resource.c int walk_system_ram_range(unsigned long · line 340

Quoted 10 lines

kernel/resource.c +10 -0

+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+	return PAGE_IS_RAM;
+}
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+	return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+

Stylistic nitpick:

The use of the magic number "24" here is pretty ugly; it seems to imply that there is something peculiar with this number and that it is trying to avoid an overlap, whereas in fact any number but 0 and -1 would do.

I would rather see just returning 1 and do:

	return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;

(walk_system_ram_range() returning -1 on error, and 0 means continue.)

Note also that we don't write "constant == expression"; although some schools teach it as a way to avoid the "=" versus "==" beginner C mistake, it makes the code less intuitive to read.

Other than that, the patchset looks good; if Ingo doesn't beat me to it I'll put it in tomorrow (need sleep right now.)

-hpa

Signature · 2 lines

H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

Wu Fengguang

author

2010-01-22 08:16 UTC #9 lore raw

PATCH v4 1/3 resources: introduce generic page_is_ram()

Quoted 21 lines · H. Peter Anvin

Quoted 7 lines · Wu Fengguang

kernel/resource.c +1 -0

@@ -327,6 +327,17 @@ int walk_system_ram_range(unsigned long 
 
 #endif
 
+#define PAGE_IS_RAM	24

kernel/resource.c int walk_system_ram_range(unsigned long · line 340

Quoted 10 lines

kernel/resource.c +10 -0

+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+	return PAGE_IS_RAM;
+}
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+	return PAGE_IS_RAM == walk_system_ram_range(pfn, 1, NULL, __is_ram);
+}
+#undef PAGE_IS_RAM
+

Stylistic nitpick:

Quoted 3 lines

The use of the magic number "24" here is pretty ugly; it seems to imply that there is something peculiar with this number and that it is trying to avoid an overlap, whereas in fact any number but 0 and -1 would do.

Yes, exactly.

Quoted 5 lines

I would rather see just returning 1 and do:
	return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
(walk_system_ram_range() returning -1 on error, and 0 means continue.)

Good suggestion.

Quoted 3 lines

Note also that we don't write "constant == expression"; although some schools teach it as a way to avoid the "=" versus "==" beginner C mistake, it makes the code less intuitive to read.

Yeah.

Quoted 2 lines

Other than that, the patchset looks good; if Ingo doesn't beat me to it I'll put it in tomorrow (need sleep right now.)

OK, thanks! Here is the updated patch.

---
resources: introduce generic page_is_ram()

It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().

The static verions in MIPS and SCORE are also made global.

v4: prefer plain 1 instead of PAGE_IS_RAM (H. Peter Anvin)
v3: add comment (KAMEZAWA Hiroyuki)
"AFAIK, this "System RAM" information has been used for kdump to grab valid memory area and seems good for the kernel itself."
v2: add PAGE_IS_RAM macro (Américo Wang)

CC Chen Liqin <[email protected]>

CC Lennox Wu <[email protected]>

CC Ralf Baechle <[email protected]>

CC Américo Wang <[email protected]>

CC [email protected]

CC Yinghai Lu <[email protected]>

---
 arch/mips/mm/init.c    |    2 +-
 arch/score/mm/init.c   |    2 +-
 include/linux/ioport.h |    2 ++
 kernel/resource.c      |   13 +++++++++++++
 4 files changed, 17 insertions(+), 2 deletions(-)

kernel/resource.c +13 -0

@@ -327,6 +327,19 @@ int walk_system_ram_range(unsigned long 
 
 #endif
 
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+	return 1;
+}
+/*
+ * This generic page_is_ram() returns true if specified address is
+ * registered as "System RAM" in iomem_resource list.
+ */
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+	return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
+}
+
 /*
  * Find empty slot in the resource tree given range and alignment.
  */

include/linux/ioport.h +2 -0

@@ -191,5 +191,7 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 
+extern int page_is_ram(unsigned long pfn);
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */

arch/score/mm/init.c +1 -1

@@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
 		return 1;

arch/mips/mm/init.c +1 -1

@@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long 
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	int i;

