Re: [PATCH 06/10] percpu: kill percpu_alloc() and friends

From: Tony Luck <tony.luck@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: rusty@rustcorp.com.au, tglx@linutronix.de, x86@kernel.org,
	linux-kernel@vger.kernel.org, hpa@zytor.com, jeremy@goop.org,
	cpw@sgi.com, mingo@elte.hu
Subject: Re: [PATCH 06/10] percpu: kill percpu_alloc() and friends
Date: Wed, 11 Mar 2009 11:36:58 -0700	[thread overview]
Message-ID: <12c511ca0903111136h3805a106i484a32fd2972c568@mail.gmail.com> (raw)
In-Reply-To: <1234958676-27618-7-git-send-email-tj@kernel.org>

On Wed, Feb 18, 2009 at 5:04 AM, Tejun Heo <tj@kernel.org> wrote:
> +static inline void *__alloc_percpu(size_t size, size_t align)
>  {
> +       /*
> +        * Can't easily make larger alignment work with kmalloc.  WARN
> +        * on it.  Larger alignment should only be used for module
> +        * percpu sections on SMP for which this path isn't used.
> +        */
> +       WARN_ON_ONCE(align > __alignof__(unsigned long long));
>        return kzalloc(size, gfp);
>  }

This WARN_ON just pinged for me when I built & ran linux-next tag next-20090311

Stack trace from the WARN_ON pointed to __create_workqueue_key() which
does:

         wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);

and the cpu_workqueue_struct is defined as ____cacheline_aligned

I hit this on ia64, but all this code looks generic.

-Tony