Re: [S+Q 09/16] [percpu] make allocpercpu usable during early boot

[Pekka Enberg <penberg@cs.helsinki.fi>]

On Sat, Jun 26, 2010 at 12:20 AM, Christoph Lameter
<cl@linux-foundation.org> wrote:
> allocpercpu() may be used during early boot after the page allocator
> has been bootstrapped but when interrupts are still off. Make sure
> that we do not do GFP_KERNEL allocations if this occurs.
>
> Cc: tj@kernel.org
> Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
>
> ---
>  mm/percpu.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/mm/percpu.c
> ===================================================================
> --- linux-2.6.orig/mm/percpu.c  2010-06-23 14:43:54.000000000 -0500
> +++ linux-2.6/mm/percpu.c       2010-06-23 14:44:05.000000000 -0500
> @@ -275,7 +275,8 @@ static void __maybe_unused pcpu_next_pop
>  * memory is always zeroed.
>  *
>  * CONTEXT:
> - * Does GFP_KERNEL allocation.
> + * Does GFP_KERNEL allocation (May be called early in boot when
> + * interrupts are still disabled. Will then do GFP_NOWAIT alloc).
>  *
>  * RETURNS:
>  * Pointer to the allocated area on success, NULL on failure.
> @@ -286,7 +287,7 @@ static void *pcpu_mem_alloc(size_t size)
>                return NULL;
>
>        if (size <= PAGE_SIZE)
> -               return kzalloc(size, GFP_KERNEL);
> +               return kzalloc(size, GFP_KERNEL & gfp_allowed_mask);
>        else {
>                void *ptr = vmalloc(size);
>                if (ptr)

This looks wrong to me. All slab allocators should do gfp_allowed_mask
magic under the hood. Maybe it's triggering kmalloc_large() path that
needs the masking too?

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