Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Andrew Morton]

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Thu, 2 Jul 2009 01:22:24 GMT bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=13690
> 
>            Summary: nodes_clear cause hugepage unusable on non-NUMA
>                     machine
>            Product: Platform Specific/Hardware
>            Version: 2.5
>     Kernel Version: 2.6.31-rc1
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: high
>           Priority: P1
>          Component: i386
>         AssignedTo: platform_i386@kernel-bugs.osdl.org
>         ReportedBy: alex.shi@intel.com
>                 CC: yinghai@kernel.org
>         Regression: Yes
> 
> 
> 73d60b7f747176dbdff826c4127d22e1fd3f9f74  commit introduced a nodes_clear
> function for NUMA machine. But seems the commit omits non-NUMA machine.
>  If find_zone_movable_pfns_for_nodes/early_calculate_totalpages has no
>  chance to run. nodes_clear will block HUPEPAGE using in my specjbb2005
>  testing on my Stoakely(i386/x86_64), waybridge(i386), IBM T61(i386)
> 
> +       /*
> +        * find_zone_movable_pfns_for_nodes/early_calculate_totalpages init
> +        * that node_mask, clear it at first
> +        */
> +       nodes_clear(node_states[N_HIGH_MEMORY]);

Thanks.

fyi, with recently-occurring bugs and regressions of this nature, it is (I
think) best to deal with them via email rather than bugzilla.  Bugzilla is
better-suited to longer-lived bugs where we have a need to track them,
generate statistics, etc.

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Yinghai Lu]

that looks strange...

config is 32bit. 

the second patch only do save and restore. and should be right right.

please check following patch on today's linus tree. and send out /proc/iomem

Thanks

Yinghai

[PATCH] x86: add boundary check for 32bit res before expand e820 resource to alignment

fix hang with HIGHMEM_64G and 32bit resource.
according to hpa and Linus, use (resource_size_t)-1 to fend off big ranges.

analyized by hpa

Reported-and-tested-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/include/asm/proto.h |    3 ---
 arch/x86/kernel/e820.c       |   20 ++++++++++++--------
 include/linux/kernel.h       |    5 +++++
 3 files changed, 17 insertions(+), 11 deletions(-)

Index: linux-2.6/arch/x86/kernel/e820.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820.c
+++ linux-2.6/arch/x86/kernel/e820.c
@@ -1367,9 +1367,9 @@ void __init e820_reserve_resources(void)
 }
 
 /* How much should we pad RAM ending depending on where it is? */
-static unsigned long ram_alignment(resource_size_t pos)
+static u64 ram_alignment(u64 pos)
 {
-	unsigned long mb = pos >> 20;
+	u64 mb = pos >> 20;
 
 	/* To 64kB in the first megabyte */
 	if (!mb)
@@ -1383,6 +1383,8 @@ static unsigned long ram_alignment(resou
 	return 32*1024*1024;
 }
 
+#define MAX_RESOURCE_SIZE ((resource_size_t)-1)
+
 void __init e820_reserve_resources_late(void)
 {
 	int i;
@@ -1400,17 +1402,19 @@ void __init e820_reserve_resources_late(
 	 * avoid stolen RAM:
 	 */
 	for (i = 0; i < e820.nr_map; i++) {
-		struct e820entry *entry = &e820_saved.map[i];
-		resource_size_t start, end;
+		struct e820entry *entry = &e820.map[i];
+		u64 start, end;
 
 		if (entry->type != E820_RAM)
 			continue;
 		start = entry->addr + entry->size;
-		end = round_up(start, ram_alignment(start));
-		if (start == end)
+		end = round_up(start, ram_alignment(start)) - 1;
+		if (end > MAX_RESOURCE_SIZE)
+			end = MAX_RESOURCE_SIZE;
+		if (start > end)
 			continue;
-		reserve_region_with_split(&iomem_resource, start,
-						  end - 1, "RAM buffer");
+		reserve_region_with_split(&iomem_resource, start, end,
+					  "RAM buffer");
 	}
 }
 