Andrew Morton

maintainer

2010-01-27 00:32 UTC #10 lore raw

Re: [PATCH 1/3 v4] resources: introduce generic page_is_ram()

Quoted 35 lines · On Fri, 22 Jan 2010 16:16:19 +0800 Wu Fengguang <[email protected]> wrote:

It's based on walk_system_ram_range(), for archs that don't have their own page_is_ram().
The static verions in MIPS and SCORE are also made global.
v4: prefer plain 1 instead of PAGE_IS_RAM (H. Peter Anvin)
v3: add comment (KAMEZAWA Hiroyuki)
"AFAIK, this "System RAM" information has been used for kdump to grab valid memory area and seems good for the kernel itself."
v2: add PAGE_IS_RAM macro (Am__rico Wang)
CC Chen Liqin <[email protected]>
CC Lennox Wu <[email protected]>
CC Ralf Baechle <[email protected]>
CC Am__rico Wang <[email protected]>
CC [email protected]
CC Yinghai Lu <[email protected]>
Reviewed-by KAMEZAWA Hiroyuki <[email protected]>
Signed-off-by Wu Fengguang <[email protected]>
---
 arch/mips/mm/init.c    |    2 +-
 arch/score/mm/init.c   |    2 +-
 include/linux/ioport.h |    2 ++
 kernel/resource.c      |   13 +++++++++++++
 4 files changed, 17 insertions(+), 2 deletions(-)
kernel/resource.c +2 -0
@@ -327,6 +327,19 @@ int walk_system_ram_range(unsigned long 
 
 #endif
 
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{

kernel/resource.c int walk_system_ram_range(unsigned long · line 341

Quoted 10 lines

kernel/resource.c +10 -0

+	return 1;
+}
+/*
+ * This generic page_is_ram() returns true if specified address is
+ * registered as "System RAM" in iomem_resource list.
+ */
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+	return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
+}

I'll switch this to use __weak.

include/linux/ioport.h extern int · line 194

Quoted 10 lines

kernel/resource.c +0 -0

 /*
  * Find empty slot in the resource tree given range and alignment.
  */

include/linux/ioport.h +1 -0

@@ -191,5 +191,7 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 
+extern int page_is_ram(unsigned long pfn);

Is it appropriate that this function be declared in ioport.h? It's a pretty general function. Dunno.

Quoted 16 lines

include/linux/ioport.h +0 -0

 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */

arch/score/mm/init.c +1 -1

@@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
 		return 1;

arch/mips/mm/init.c void __init fixrange_init(unsigned long · line 303

Quoted 7 lines

arch/mips/mm/init.c +1 -1

@@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long 
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	int i;

hm, so we lose the __init.

Wu Fengguang

author

2010-01-27 03:07 UTC #11 lore raw

Re: [PATCH 1/3 v4] resources: introduce generic page_is_ram()

Quoted 6 lines · Andrew Morton

Review
Quoted 4 lines
(quoted diff) +4 -0
+int __attribute__((weak)) page_is_ram(unsigned long pfn)
+{
+	return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
+}
I'll switch this to use __weak.

Thanks.

Quoted 9 lines

Quoted 9 lines
/*
* Find empty slot in the resource tree given range and alignment. */
include/linux/ioport.h +0 -0
@@ -191,5 +191,7 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 

Quoted 4 lines

include/linux/ioport.h extern int · line 194
Quoted 1 line
include/linux/ioport.h +1 -0
+extern int page_is_ram(unsigned long pfn);
Is it appropriate that this function be declared in ioport.h? It's a pretty general function. Dunno.

Good suggestion. The following patch moves it to mm.h.

