1. 03 Feb, 2012 38 commits
  2. 26 Jan, 2012 2 commits
    • Greg Kroah-Hartman's avatar
      Linux 3.2.2 · 3499d642
      Greg Kroah-Hartman authored
      3499d642
    • Hugh Dickins's avatar
      SHM_UNLOCK: fix Unevictable pages stranded after swap · 4556a6d9
      Hugh Dickins authored
      commit 24513264 upstream.
      
      Commit cc39c6a9 ("mm: account skipped entries to avoid looping in
      find_get_pages") correctly fixed an infinite loop; but left a problem
      that find_get_pages() on shmem would return 0 (appearing to callers to
      mean end of tree) when it meets a run of nr_pages swap entries.
      
      The only uses of find_get_pages() on shmem are via pagevec_lookup(),
      called from invalidate_mapping_pages(), and from shmctl SHM_UNLOCK's
      scan_mapping_unevictable_pages().  The first is already commented, and
      not worth worrying about; but the second can leave pages on the
      Unevictable list after an unusual sequence of swapping and locking.
      
      Fix that by using shmem_find_get_pages_and_swap() (then ignoring the
      swap) instead of pagevec_lookup().
      
      But I don't want to contaminate vmscan.c with shmem internals, nor
      shmem.c with LRU locking.  So move scan_mapping_unevictable_pages() into
      shmem.c, renaming it shmem_unlock_mapping(); and rename
      check_move_unevictable_page() to check_move_unevictable_pages(), looping
      down an array of pages, oftentimes under the same lock.
      
      Leave out the "rotate unevictable list" block: that's a leftover from
      when this was used for /proc/sys/vm/scan_unevictable_pages, whose flawed
      handling involved looking at pages at tail of LRU.
      
      Was there significance to the sequence first ClearPageUnevictable, then
      test page_evictable, then SetPageUnevictable here? I think not, we're
      under LRU lock, and have no barriers between those.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Shaohua Li <shaohua.li@intel.com>
      Cc: Eric Dumazet <eric.dumazet@gmail.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Michel Lespinasse <walken@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      
      4556a6d9