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Alex Shi]

The new patch works for my stoakley i386 machine. But for x86_64 machine
the specjbb2005 still can not run with hugepage. The specjbb2005 use the
same java setting as i386 system. After apply your patch, the iomem of
x86_64 is:

00000000-0000ffff : reserved
00010000-0009cbff : System RAM
0009cc00-0009ffff : reserved
000cc000-000cffff : reserved
000e0000-000fffff : reserved
00100000-cfefffff : System RAM
  01000000-014eb53e : Kernel code
  014eb53f-0177390f : Kernel data
  01830000-018f583f : Kernel bss
cff00000-cff0afff : ACPI Tables
cff0b000-cff0bfff : ACPI Non-volatile Storage
cff0c000-cfffffff : reserved
d0000000-d7ffffff : PCI Bus 0000:08
  d0000000-d7ffffff : 0000:08:01.0
d8000000-d81fffff : PCI Bus 0000:03
  d8000000-d81fffff : PCI Bus 0000:06
    d8000000-d80fffff : 0000:06:02.0
    d8100000-d810ffff : 0000:06:01.0
d8200000-d84fffff : PCI Bus 0000:03
  d8200000-d83fffff : PCI Bus 0000:06
    d8200000-d82fffff : 0000:06:02.0
      d8200000-d82fffff : e100
    d8300000-d831ffff : 0000:06:01.0
      d8300000-d831ffff : e1000
    d8320000-d832ffff : 0000:06:01.0
      d8320000-d832ffff : e1000
    d8330000-d8330fff : 0000:06:02.0
      d8330000-d8330fff : e100
d8500000-d87fffff : PCI Bus 0000:07
  d8500000-d8503fff : 0000:07:00.0
  d8504000-d8507fff : 0000:07:00.1
  d8520000-d853ffff : 0000:07:00.0
  d8540000-d855ffff : 0000:07:00.1
  d8600000-d86fffff : 0000:07:00.0
  d8700000-d87fffff : 0000:07:00.1
d8800000-d88fffff : PCI Bus 0000:08
  d8800000-d880ffff : 0000:08:01.0
  d8810000-d8813fff : 0000:08:08.0
  d8814000-d88147ff : 0000:08:08.0
  d8820000-d883ffff : 0000:08:01.0
d8904000-d8907fff : 0000:00:1b.0
d8908000-d89083ff : 0000:00:1d.7
  d8908000-d89083ff : ehci_hcd
d8908400-d89087ff : 0000:00:1f.2
  d8908400-d89087ff : ahci
d8a00000-d8bfffff : PCI Bus 0000:07
  d8a00000-d8afffff : 0000:07:00.0
  d8b00000-d8bfffff : 0000:07:00.1
e0000000-efffffff : reserved
  e0000000-efffffff : pnp 00:01
    e0000000-e07fffff : PCI MMCONFIG 0 [00-07]
fe000000-fe01ffff : pnp 00:01
  fe000000-fe01ffff : i5k_amb
fe600000-fe6fffff : pnp 00:01
fe700000-fe703fff : 0000:00:0f.0
fec00000-fec0ffff : reserved
  fec00000-fec00fff : IOAPIC 0
fec88000-fec88fff : IOAPIC 1
  fec88000-fec88fff : pnp 00:01
fec89000-fec89fff : IOAPIC 2
  fec89000-fec89fff : pnp 00:01
fed00000-fed003ff : HPET 0
fed1c000-fed1ffff : pnp 00:01
fed20000-fed44fff : pnp 00:01
fed45000-fed8ffff : pnp 00:01
fee00000-fee00fff : Local APIC
  fee00000-fee00fff : reserved
ff000000-ffffffff : reserved
100000000-12fffffff : System RAM

