Re: [PATCH,RFC] Add gfp_mask to get_vm_area()

[Russell King <rmk@arm.linux.org.uk>]

On Tue, Oct 01, 2002 at 03:34:17PM +1000, David Gibson wrote:
> I don't see an easy one: PPC 4xx has non-coherent cache, so we have to
> mark consistent memory non-cacheable.  We want to make the normal
> lowmem mapping use large page TLB entries, so we can't frob the
> attribute bits on the pages in place.  That means we need to create a
> new, non-cacheable mapping for the physical RAM we allocate, which in
> turn means allocating a chunk of kernel virtual memory.

Same problem on ARM.  I just haven't got the motivation to rewrite the
bits of the kernel that need to be rewritten to make it work.

Have you checked that your pte/pmd allocation functions can be called
from IRQ context as well?

You basically need:

 - irq-safe get_vm_area
 - irq-safe pmd_alloc_kernel
 - irq-safe pte_alloc_kernel

Last time I looked, all the above were not irq-safe.

-- 
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html