Quoted 18 lines

include/linux/ioport.h +0 -0

 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */

arch/score/mm/init.c +1 -1

@@ -59,7 +59,7 @@ static unsigned long setup_zero_page(voi
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	if (pagenr >= min_low_pfn && pagenr < max_low_pfn)
 		return 1;

arch/mips/mm/init.c +0 -0

@@ -298,7 +298,7 @@ void __init fixrange_init(unsigned long 
 }

Quoted 7 lines

arch/mips/mm/init.c void __init fixrange_init(unsigned long · line 303
Quoted 5 lines
arch/mips/mm/init.c +1 -1
 #ifndef CONFIG_NEED_MULTIPLE_NODES
-static int __init page_is_ram(unsigned long pagenr)
+int page_is_ram(unsigned long pagenr)
 {
 	int i;
hm, so we lose the __init.

Maybe Ralf Baechle knows whether MIPS can switch to the (smaller) generic page_is_ram().

Thanks,
Fengguang
---
move page_is_ram() declaration to mm.h

---
 include/linux/ioport.h |    2 --
 include/linux/mm.h     |    2 ++
 2 files changed, 2 insertions(+), 2 deletions(-)

include/linux/ioport.h +0 -2

@@ -191,7 +191,5 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 
-extern int page_is_ram(unsigned long pfn);
-
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */

include/linux/mm.h +2 -0

@@ -265,6 +265,8 @@ static inline int get_page_unless_zero(s
 	return atomic_inc_not_zero(&page->_count);
 }
 
+extern int page_is_ram(unsigned long pfn);
+
 /* Support for virtually mapped pages */
 struct page *vmalloc_to_page(const void *addr);
 unsigned long vmalloc_to_pfn(const void *addr);

tip-bot for Wu Fengguang

author

2010-02-02 01:01 UTC #12 lore raw

[tip:x86/mm] Move page_is_ram() declaration to mm.h

Commit-ID:  53df8fdc15fb646b0219e43c989c2cdab1ab100c
Gitweb:     http://git.kernel.org/tip/53df8fdc15fb646b0219e43c989c2cdab1ab100c
Author:     Wu Fengguang <[email protected]>
AuthorDate: Wed, 27 Jan 2010 11:06:39 +0800
Committer:  H. Peter Anvin <[email protected]>
CommitDate: Mon, 1 Feb 2010 16:58:17 -0800

Move page_is_ram() declaration to mm.h

Move page_is_ram() declaration to mm.h, it makes no sense in <linux/ioport.h>.

LKML-Reference: <20100127030639.GD8132@localhost>

Signed-off-by H. Peter Anvin <[email protected]>

---
 include/linux/ioport.h |    2 --
 include/linux/mm.h     |    2 ++
 2 files changed, 2 insertions(+), 2 deletions(-)

include/linux/ioport.h +0 -2

index 11ef795..83aa812 100644
@@ -188,7 +188,5 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));
 
-extern int page_is_ram(unsigned long pfn);
-
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */

include/linux/mm.h +2 -0

index 24c3956..bad433f 100644
@@ -265,6 +265,8 @@ static inline int get_page_unless_zero(struct page *page)
 	return atomic_inc_not_zero(&page->_count);
 }
 
+extern int page_is_ram(unsigned long pfn);
+
 /* Support for virtually mapped pages */
 struct page *vmalloc_to_page(const void *addr);
 unsigned long vmalloc_to_pfn(const void *addr);

Wu Fengguang

author

2010-01-22 03:30 UTC #13 lore raw

PATCH 2/3 x86: remove bios data range from e820

From: Yinghai Lu <[email protected]>

To prepare move page_is_ram() as generic one.

Tested-by Wu Fengguang <[email protected]>

Signed-off-by Yinghai Lu <[email protected]>

---
 arch/x86/kernel/e820.c  |    8 ++++++++
 arch/x86/kernel/setup.c |   19 ++++++++++++++++++-
 arch/x86/mm/ioremap.c   |   16 ----------------
 3 files changed, 26 insertions(+), 17 deletions(-)

arch/x86/kernel/setup.c +18 -1

@@ -659,6 +659,23 @@ static struct dmi_system_id __initdata b
 	{}
 };
 