====================
The iomem of i386 stoakley is: 
--- stoakley.iomem.x86_64  2009-07-02 13:53:35.000000000 +0800
+++ stoakley.iomem.i386 2009-07-02 14:19:59.000000000 +0800
@@ -1,12 +1,15 @@
 00000000-0000ffff : reserved
 00010000-0009cbff : System RAM
 0009cc00-0009ffff : reserved
+000a0000-000bffff : Video RAM area
+000c0000-000cafff : Video ROM
 000cc000-000cffff : reserved
 000e0000-000fffff : reserved
+  000f0000-000fffff : System ROM
 00100000-cfefffff : System RAM
-  01000000-014eb53e : Kernel code
-  014eb53f-0177390f : Kernel data
-  01830000-018f583f : Kernel bss
+  00100000-00602876 : Kernel code
+  00602877-008e49db : Kernel data
+  00954000-009fe433 : Kernel bss
 cff00000-cff0afff : ACPI Tables
 cff0b000-cff0bfff : ACPI Non-volatile Storage
 cff0c000-cfffffff : reserved
@@ -50,7 +53,6 @@
   e0000000-efffffff : pnp 00:01
     e0000000-e07fffff : PCI MMCONFIG 0 [00-07]
 fe000000-fe01ffff : pnp 00:01
-  fe000000-fe01ffff : i5k_amb
 fe600000-fe6fffff : pnp 00:01
 fe700000-fe703fff : 0000:00:0f.0
 fec00000-fec0ffff : reserved
@@ -66,4 +68,3 @@
 fee00000-fee00fff : Local APIC
   fee00000-fee00fff : reserved
 ff000000-ffffffff : reserved
-100000000-12fffffff : System RAM


Alex 

On Thu, 2009-07-02 at 10:14 +0800, Yinghai Lu wrote:
> that looks strange...
> 
> config is 32bit. 
> 
> the second patch only do save and restore. and should be right right.
> 
> please check following patch on today's linus tree. and send out /proc/iomem
> 
> Thanks
> 
> Yinghai
> 
> [PATCH] x86: add boundary check for 32bit res before expand e820 resource to alignment
> 
> fix hang with HIGHMEM_64G and 32bit resource.
> according to hpa and Linus, use (resource_size_t)-1 to fend off big ranges.
> 
> analyized by hpa
> 
> Reported-and-tested-by: Mikael Pettersson <mikpe@it.uu.se>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> 
> ---
>  arch/x86/include/asm/proto.h |    3 ---
>  arch/x86/kernel/e820.c       |   20 ++++++++++++--------
>  include/linux/kernel.h       |    5 +++++
>  3 files changed, 17 insertions(+), 11 deletions(-)
> 
> Index: linux-2.6/arch/x86/kernel/e820.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/e820.c
> +++ linux-2.6/arch/x86/kernel/e820.c
> @@ -1367,9 +1367,9 @@ void __init e820_reserve_resources(void)
>  }
>  
>  /* How much should we pad RAM ending depending on where it is? */
> -static unsigned long ram_alignment(resource_size_t pos)
> +static u64 ram_alignment(u64 pos)
>  {
> -	unsigned long mb = pos >> 20;
> +	u64 mb = pos >> 20;
>  
>  	/* To 64kB in the first megabyte */
>  	if (!mb)
> @@ -1383,6 +1383,8 @@ static unsigned long ram_alignment(resou
>  	return 32*1024*1024;
>  }
>  
> +#define MAX_RESOURCE_SIZE ((resource_size_t)-1)
> +
>  void __init e820_reserve_resources_late(void)
>  {
>  	int i;
> @@ -1400,17 +1402,19 @@ void __init e820_reserve_resources_late(
>  	 * avoid stolen RAM:
>  	 */
>  	for (i = 0; i < e820.nr_map; i++) {
> -		struct e820entry *entry = &e820_saved.map[i];
> -		resource_size_t start, end;
> +		struct e820entry *entry = &e820.map[i];
> +		u64 start, end;
>  
>  		if (entry->type != E820_RAM)
>  			continue;
>  		start = entry->addr + entry->size;
> -		end = round_up(start, ram_alignment(start));
> -		if (start == end)
> +		end = round_up(start, ram_alignment(start)) - 1;
> +		if (end > MAX_RESOURCE_SIZE)
> +			end = MAX_RESOURCE_SIZE;
> +		if (start > end)
>  			continue;
> -		reserve_region_with_split(&iomem_resource, start,
> -						  end - 1, "RAM buffer");
> +		reserve_region_with_split(&iomem_resource, start, end,
> +					  "RAM buffer");
>  	}
>  }
>  

