mm: implement split page table lock for PMD level

The basic idea is the same as with PTE level: the lock is embedded into
struct page of table's page.

We can't use mm->pmd_huge_pte to store pgtables for THP, since we don't
take mm->page_table_lock anymore.  Let's reuse page->lru of table's page
for that.

pgtable_pmd_page_ctor() returns true, if initialization is successful
and false otherwise.  Current implementation never fails, but assumption
that constructor can fail will help to port it to -rt where spinlock_t
is rather huge and cannot be embedded into struct page -- dynamic
allocation is required.

Signed-off-by: Naoya Horiguchi <[email protected]>
Signed-off-by: Kirill A. Shutemov <[email protected]>
Tested-by: Alex Thorlton <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "Eric W . Biederman" <[email protected]>
Cc: "Paul E . McKenney" <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Jones <[email protected]>
Cc: David Howells <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michael Kerrisk <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Robin Holt <[email protected]>
Cc: Sedat Dilek <[email protected]>
Cc: Srikar Dronamraju <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Hugh Dickins <[email protected]>
Reviewed-by: Steven Rostedt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions