Re: __vmalloc with GFP_ATOMIC causes 'sleeping from invalid context'

From: Nick Piggin
Date: Mon May 22 2006 - 02:10:03 EST

Nick Piggin wrote:
Giridhar Pemmasani wrote:

On Mon, 22 May 2006 11:53:55 +1000, Nick Piggin <nickpiggin@xxxxxxxxxxxx> 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.


SUSE Labs, Novell Inc.
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