+static void __init trim_bios_range(void)
+{
+	/*
+	 * A special case is the first 4Kb of memory;
+	 * This is a BIOS owned area, not kernel ram, but generally
+	 * not listed as such in the E820 table.
+	 */
+	e820_update_range(0, PAGE_SIZE, E820_RAM, E820_RESERVED);
+	/*
+	 * special case: Some BIOSen report the PC BIOS
+	 * area (640->1Mb) as ram even though it is not.
+	 * take them out.
+	 */
+	e820_remove_range(BIOS_BEGIN, BIOS_END - BIOS_BEGIN, E820_RAM, 1);
+	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
+}
+
 /*
  * Determine if we were loaded by an EFI loader.  If so, then we have also been
  * passed the efi memmap, systab, etc., so we should use these data structures

@@ -822,7 +839,7 @@ void __init setup_arch(char **cmdline_p)
 	insert_resource(&iomem_resource, &data_resource);
 	insert_resource(&iomem_resource, &bss_resource);
 
-
+	trim_bios_range();
 #ifdef CONFIG_X86_32
 	if (ppro_with_ram_bug()) {
 		e820_update_range(0x70000000ULL, 0x40000ULL, E820_RAM,

arch/x86/kernel/e820.c +8 -0

@@ -517,11 +517,19 @@ u64 __init e820_remove_range(u64 start, 
 			     int checktype)
 {
 	int i;
+	u64 end;
 	u64 real_removed_size = 0;
 
 	if (size > (ULLONG_MAX - start))
 		size = ULLONG_MAX - start;
 
+	end = start + size;
+	printk(KERN_DEBUG "e820 remove range: %016Lx - %016Lx ",
+		       (unsigned long long) start,
+		       (unsigned long long) end);
+	e820_print_type(old_type);
+	printk(KERN_CONT "\n");
+
 	for (i = 0; i < e820.nr_map; i++) {
 		struct e820entry *ei = &e820.map[i];
 		u64 final_start, final_end;

arch/x86/mm/ioremap.c +0 ~~-16~~

@@ -29,22 +29,6 @@ int page_is_ram(unsigned long pagenr)
 	resource_size_t addr, end;
 	int i;
 
-	/*
-	 * A special case is the first 4Kb of memory;
-	 * This is a BIOS owned area, not kernel ram, but generally
-	 * not listed as such in the E820 table.
-	 */
-	if (pagenr == 0)
-		return 0;
-
-	/*
-	 * Second special case: Some BIOSen report the PC BIOS
-	 * area (640->1Mb) as ram even though it is not.
-	 */
-	if (pagenr >= (BIOS_BEGIN >> PAGE_SHIFT) &&
-		    pagenr < (BIOS_END >> PAGE_SHIFT))
-		return 0;
-
 	for (i = 0; i < e820.nr_map; i++) {
 		/*
 		 * Not usable memory:

Wu Fengguang

author

2010-01-22 04:06 UTC #14 lore raw

Re: [PATCH 2/3] x86: remove bios data range from e820

Quoted 3 lines · Fengguang

From: Yinghai Lu <[email protected]>
To prepare move page_is_ram() as generic one.

Yinghai,

The following two chunks cannot apply because the lines they remove don't exist in linux-next. Because this patchset is targeted for 2.6.34, I just remove the chunks.

===================================================================

arch/x86/kernel/head32.c +0 -2

@@ -29,8 +29,6 @@ static void __init i386_default_early_se
 
 void __init i386_start_kernel(void)
 {
-       reserve_early_overlap_ok(0, PAGE_SIZE, "BIOS data page");
-
 #ifdef CONFIG_X86_TRAMPOLINE
        /*
         * But first pinch a few for the stack/trampoline stuff

arch/x86/kernel/head64.c +0 -2

Index: linux-2.6/arch/x86/kernel/head64.c
===================================================================
@@ -98,8 +98,6 @@ void __init x86_64_start_reservations(ch
 {
        copy_bootdata(__va(real_mode_data));
 
-       reserve_early_overlap_ok(0, PAGE_SIZE, "BIOS data page");
-
        reserve_early(__pa_symbol(&_text), __pa_symbol(&__bss_stop), "TEXT DATA BSS");
 
