• Kirill A. Shutemov's avatar
    thp, mlock: do not allow huge pages in mlocked area · 7479df6d
    Kirill A. Shutemov authored
    With new refcounting THP can belong to several VMAs.  This makes tricky
    to track THP pages, when they partially mlocked.  It can lead to leaking
    mlocked pages to non-VM_LOCKED vmas and other problems.
    
    With this patch we will split all pages on mlock and avoid
    fault-in/collapse new THP in VM_LOCKED vmas.
    
    I've tried alternative approach: do not mark THP pages mlocked and keep
    them on normal LRUs.  This way vmscan could try to split huge pages on
    memory pressure and free up subpages which doesn't belong to VM_LOCKED
    vmas.  But this is user-visible change: we screw up Mlocked accouting
    reported in meminfo, so I had to leave this approach aside.
    
    We can bring something better later, but this should be good enough for
    now.
    Signed-off-by: 's avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Tested-by: 's avatarSasha Levin <sasha.levin@oracle.com>
    Tested-by: 's avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Acked-by: 's avatarJerome Marchand <jmarchan@redhat.com>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Cc: Steve Capper <steve.capper@linaro.org>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Michal Hocko <mhocko@suse.cz>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: David Rientjes <rientjes@google.com>
    Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
    7479df6d
mlock.c 20.4 KB