Martin Schwidefsky 78fb907626 s390/mm: simplify page table alloc/free code ...

With the removal of the dynamic reallocation of page tables for
KVM (see git commit 0b46e0a3ec)
the page table allocation / freeing code can be simplified.

The page table free code can now use the alloc_pgste bit in the
mm context to decide if a page table is 2K or 4K, there is no mix
of different sized page tables anymore. This eliminates the need
to use "page->_mapcount == 0" to check for 4K page table.

Use the lower two bits in page->_mapcount to indicate which
2K fragments of the 4K page are in use.

As 31-bit support is gone, remove the two defines ALLOC_ORDER
and FRAG_MASK and use the constants directly where appropriate.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2015-08-19 10:41:19 +02:00

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