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Yinghai Lu]

Alex Shi wrote:
> The new patch works for my stoakley i386 machine. But for x86_64 machine
> the specjbb2005 still can not run with hugepage. The specjbb2005 use the
> same java setting as i386 system. After apply your patch, the iomem of
> x86_64 is:

please check

[PATCH] x86: don't clear nodes_states[N_NORMAL_MEMORY] when numa is not compiled in

Alex found:
for x86_64 machine the specjbb2005 still can not run with hugepage

only happens when numa is not compiled in

the root cause: node_set_state will not set it back for us in that case

so don't clear that when numa is not select in config

Reported-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/mm/init_64.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -598,8 +598,14 @@ void __init paging_init(void)
 
 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
 	sparse_init();
-	/* clear the default setting with node 0 */
+#if MAX_NUMNODES > 1
+	/*
+	 * clear the default setting with node 0
+	 * note: don't clear it, node_set_state will do nothing
+	 *	 (aka set it back) when numa support is not compiled in
+	 */
 	nodes_clear(node_states[N_NORMAL_MEMORY]);
+#endif
 	free_area_init_nodes(max_zone_pfns);
 }
 

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Christoph Lameter]

On Thu, 2 Jul 2009, Yinghai Lu wrote:

> Index: linux-2.6/arch/x86/mm/init_64.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/mm/init_64.c
> +++ linux-2.6/arch/x86/mm/init_64.c
> @@ -598,8 +598,14 @@ void __init paging_init(void)
>
>  	sparse_memory_present_with_active_regions(MAX_NUMNODES);
>  	sparse_init();
> -	/* clear the default setting with node 0 */
> +#if MAX_NUMNODES > 1
> +	/*
> +	 * clear the default setting with node 0
> +	 * note: don't clear it, node_set_state will do nothing
> +	 *	 (aka set it back) when numa support is not compiled in
> +	 */
>  	nodes_clear(node_states[N_NORMAL_MEMORY]);

The problem was that nodes_clear() does not fall back to a noop on !NUMA.
The node_set/clear_states() operations do become noops.

Could we make it more consistent by using only operations of the same
type? F.e. Add a node_clearall_states() in include/linux/nodemask.h that
falls back to a noop on !NUMA like the node_*_states operation?

Another options is to restore node_states[N_NORMAL_MEMORY] to its
initial condition. See the definition of node_states in page_alloc.c.

RE: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Shi, Alex]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="gb2312", Size: 2093 bytes --]

Yes, the patch fixes this bug! 

