Re: [patch] slab: always follow arch requested alignments

Pekka Enberg wrote:

Hi Christoph,

On 7/26/06, Christoph Lameter <[email protected]> wrote:

We intentionally discard the caller mandated alignment for debugging
purposes.

There are two different types of alignment:
- SLAB_HWCACHE_ALIGN: it's a recommendation, it's regularly ignored.

- the align parameter, or ARCH_SLAB_MINALIGN: It's mandatory. For example the pgd structures must be 4 kB aligned, it's required by the hardware. And I think there was (is?) a structure where ptr & ~(size-1) was used to find the start of the structure.

Thus the patch is correct, it's a bug in the slab allocator. If HWCACHE_ALIGN is set, then the allocator ignores align or ARCH_SLAB_MINALIGN.

--
   Manfred
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