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    SubjectRe: [block IO crash] Re: 2.6.39-rc5-git2 boot crashs
    On Wed, 4 May 2011, Linus Torvalds wrote:

    > On Wed, May 4, 2011 at 8:28 AM, Christoph Lameter <> wrote:
    > >
    > > There are no memory barriers used. The barrier() here is a compiler hint
    > > to not keep data across it.
    > Go back and read my email, please.
    > The lack of memory barriers is exactly what I worry about.
    > Look at the initialization path. The "tid" thing is _not_ purely cpu-local.

    kmem_cache_create() only hands the pointer to the slab cache back
    after the percpu values have been initialized. In order to do an allocation one
    needs to have the pointer to the slab cache.

    You think that accesses to struct kmem_cache_cpu by other cpus could
    require memory barriers? But this is what both SLAB and SLUB already do
    today even before these modification. Nor do we have memory barriers for
    the same situation in the page allocator.

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      Last update: 2011-05-04 18:11    [W:0.027 / U:13.680 seconds]
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