Alex 

>-----Original Message-----
>From: Yinghai Lu [mailto:yinghai@kernel.org]
>Sent: 2009Äê7ÔÂ2ÈÕ 16:51
>To: Shi, Alex; Andrew Morton; Ingo Molnar
>Cc: bugzilla-daemon@bugzilla.kernel.org; bugme-daemon@bugzilla.kernel.org;
>Christoph Lameter; Mel Gorman; linux-kernel@vger.kernel.org; Zhang, Yanmin;
>Chen, Tim C
>Subject: Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable
>on non-NUMA machine
>
>Alex Shi wrote:
>> The new patch works for my stoakley i386 machine. But for x86_64 machine
>> the specjbb2005 still can not run with hugepage. The specjbb2005 use the
>> same java setting as i386 system. After apply your patch, the iomem of
>> x86_64 is:
>
>please check
>
>[PATCH] x86: don't clear nodes_states[N_NORMAL_MEMORY] when numa is not
>compiled in
>
>Alex found:
>for x86_64 machine the specjbb2005 still can not run with hugepage
>
>only happens when numa is not compiled in
>
>the root cause: node_set_state will not set it back for us in that case
>
>so don't clear that when numa is not select in config
>
>Reported-by: Alex Shi <alex.shi@intel.com>
>Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>
>---
> arch/x86/mm/init_64.c |    8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
>Index: linux-2.6/arch/x86/mm/init_64.c
>===================================================================
>--- linux-2.6.orig/arch/x86/mm/init_64.c
>+++ linux-2.6/arch/x86/mm/init_64.c
>@@ -598,8 +598,14 @@ void __init paging_init(void)
>
> 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
> 	sparse_init();
>-	/* clear the default setting with node 0 */
>+#if MAX_NUMNODES > 1
>+	/*
>+	 * clear the default setting with node 0
>+	 * note: don't clear it, node_set_state will do nothing
>+	 *	 (aka set it back) when numa support is not compiled in
>+	 */
> 	nodes_clear(node_states[N_NORMAL_MEMORY]);
>+#endif
> 	free_area_init_nodes(max_zone_pfns);
> }
>
ÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥

[PATCH] x86: don't clear nodes_states[N_NORMAL_MEMORY] when numa is not compiled in -v2

[Yinghai Lu]

Alex found:
for x86_64 machine the specjbb2005 still can not run with hugepage

only happens when numa is not compiled in

the root cause: node_set_state will not set it back for us in that case

so don't clear that when numa is not select in config

v2: use node_clear_state instead

Reported-and-Tested-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/mm/init_64.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -598,8 +598,15 @@ void __init paging_init(void)
 
 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
 	sparse_init();
-	/* clear the default setting with node 0 */
-	nodes_clear(node_states[N_NORMAL_MEMORY]);
+
+	/*
+	 * clear the default setting with node 0
+	 * note: don't use nodes_clear here, that is really clearing when
+	 *	 numa support is not compiled in, and later node_set_state
+	 *	 will not set it back.
+	 */
+	node_clear_state(0, N_NORMAL_MEMORY);
+
 	free_area_init_nodes(max_zone_pfns);
 }
 

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Yinghai Lu]

Christoph Lameter wrote:
> On Thu, 2 Jul 2009, Yinghai Lu wrote:
> 
>> Index: linux-2.6/arch/x86/mm/init_64.c
>> ===================================================================
>> --- linux-2.6.orig/arch/x86/mm/init_64.c
>> +++ linux-2.6/arch/x86/mm/init_64.c
>> @@ -598,8 +598,14 @@ void __init paging_init(void)
>>
>>  	sparse_memory_present_with_active_regions(MAX_NUMNODES);
>>  	sparse_init();
>> -	/* clear the default setting with node 0 */
>> +#if MAX_NUMNODES > 1
>> +	/*
>> +	 * clear the default setting with node 0
>> +	 * note: don't clear it, node_set_state will do nothing
>> +	 *	 (aka set it back) when numa support is not compiled in
>> +	 */
>>  	nodes_clear(node_states[N_NORMAL_MEMORY]);
> 
> The problem was that nodes_clear() does not fall back to a noop on !NUMA.
> The node_set/clear_states() operations do become noops.
> 
> Could we make it more consistent by using only operations of the same
> type? F.e. Add a node_clearall_states() in include/linux/nodemask.h that
> falls back to a noop on !NUMA like the node_*_states operation?
> 
> Another options is to restore node_states[N_NORMAL_MEMORY] to its
> initial condition. See the definition of node_states in page_alloc.c.

could use node_clear_state(0, N_NORMAL_MEMORY) instead. because default one only have node 0 set in that mask.

YH

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Alex Shi]

Yinghai:

The 31-rc2 kernel still can not use hugepage on non-NUMA machine. And
this patch did not appear on rc2 kernel. Are there some concern about
this? 