 #ifdef CONFIG_BLK_DEV_INITRD

Thanks,
Fengguang

Andrew Morton

maintainer

2010-01-27 00:34 UTC #15 lore raw

Re: [PATCH 2/3] x86: remove bios data range from e820

Quoted 6 lines · On Fri, 22 Jan 2010 11:21:04 +0800 Wu Fengguang <[email protected]> wrote:

From: Yinghai Lu <[email protected]>
To prepare move page_is_ram() as generic one.
Tested-by Wu Fengguang <[email protected]>
Signed-off-by Yinghai Lu <[email protected]>

This should have included Signed-off-by:you, as you were on the patch delivery path. I shall add that.

tip-bot for Yinghai Lu

2010-02-02 01:01 UTC #16 lore raw

[tip:x86/mm] x86: Remove BIOS data range from e820

Commit-ID:  1b5576e69a5fe168c08a159685ac366316ac9bbc
Gitweb:     http://git.kernel.org/tip/1b5576e69a5fe168c08a159685ac366316ac9bbc
Author:     Yinghai Lu <[email protected]>
AuthorDate: Fri, 22 Jan 2010 11:21:04 +0800
Committer:  H. Peter Anvin <[email protected]>
CommitDate: Mon, 1 Feb 2010 16:58:17 -0800

x86: Remove BIOS data range from e820

In preparation for moving to the generic page_is_ram(), make explicit what we expect to be reserved and not reserved.

Tested-by Wu Fengguang <[email protected]>

Signed-off-by Yinghai Lu <[email protected]>

LKML-Reference: <[email protected]>

Cc Andrew Morton <[email protected]>

Signed-off-by H. Peter Anvin <[email protected]>

---
 arch/x86/kernel/e820.c  |    8 ++++++++
 arch/x86/kernel/setup.c |   19 ++++++++++++++++++-
 arch/x86/mm/ioremap.c   |   16 ----------------
 3 files changed, 26 insertions(+), 17 deletions(-)

arch/x86/kernel/e820.c +8 -0

index d17d482..230687b 100644
@@ -517,11 +517,19 @@ u64 __init e820_remove_range(u64 start, u64 size, unsigned old_type,
 			     int checktype)
 {
 	int i;
+	u64 end;
 	u64 real_removed_size = 0;
 
 	if (size > (ULLONG_MAX - start))
 		size = ULLONG_MAX - start;
 
+	end = start + size;
+	printk(KERN_DEBUG "e820 remove range: %016Lx - %016Lx ",
+		       (unsigned long long) start,
+		       (unsigned long long) end);
+	e820_print_type(old_type);
+	printk(KERN_CONT "\n");
+
 	for (i = 0; i < e820.nr_map; i++) {
 		struct e820entry *ei = &e820.map[i];
 		u64 final_start, final_end;

arch/x86/kernel/setup.c +18 -1

index cdb6a8a..f9b1f4e 100644
@@ -650,6 +650,23 @@ static struct dmi_system_id __initdata bad_bios_dmi_table[] = {
 	{}
 };
 
+static void __init trim_bios_range(void)
+{
+	/*
+	 * A special case is the first 4Kb of memory;
+	 * This is a BIOS owned area, not kernel ram, but generally
+	 * not listed as such in the E820 table.
+	 */
+	e820_update_range(0, PAGE_SIZE, E820_RAM, E820_RESERVED);
+	/*
+	 * special case: Some BIOSen report the PC BIOS
+	 * area (640->1Mb) as ram even though it is not.
+	 * take them out.
+	 */
+	e820_remove_range(BIOS_BEGIN, BIOS_END - BIOS_BEGIN, E820_RAM, 1);
+	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
+}
+
 /*
  * Determine if we were loaded by an EFI loader.  If so, then we have also been
  * passed the efi memmap, systab, etc., so we should use these data structures

