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    hugetlb, rmap: add reverse mapping for hugepage · 0fe6e20b
    Naoya Horiguchi 提交于
    This patch adds reverse mapping feature for hugepage by introducing
    mapcount for shared/private-mapped hugepage and anon_vma for
    private-mapped hugepage.
    
    While hugepage is not currently swappable, reverse mapping can be useful
    for memory error handler.
    
    Without this patch, memory error handler cannot identify processes
    using the bad hugepage nor unmap it from them. That is:
    - for shared hugepage:
      we can collect processes using a hugepage through pagecache,
      but can not unmap the hugepage because of the lack of mapcount.
    - for privately mapped hugepage:
      we can neither collect processes nor unmap the hugepage.
    This patch solves these problems.
    
    This patch include the bug fix given by commit 23be7468, so reverts it.
    
    Dependency:
      "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h"
    
    ChangeLog since May 24.
    - create hugetlb_inline.h and move is_vm_hugetlb_index() in it.
    - move functions setting up anon_vma for hugepage into mm/rmap.c.
    
    ChangeLog since May 13.
    - rebased to 2.6.34
    - fix logic error (in case that private mapping and shared mapping coexist)
    - move is_vm_hugetlb_page() into include/linux/mm.h to use this function
      from linear_page_index()
    - define and use linear_hugepage_index() instead of compound_order()
    - use page_move_anon_rmap() in hugetlb_cow()
    - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart.
    - revert commit 24be7468 completely
    Signed-off-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Cc: Andi Kleen <andi@firstfloor.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Mel Gorman <mel@csn.ul.ie>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Larry Woodman <lwoodman@redhat.com>
    Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
    Acked-by: NFengguang Wu <fengguang.wu@intel.com>
    Acked-by: NMel Gorman <mel@csn.ul.ie>
    Signed-off-by: NAndi Kleen <ak@linux.intel.com>
    0fe6e20b
hugetlb.c 73.1 KB