Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[Dave Hansen]

On Mon, 2011-05-02 at 23:19 +0200, Daniel Kiper wrote:
> Memory hotplug code strictly depends on CONFIG_SPARSEMEM.
> It means that code depending on CONFIG_FLATMEM in online_page()
> is never compiled. Remove it because it is not needed anymore.

It's subtle, but I don't think that's true.  We had another hotplug mode
for x86_64 before folks were comfortable turning SPARSEMEM on for the
whole architecture.  It was quite possible to have memory hotplug
without sparsemem in that case.  I think Keith Mannthey did some of that
code if I remember right.

But, I'm not sure how much of that stayed in distros versus made it
upstream.  In any case, you might want to chase down the
X86_64_ACPI_NUMA bit to make sure it can't be used with FLATMEM ever.

config MEMORY_HOTPLUG
        bool "Allow for memory hot-add"
        depends on SPARSEMEM || X86_64_ACPI_NUMA
        depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
        depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)

-- Dave

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Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[Daniel Kiper]

On Mon, May 02, 2011 at 02:25:04PM -0700, Dave Hansen wrote:
> On Mon, 2011-05-02 at 23:19 +0200, Daniel Kiper wrote:
> > Memory hotplug code strictly depends on CONFIG_SPARSEMEM.
> > It means that code depending on CONFIG_FLATMEM in online_page()
> > is never compiled. Remove it because it is not needed anymore.
>
> It's subtle, but I don't think that's true.  We had another hotplug mode
> for x86_64 before folks were comfortable turning SPARSEMEM on for the
> whole architecture.  It was quite possible to have memory hotplug
> without sparsemem in that case.  I think Keith Mannthey did some of that
> code if I remember right.
>
> But, I'm not sure how much of that stayed in distros versus made it
> upstream.  In any case, you might want to chase down the
> X86_64_ACPI_NUMA bit to make sure it can't be used with FLATMEM ever.
>
> config MEMORY_HOTPLUG
>         bool "Allow for memory hot-add"
>         depends on SPARSEMEM || X86_64_ACPI_NUMA
>         depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
>         depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)

IIRC some time ago it was possible to enable memory hotplug with
CONFIG_FLATMEM. That is why I looked for any dependencies of memory
hoplug code on CONFIG_FLATMEM in current Linux Kernel source. I could
not find anything and that is why I published this patch. However,
maybe I missed something.

Daniel

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Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[Dave Hansen]

On Tue, 2011-05-03 at 00:18 +0200, Daniel Kiper wrote:
> 
> > config MEMORY_HOTPLUG
> >         bool "Allow for memory hot-add"
> >         depends on SPARSEMEM || X86_64_ACPI_NUMA
> >         depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
> >         depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
> 
> IIRC some time ago it was possible to enable memory hotplug with
> CONFIG_FLATMEM. That is why I looked for any dependencies of memory
> hoplug code on CONFIG_FLATMEM in current Linux Kernel source. I could
> not find anything and that is why I published this patch. However,
> maybe I missed something.

I can't find any immediately apparent case, either.  Guess that's what
LKML is for. :)

Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>

-- Dave

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Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[David Rientjes]

On Mon, 2 May 2011, Daniel Kiper wrote:

> Memory hotplug code strictly depends on CONFIG_SPARSEMEM.
> It means that code depending on CONFIG_FLATMEM in online_page()
> is never compiled. Remove it because it is not needed anymore.
> 
> Signed-off-by: Daniel Kiper <dkiper@net-space.pl>

The code you're patching depends on CONFIG_MEMORY_HOTPLUG_SPARSE, so this 
is valid.  The changelog should be updated to reflect that, however.

Acked-by: David Rientjes <rientjes@google.com>

Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[Daniel Kiper]

On Wed, May 11, 2011 at 03:47:49PM -0700, David Rientjes wrote:
> On Mon, 2 May 2011, Daniel Kiper wrote:
>
> > Memory hotplug code strictly depends on CONFIG_SPARSEMEM.
> > It means that code depending on CONFIG_FLATMEM in online_page()
> > is never compiled. Remove it because it is not needed anymore.
> >
> > Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
>
> The code you're patching depends on CONFIG_MEMORY_HOTPLUG_SPARSE, so this
> is valid.  The changelog should be updated to reflect that, however.
>
> Acked-by: David Rientjes <rientjes@google.com>

No problem, however, this bundle of patches was added to the -mm tree.
In this situation should I repost whole bundle with relevant changes
or post only those two patches requested by you ??? For which tree
should I prepare new version of patches ???

