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    SubjectRe: [patch 03/41] cpu alloc: Use cpu allocator instead of the builtin modules per cpu allocator
    On Thu, 29 May 2008 22:14:17 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:

    > On Thu, 29 May 2008, Andrew Morton wrote:
    >
    > > > + printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
    > > > + mod->name, align, PAGE_SIZE);
    > >
    > > Indenting broke.
    >
    > Hmmm. Okay.
    >
    > > 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.
    >
    > This is code that was moved.
    >
    > > > + 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.
    >
    > Again moved code. Should I really do string separations for code
    > that is moved?

    That's not a string separation - it is a functional improvement.

    Sure, why not fix these little things while we're there?

    > > 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.
    >
    > The code has been able to deal with an allocpercpu failure in the
    > past. Why would it have trouble with a cpu_alloc failure here?

    Because an alloc_percpu failure is a page allocator failure. This is a
    well-known situation which we know basically never happens, or at least
    happens under well-known circumstances.

    Whereas a cpu_alloc() failure is a dead box. We cannot fix it via
    running page reclaim. We cannot fix it via oom-killing someone. We
    are dead.


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