BRG
Alex 


On Thu, 2009-07-02 at 16:50 +0800, Yinghai Lu wrote:
> Alex Shi wrote:
> > The new patch works for my stoakley i386 machine. But for x86_64 machine
> > the specjbb2005 still can not run with hugepage. The specjbb2005 use the
> > same java setting as i386 system. After apply your patch, the iomem of
> > x86_64 is:
> 
> please check
> 
> [PATCH] x86: don't clear nodes_states[N_NORMAL_MEMORY] when numa is not compiled in
> 
> Alex found:
> for x86_64 machine the specjbb2005 still can not run with hugepage
> 
> only happens when numa is not compiled in
> 
> the root cause: node_set_state will not set it back for us in that case
> 
> so don't clear that when numa is not select in config
> 
> Reported-by: Alex Shi <alex.shi@intel.com>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> 
> ---
>  arch/x86/mm/init_64.c |    8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6/arch/x86/mm/init_64.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/mm/init_64.c
> +++ linux-2.6/arch/x86/mm/init_64.c
> @@ -598,8 +598,14 @@ void __init paging_init(void)
>  
>  	sparse_memory_present_with_active_regions(MAX_NUMNODES);
>  	sparse_init();
> -	/* clear the default setting with node 0 */
> +#if MAX_NUMNODES > 1
> +	/*
> +	 * clear the default setting with node 0
> +	 * note: don't clear it, node_set_state will do nothing
> +	 *	 (aka set it back) when numa support is not compiled in
> +	 */
>  	nodes_clear(node_states[N_NORMAL_MEMORY]);
> +#endif
>  	free_area_init_nodes(max_zone_pfns);
>  }
>  

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Yinghai Lu]

Alex Shi wrote:
> Yinghai:
> 
> The 31-rc2 kernel still can not use hugepage on non-NUMA machine. And
> this patch did not appear on rc2 kernel. Are there some concern about
> this? 
> 

can you check
http://lkml.org/lkml/2009/7/2/326

YH

Re: [Bugme-new] [Bug 13690] New: nodes_clear cause hugepage unusable on non-NUMA machine

[Alex Shi]

On Tue, 2009-07-07 at 08:07 +0800, Yinghai Lu wrote:
> Alex Shi wrote:
> > Yinghai:
> > 
> > The 31-rc2 kernel still can not use hugepage on non-NUMA machine. And
> > this patch did not appear on rc2 kernel. Are there some concern about
> > this? 
> > 
> 
> can you check
> http://lkml.org/lkml/2009/7/2/326
> 
> YH

It works on my Stoakley i386 and x86_64 with latest Linus' kernel tree. 



Alex 

[PATCH] x86: don't clear nodes_states[N_NORMAL_MEMORY] when numa is not compiled in -v2

[Yinghai Lu]

Alex found:
for x86_64 machine the specjbb2005 still can not run with hugepage

only happens when numa is not compiled in

the root cause: node_set_state will not set it back for us in that case

so don't clear that when numa is not select in config

v2: use node_clear_state instead

Reported-and-Tested-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/mm/init_64.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -598,8 +598,15 @@ void __init paging_init(void)
 
 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
 	sparse_init();
-	/* clear the default setting with node 0 */
-	nodes_clear(node_states[N_NORMAL_MEMORY]);
+
+	/*
+	 * clear the default setting with node 0
+	 * note: don't use nodes_clear here, that is really clearing when
+	 *	 numa support is not compiled in, and later node_set_state
+	 *	 will not set it back.
+	 */
+	node_clear_state(0, N_NORMAL_MEMORY);
+
 	free_area_init_nodes(max_zone_pfns);
 }
 

Re: [PATCH] x86: don't clear nodes_states[N_NORMAL_MEMORY] when numa is not compiled in -v2

[Christoph Lameter]

Reviewed-by: Christoph Lameter <cl@linux-foundation.org>