[PATCH] __alloc_bootmem_node should not panic when it fails

[PATCH] __alloc_bootmem_node should not panic when it fails

[Anton Blanchard]

__alloc_bootmem_node currently panics if it cant satisfy an allocation
for a particular node. Thats rather antisocial, we should at the very
least return NULL and allow the caller to proceed (eg try another node).

A quick look at alloc_bootmem_node usage suggests we should fall back to
allocating from other nodes if it fails (as arch/alpha/kernel/pci_iommu.c
and arch/x86_64/kernel/setup64.c do).

The following patch does that. We fall back to the regular
__alloc_bootmem when __alloc_bootmem_node fails, which means all other
nodes are checked for available memory.

Signed-off-by: Anton Blanchard <anton@samba.org>

diff -puN mm/bootmem.c~debugit mm/bootmem.c
--- gr_work/mm/bootmem.c~debugit	2004-06-06 21:49:20.729826223 -0500
+++ gr_work-anton/mm/bootmem.c	2004-06-06 22:07:16.840243987 -0500
@@ -371,11 +371,6 @@ void * __init __alloc_bootmem_node (pg_d
 	if (ptr)
 		return (ptr);
 
-	/*
-	 * Whoops, we cannot satisfy the allocation request.
-	 */
-	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
-	panic("Out of memory");
-	return NULL;
+	return __alloc_bootmem(size, align, goal);
 }
 

_

Re: [PATCH] __alloc_bootmem_node should not panic when it fails

[Ingo Oeser]

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On Sunday 27 June 2004 07:27, Anton Blanchard wrote:
> The following patch does that. We fall back to the regular
> __alloc_bootmem when __alloc_bootmem_node fails, which means all other
> nodes are checked for available memory.
 
But allocating from other nodes has performance implications, which
might be quite big, depending on the specific architecture. So you
should at least print an KERN_INFO or even KERN_WARNING message, 
if this happens.

> Signed-off-by: Anton Blanchard <anton@samba.org>
> 
> diff -puN mm/bootmem.c~debugit mm/bootmem.c
> --- gr_work/mm/bootmem.c~debugit	2004-06-06 21:49:20.729826223 -0500
> +++ gr_work-anton/mm/bootmem.c	2004-06-06 22:07:16.840243987 -0500
> @@ -371,11 +371,6 @@ void * __init __alloc_bootmem_node (pg_d
>  	if (ptr)
>  		return (ptr);
>  
> -	/*
> -	 * Whoops, we cannot satisfy the allocation request.
> -	 */
> -	printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
Maybe changing this message to:
	printk(KERN_WARNING "Failed to alloc %lu bytes from local node.\n"
	" Allocating from distant node instead. Performance may drop!\n", size);

> -	panic("Out of memory");
> -	return NULL;
> +	return __alloc_bootmem(size, align, goal);
>  }

So now the user knows what is going on and that this node might need
more memory ;-)

Regards

Ingo Oeser

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Re: [PATCH] __alloc_bootmem_node should not panic when it fails

[Anton Blanchard]

> But allocating from other nodes has performance implications, which
> might be quite big, depending on the specific architecture. So you
> should at least print an KERN_INFO or even KERN_WARNING message, 
> if this happens.

...

> So now the user knows what is going on and that this node might need
> more memory ;-)

Unfortunately nodes without memory is relatively common on ppc64, and I
believe x86-64. From a ppc64 perspective Im fine with best effort, perhaps
someone from the heavily NUMA camp (ia64?) could comment.

Anton

Re: [PATCH] __alloc_bootmem_node should not panic when it fails

[Chris Wedgwood]

On Mon, Jun 28, 2004 at 08:28:03AM +1000, Anton Blanchard wrote:

> Unfortunately nodes without memory is relatively common on ppc64,
> and I believe x86-64. From a ppc64 perspective Im fine with best
> effort, perhaps someone from the heavily NUMA camp (ia64?) could
> comment.

Does anyone make ia64 NUMA hardware where you can have memory-less
nodes?


  --cw

Re: [PATCH] __alloc_bootmem_node should not panic when it fails

[Robert Picco]

Chris Wedgwood wrote:

>On Mon, Jun 28, 2004 at 08:28:03AM +1000, Anton Blanchard wrote:
>
>  
>
>>Unfortunately nodes without memory is relatively common on ppc64,
>>and I believe x86-64. From a ppc64 perspective Im fine with best
>>effort, perhaps someone from the heavily NUMA camp (ia64?) could
>>comment.
>>    
>>
>
>Does anyone make ia64 NUMA hardware where you can have memory-less
>nodes?
>
>
>  --cw
>
>  
>
HP ships IA64 NUMA hardware where the default memory configuration is 
memory-less.  There are N-1 cpu-nodes and 1 memory node.

Bob

Re: [PATCH] __alloc_bootmem_node should not panic when it fails

[Martin Hicks]

On Sun, Jun 27, 2004 at 11:29:12PM -0700, Chris Wedgwood wrote:
> On Mon, Jun 28, 2004 at 08:28:03AM +1000, Anton Blanchard wrote:
> 
> > Unfortunately nodes without memory is relatively common on ppc64,
> > and I believe x86-64. From a ppc64 perspective Im fine with best
> > effort, perhaps someone from the heavily NUMA camp (ia64?) could
> > comment.
> 
> Does anyone make ia64 NUMA hardware where you can have memory-less
> nodes?

Altix SN2 can have memoryless nodes

mh

-- 
Martin Hicks                Wild Open Source Inc.
mort@wildopensource.com     613-266-2296