Commit 9e695d2e authored by Committed by Linus Torvalds
sparc64: Support transparent huge pages.
This is relatively easy since PMD's now cover exactly 4MB of memory. Our PMD entries are 32-bits each, so we use a special encoding. The lowest bit, PMD_ISHUGE, determines the interpretation. This is possible because sparc64's page tables are purely software entities so we can use whatever encoding scheme we want. We just have to make the TLB miss assembler page table walkers aware of the layout. set_pmd_at() works much like set_pte_at() but it has to operate in two page from a table of non-huge PTEs, so we have to queue up TLB flushes based upon what mappings are valid in the PTE table. In the second regime we are going from huge-page to non-huge-page, and in that case we need only queue up a single TLB flush to push out the huge page mapping. We still have 5 bits remaining in the huge PMD encoding so we can very likely support any new pieces of THP state tracking that might get added in the future. With lots of help from Johannes Weiner. Signed-off-by: David S. Miller <firstname.lastname@example.org> Cc: Andrea Arcangeli <email@example.com> Cc: Johannes Weiner <firstname.lastname@example.org> Cc: Gerald Schaefer <email@example.com> Signed-off-by: Andrew Morton <firstname.lastname@example.org> Signed-off-by: Linus Torvalds <email@example.com>
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