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    SubjectRe: [PATCH 2/2] Allow percpu variables to be page-aligned
    Date
    Jeremy Fitzhardinge <jeremy@goop.org> writes:

    > Let's allow page-alignment in general for per-cpu data (wanted by Xen, and
    > Ingo suggested KVM as well).
    >
    > Because larger alignments can use more room, we increase the max per-cpu
    > memory to 64k rather than 32k: it's getting a little tight.

    The second paragraph of the comment is dated. You are not changing the per-cpu
    memory size at all now.

    The code itself looks sane.

    Although we should probably fail the module load if the requested alignment
    is to great, but that is just picking nits, and is no worse than what we
    do today.

    Eric

    > ===================================================================
    > --- a/kernel/module.c
    > +++ b/kernel/module.c
    > @@ -346,10 +346,10 @@ static void *percpu_modalloc(unsigned lo
    > unsigned int i;
    > void *ptr;
    >
    > - if (align > SMP_CACHE_BYTES) {
    > - printk(KERN_WARNING "%s: per-cpu alignment %li > %i\n",
    > - name, align, SMP_CACHE_BYTES);
    > - align = SMP_CACHE_BYTES;
    > + if (align > PAGE_SIZE) {
    > + printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
    > + name, align, PAGE_SIZE);
    > + align = PAGE_SIZE;
    > }
    >
    > ptr = __per_cpu_start;
    -
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