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Message-ID: <447155E5.8060406@yahoo.com.au>
Date: Mon, 22 May 2006 16:10:45 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Giridhar Pemmasani <giri@lmc.cs.sunysb.edu>
CC: linux-kernel@vger.kernel.org
Subject: Re: __vmalloc with GFP_ATOMIC causes 'sleeping from invalid context'
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Nick Piggin wrote:
> Giridhar Pemmasani wrote:
> 
>> On Mon, 22 May 2006 11:53:55 +1000, Nick Piggin 
>> <nickpiggin@yahoo.com.au> said:
>>
>>    > Giridhar Pemmasani wrote:
>>   >> If __vmalloc is called in atomic context with GFP_ATOMIC flags,
>>   >> __get_vm_area_node is called, which calls kmalloc_node with
>>   >> GFP_KERNEL flags. This causes 'sleeping function called from
>>   >> invalid context at mm/slab.c:2729' with 2.6.16-rc4 kernel. A
>>   >> simple solution is to use
>>
>>    > I can't see what would cause this in either 2.6.16-rc4 or
>>    > 2.6.17-rc4.  What is the line?
>>
>> If someone calls __vmalloc in atomic context (with GFP_ATOMIC flags):
> 
> 
> OK I misunderstood your comment. I was looking for the caller.
> Hmm, page_alloc.c does, but I don't know that it needs to be
> atomic -- what happens if we just make that allocation GFP_KERNEL?
> 

OTOH, it doesn't seem to be particularly wrong to allow __vmalloc
GFP_ATOMIC allocations. The correct fix is to pass the gfp_mask
to kmalloc: if you're worried about breaking the API, introduce a
new __get_vm_area_node_mask() and implement __get_vm_area_node()
as a simple wrapper that passes in GFP_KERNEL.

Thanks,
Nick

-- 
SUSE Labs, Novell Inc.
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