Daniel

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Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[David Rientjes]

On Thu, 12 May 2011, Daniel Kiper wrote:

> > > Memory hotplug code strictly depends on CONFIG_SPARSEMEM.
> > > It means that code depending on CONFIG_FLATMEM in online_page()
> > > is never compiled. Remove it because it is not needed anymore.
> > >
> > > Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
> >
> > The code you're patching depends on CONFIG_MEMORY_HOTPLUG_SPARSE, so this
> > is valid.  The changelog should be updated to reflect that, however.
> >
> > Acked-by: David Rientjes <rientjes@google.com>
> 
> No problem, however, this bundle of patches was added to the -mm tree.
> In this situation should I repost whole bundle with relevant changes
> or post only those two patches requested by you ??? For which tree
> should I prepare new version of patches ???
> 

No, I would just reply to the email notification you received when the 
patch went into -mm saying that the changelog should be adjusted to read 
something like

	online_pages() is only compiled for CONFIG_MEMORY_HOTPLUG_SPARSE,
	so there is no need to support CONFIG_FLATMEM code within it.

	This patch removes code that is never used.

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Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[Daniel Kiper]

[-- Attachment #1: Type: text/plain, Size: 1320 bytes --]

On Thu, May 12, 2011 at 12:26:22PM -0700, David Rientjes wrote:
> On Thu, 12 May 2011, Daniel Kiper wrote:
>
> > > > Memory hotplug code strictly depends on CONFIG_SPARSEMEM.
> > > > It means that code depending on CONFIG_FLATMEM in online_page()
> > > > is never compiled. Remove it because it is not needed anymore.
> > > >
> > > > Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
> > >
> > > The code you're patching depends on CONFIG_MEMORY_HOTPLUG_SPARSE, so this
> > > is valid.  The changelog should be updated to reflect that, however.
> > >
> > > Acked-by: David Rientjes <rientjes@google.com>
> >
> > No problem, however, this bundle of patches was added to the -mm tree.
> > In this situation should I repost whole bundle with relevant changes
> > or post only those two patches requested by you ??? For which tree
> > should I prepare new version of patches ???
> >
>
> No, I would just reply to the email notification you received when the
> patch went into -mm saying that the changelog should be adjusted to read
> something like
>
> 	online_pages() is only compiled for CONFIG_MEMORY_HOTPLUG_SPARSE,
> 	so there is no need to support CONFIG_FLATMEM code within it.
>
> 	This patch removes code that is never used.

Please look into attachments.

If you have any questions please drop me a line.

Daniel

[-- Attachment #2: mm-enable-set_page_section-only-if-config_sparsemem-and-config_sparsemem_vmemmap.patch --]
[-- Type: text/plain, Size: 5056 bytes --]

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Subject: + mm-enable-set_page_section-only-if-config_sparsemem-and-config_sparsemem_vmemmap.patch added to -mm tree
To:	mm-commits@vger.kernel.org
Cc:	dkiper@net-space.pl, dave@linux.vnet.ibm.com
From:	akpm@linux-foundation.org
Date:	Tue, 03 May 2011 16:35:54 -0700
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The patch titled
     mm: enable set_page_section() only if CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP
has been added to the -mm tree.  Its filename is
     mm-enable-set_page_section-only-if-config_sparsemem-and-config_sparsemem_vmemmap.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: mm: enable set_page_section() only if CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP
From: Daniel Kiper <dkiper@net-space.pl>

set_page_section() is valid only in CONFIG_SPARSEMEM and
!CONFIG_SPARSEMEM_VMEMMAP context.  Move it to proper place and amend
accordingly functions which are using it.

Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff -puN include/linux/mm.h~mm-enable-set_page_section-only-if-config_sparsemem-and-config_sparsemem_vmemmap include/linux/mm.h
--- a/include/linux/mm.h~mm-enable-set_page_section-only-if-config_sparsemem-and-config_sparsemem_vmemmap
+++ a/include/linux/mm.h
@@ -682,6 +682,12 @@ static inline struct zone *page_zone(str
 }
 
 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
+static inline void set_page_section(struct page *page, unsigned long section)
+{
+	page->flags &= ~(SECTIONS_MASK << SECTIONS_PGSHIFT);
+	page->flags |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
+}
+
 static inline unsigned long page_to_section(struct page *page)
 {
 	return (page->flags >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
@@ -700,18 +706,14 @@ static inline void set_page_node(struct 
 	page->flags |= (node & NODES_MASK) << NODES_PGSHIFT;
 }
 
-static inline void set_page_section(struct page *page, unsigned long section)
-{
-	page->flags &= ~(SECTIONS_MASK << SECTIONS_PGSHIFT);
-	page->flags |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
-}
-
 static inline void set_page_links(struct page *page, enum zone_type zone,
 	unsigned long node, unsigned long pfn)
 {
 	set_page_zone(page, zone);
 	set_page_node(page, node);
+#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 	set_page_section(page, pfn_to_section_nr(pfn));
+#endif
 }
 
