| Date | Thu, 17 Oct 2013 19:13:38 +0000 | From | Christoph Lameter <> | Subject | Re: [PATCH v2 13/15] slab: use struct page for slab management |
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On Wed, 16 Oct 2013, Joonsoo Kim wrote:
> - * see PAGE_MAPPING_ANON below. > - */ > + union { > + struct address_space *mapping; /* If low bit clear, points to > + * inode address_space, or NULL. > + * If page mapped as anonymous > + * memory, low bit is set, and > + * it points to anon_vma object: > + * see PAGE_MAPPING_ANON below. > + */ > + void *s_mem; /* slab first object */ > + };
The overloading of mapping has caused problems in the past since slab pages are (or are they no longer?) used for DMA to disk. At that point the I/O subsystem may be expecting a mapping in the page struct if this field is not NULL.
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