@@ -813,7 +830,7 @@ void __init setup_arch(char **cmdline_p)
 	insert_resource(&iomem_resource, &data_resource);
 	insert_resource(&iomem_resource, &bss_resource);
 
-
+	trim_bios_range();
 #ifdef CONFIG_X86_32
 	if (ppro_with_ram_bug()) {
 		e820_update_range(0x70000000ULL, 0x40000ULL, E820_RAM,

arch/x86/mm/ioremap.c +0 ~~-16~~

index 334e63c..30e068d 100644
@@ -29,22 +29,6 @@ int page_is_ram(unsigned long pagenr)
 	resource_size_t addr, end;
 	int i;
 
-	/*
-	 * A special case is the first 4Kb of memory;
-	 * This is a BIOS owned area, not kernel ram, but generally
-	 * not listed as such in the E820 table.
-	 */
-	if (pagenr == 0)
-		return 0;
-
-	/*
-	 * Second special case: Some BIOSen report the PC BIOS
-	 * area (640->1Mb) as ram even though it is not.
-	 */
-	if (pagenr >= (BIOS_BEGIN >> PAGE_SHIFT) &&
-		    pagenr < (BIOS_END >> PAGE_SHIFT))
-		return 0;
-
 	for (i = 0; i < e820.nr_map; i++) {
 		/*
 		 * Not usable memory:

Wu Fengguang

author

2010-01-22 03:31 UTC #17 lore raw

PATCH 3/3 x86: use the generic page_is_ram()

The generic resource based page_is_ram() works better with memory hotplug/hotremove. So switch the x86 e820map based code to it.

CC Andi Kleen <[email protected]>

CC KAMEZAWA Hiroyuki <[email protected]>

CC Yinghai Lu <[email protected]>

---
 arch/x86/include/asm/page_types.h |    1 -
 arch/x86/mm/ioremap.c             |   21 ---------------------
 2 files changed, 22 deletions(-)

arch/x86/include/asm/page_types.h +0 -1

@@ -40,7 +40,6 @@
 
 #ifndef __ASSEMBLY__
 
-extern int page_is_ram(unsigned long pagenr);
 extern int devmem_is_allowed(unsigned long pagenr);
 
 extern unsigned long max_low_pfn_mapped;

arch/x86/mm/ioremap.c +0 ~~-21~~

@@ -24,27 +24,6 @@
 
 #include "physaddr.h"
 
-int page_is_ram(unsigned long pagenr)
-{
-	resource_size_t addr, end;
-	int i;
-
-	for (i = 0; i < e820.nr_map; i++) {
-		/*
-		 * Not usable memory:
-		 */
-		if (e820.map[i].type != E820_RAM)
-			continue;
-		addr = (e820.map[i].addr + PAGE_SIZE-1) >> PAGE_SHIFT;
-		end = (e820.map[i].addr + e820.map[i].size) >> PAGE_SHIFT;
-
-
-		if ((pagenr >= addr) && (pagenr < end))
-			return 1;
-	}
-	return 0;
-}
-
 /*
  * Fix up the linear direct mapping of the kernel to avoid cache attribute
  * conflicts.

tip-bot for Wu Fengguang

author

2010-02-02 01:02 UTC #18 lore raw

[tip:x86/mm] x86: Use the generic page_is_ram()

Commit-ID:  13ca0fcaa33f6b1984c4111b6ec5df42689fea6f
Gitweb:     http://git.kernel.org/tip/13ca0fcaa33f6b1984c4111b6ec5df42689fea6f
Author:     Wu Fengguang <[email protected]>
AuthorDate: Fri, 22 Jan 2010 11:21:05 +0800
Committer:  H. Peter Anvin <[email protected]>
CommitDate: Mon, 1 Feb 2010 16:58:17 -0800

x86: Use the generic page_is_ram()

The generic resource based page_is_ram() works better with memory hotplug/hotremove. So switch the x86 e820map based code to it.

CC Andi Kleen <[email protected]>

CC KAMEZAWA Hiroyuki <[email protected]>

CC Yinghai Lu <[email protected]>