 /*
_

Patches currently in -mm which might be from dkiper@net-space.pl are

linux-next.patch
mm-remove-dependency-on-config_flatmem-from-online_page.patch
mm-enable-set_page_section-only-if-config_sparsemem-and-config_sparsemem_vmemmap.patch
mm-pfn_to_section_nr-section_nr_to_pfn-is-valid-only-in-config_sparsemem-context.patch
mm-do-not-define-pfn_section_shift-if-config_sparsemem.patch



[-- Attachment #3: mm-remove-dependency-on-config_flatmem-from-online_page.patch --]
[-- Type: text/plain, Size: 4019 bytes --]

>From akpm@linux-foundation.org Wed May  4 01:36:13 2011
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Subject: + mm-remove-dependency-on-config_flatmem-from-online_page.patch added to -mm tree
To:	mm-commits@vger.kernel.org
Cc:	dkiper@net-space.pl, dave@linux.vnet.ibm.com
From:	akpm@linux-foundation.org
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The patch titled
     mm: remove dependency on CONFIG_FLATMEM from online_page()
has been added to the -mm tree.  Its filename is
     mm-remove-dependency-on-config_flatmem-from-online_page.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: mm: remove dependency on CONFIG_FLATMEM from online_page()
From: Daniel Kiper <dkiper@net-space.pl>

Memory hotplug code strictly depends on CONFIG_SPARSEMEM.  It means that
code depending on CONFIG_FLATMEM in online_page() is never compiled. 
Remove it because it is not needed anymore.

Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory_hotplug.c |    4 ----
 1 file changed, 4 deletions(-)

diff -puN mm/memory_hotplug.c~mm-remove-dependency-on-config_flatmem-from-online_page mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~mm-remove-dependency-on-config_flatmem-from-online_page
+++ a/mm/memory_hotplug.c
@@ -374,10 +374,6 @@ void online_page(struct page *page)
 		totalhigh_pages++;
 #endif
 
-#ifdef CONFIG_FLATMEM
-	max_mapnr = max(pfn, max_mapnr);
-#endif
-
 	ClearPageReserved(page);
 	init_page_count(page);
 	__free_page(page);
_

Patches currently in -mm which might be from dkiper@net-space.pl are

linux-next.patch
mm-remove-dependency-on-config_flatmem-from-online_page.patch
mm-enable-set_page_section-only-if-config_sparsemem-and-config_sparsemem_vmemmap.patch
mm-pfn_to_section_nr-section_nr_to_pfn-is-valid-only-in-config_sparsemem-context.patch
mm-do-not-define-pfn_section_shift-if-config_sparsemem.patch

Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[David Rientjes]

On Mon, 16 May 2011, Daniel Kiper wrote:

> > No, I would just reply to the email notification you received when the
> > patch went into -mm saying that the changelog should be adjusted to read
> > something like
> >
> > 	online_pages() is only compiled for CONFIG_MEMORY_HOTPLUG_SPARSE,
> > 	so there is no need to support CONFIG_FLATMEM code within it.
> >
> > 	This patch removes code that is never used.
> 
> Please look into attachments.
> 
> If you have any questions please drop me a line.
> 

Not sure why you've attached the emails from the mm-commits mailing list.  
I'll respond to the commits with with my suggestions for how the changelog 
should be fixed.

Thanks.

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Re: [PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[Daniel Kiper]

On Mon, May 16, 2011 at 01:32:19PM -0700, David Rientjes wrote:
> On Mon, 16 May 2011, Daniel Kiper wrote:
>
> > > No, I would just reply to the email notification you received when the
> > > patch went into -mm saying that the changelog should be adjusted to read
> > > something like
> > >
> > > 	online_pages() is only compiled for CONFIG_MEMORY_HOTPLUG_SPARSE,
> > > 	so there is no need to support CONFIG_FLATMEM code within it.
> > >
> > > 	This patch removes code that is never used.
> >
> > Please look into attachments.
> >
> > If you have any questions please drop me a line.
>
> Not sure why you've attached the emails from the mm-commits mailing list.

I attached emails from the mm-commits mailing list because
I understood that you need them to correct changelogs.

> I'll respond to the commits with with my suggestions for how the changelog
> should be fixed.

I saw your replies. Thank you for your help.

Daniel

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[PATCH 1/4] mm: Remove dependency on CONFIG_FLATMEM from online_page()

[Daniel Kiper]

Memory hotplug code strictly depends on CONFIG_SPARSEMEM.
It means that code depending on CONFIG_FLATMEM in online_page()
is never compiled. Remove it because it is not needed anymore.

Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
---
 mm/memory_hotplug.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9ca1d60..a807ccb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -374,10 +374,6 @@ void online_page(struct page *page)
 		totalhigh_pages++;
 #endif
 
-#ifdef CONFIG_FLATMEM
-	max_mapnr = max(pfn, max_mapnr);
-#endif
-
 	ClearPageReserved(page);
 	init_page_count(page);
 	__free_page(page);
-- 
1.5.6.5