Re: [patch 03/41] cpu alloc: Use cpu allocator instead of the builtin modules per cpu allocator

Andrew Morton
2008-05-30T05:00:07Z

On Thu, 29 May 2008 20:56:23 -0700 Christoph Lameter <clameter@sgi.com> wrote:

> Remove the builtin per cpu allocator from modules.c and use cpu_alloc instead.
>
> The patch also removes PERCPU_ENOUGH_ROOM. The size of the cpu_alloc area is
> determined by CONFIG_CPU_AREA_SIZE. PERCPU_ENOUGH_ROOMs default was 8k.
> CONFIG_CPU_AREA_SIZE defaults to 30k. Thus we have more space to load modules.
>
>
> ...
>
> + unsigned long align = sechdrs[pcpuindex].sh_addralign;
> + unsigned long size = sechdrs[pcpuindex].sh_size;
> +
> + if (align > PAGE_SIZE) {
> + printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
> + mod->name, align, PAGE_SIZE);

Indenting broke.

Alas, PAGE_SIZE has, iirc, unsigned type on some architectures and
unsigned long on others. I suspect you'll need to cast it to be able
to print it.

> + align = PAGE_SIZE;
> + }
> + percpu = cpu_alloc(size, GFP_KERNEL|__GFP_ZERO, align);
> + if (!percpu)
> + printk(KERN_WARNING "Could not allocate %lu bytes percpu data\n",

80-col bustage,.

A printk like this should, I think, identify what part of the kernel it
came from.

But really, I don't think any printk should be present here.
cpu_alloc() itself should dump the warning and the backtrace when it
runs out. Because a cpu_alloc() failure is a major catastrophe. It
probably means a reconfigure-and-reboot cycle.

Right now it means a
reconfigure-kernel-rebuild-kernel-reinstall-kernel-then-reboot cycle.
Or a call-vendor-complain-pay-money-and-wait cycle. But I hope we can
fix that with the boot parameter thing?