• Zi Yan's avatar
    mm: thp: check pmd migration entry in common path · 84c3fc4e
    Zi Yan authored
    When THP migration is being used, memory management code needs to handle
    pmd migration entries properly.  This patch uses !pmd_present() or
    is_swap_pmd() (depending on whether pmd_none() needs separate code or
    not) to check pmd migration entries at the places where a pmd entry is
    present.
    
    Since pmd-related code uses split_huge_page(), split_huge_pmd(),
    pmd_trans_huge(), pmd_trans_unstable(), or
    pmd_none_or_trans_huge_or_clear_bad(), this patch:
    
    1. adds pmd migration entry split code in split_huge_pmd(),
    
    2. takes care of pmd migration entries whenever pmd_trans_huge() is present,
    
    3. makes pmd_none_or_trans_huge_or_clear_bad() pmd migration entry aware.
    
    Since split_huge_page() uses split_huge_pmd() and pmd_trans_unstable()
    is equivalent to pmd_none_or_trans_huge_or_clear_bad(), we do not change
    them.
    
    Until this commit, a pmd entry should be:
    1. pointing to a pte page,
    2. is_swap_pmd(),
    3. pmd_trans_huge(),
    4. pmd_devmap(), or
    5. pmd_none().
    Signed-off-by: default avatarZi Yan <zi.yan@cs.rutgers.edu>
    Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: David Nellans <dnellans@nvidia.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Mel Gorman <mgorman@techsingularity.net>
    Cc: Minchan Kim <minchan@kernel.org>
    Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Michal Hocko <mhocko@kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    84c3fc4e
mremap.c 17.1 KB