1. 18 May, 2016 4 commits
  2. 16 May, 2016 4 commits
  3. 13 May, 2016 2 commits
    • Konstantin Khlebnikov's avatar
      mm/balloon_compaction: fix deflation when compaction is disabled · 1f649733
      Konstantin Khlebnikov authored
      commit 4d88e6f7 upstream.
      
      If CONFIG_BALLOON_COMPACTION=n balloon_page_insert() does not link pages
      with balloon and doesn't set PagePrivate flag, as a result
      balloon_page_dequeue() cannot get any pages because it thinks that all
      of them are isolated.  Without balloon compaction nobody can isolate
      ballooned pages.  It's safe to remove this check.
      
      Fixes: d6d86c0a ("mm/balloon_compaction: redesign ballooned pages management").
      Signed-off-by: default avatarKonstantin Khlebnikov <k.khlebnikov@samsung.com>
      Reported-by: default avatarMatt Mullins <mmullins@mmlx.us>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Cc: Gavin Guo <gavin.guo@canonical.com>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      1f649733
    • Konstantin Khlebnikov's avatar
      mm/balloon_compaction: redesign ballooned pages management · 33904d89
      Konstantin Khlebnikov authored
      commit d6d86c0a upstream.
      
      Sasha Levin reported KASAN splash inside isolate_migratepages_range().
      Problem is in the function __is_movable_balloon_page() which tests
      AS_BALLOON_MAP in page->mapping->flags.  This function has no protection
      against anonymous pages.  As result it tried to check address space flags
      inside struct anon_vma.
      
      Further investigation shows more problems in current implementation:
      
      * Special branch in __unmap_and_move() never works:
        balloon_page_movable() checks page flags and page_count.  In
        __unmap_and_move() page is locked, reference counter is elevated, thus
        balloon_page_movable() always fails.  As a result execution goes to the
        normal migration path.  virtballoon_migratepage() returns
        MIGRATEPAGE_BALLOON_SUCCESS instead of MIGRATEPAGE_SUCCESS,
        move_to_new_page() thinks this is an error code and assigns
        newpage->mapping to NULL.  Newly migrated page lose connectivity with
        balloon an all ability for further migration.
      
      * lru_lock erroneously required in isolate_migratepages_range() for
        isolation ballooned page.  This function releases lru_lock periodically,
        this makes migration mostly impossible for some pages.
      
      * balloon_page_dequeue have a tight race with balloon_page_isolate:
        balloon_page_isolate could be executed in parallel with dequeue between
        picking page from list and locking page_lock.  Race is rare because they
        use trylock_page() for locking.
      
      This patch fixes all of them.
      
      Instead of fake mapping with special flag this patch uses special state of
      page->_mapcount: PAGE_BALLOON_MAPCOUNT_VALUE = -256.  Buddy allocator uses
      PAGE_BUDDY_MAPCOUNT_VALUE = -128 for similar purpose.  Storing mark
      directly in struct page makes everything safer and easier.
      
      PagePrivate is used to mark pages present in page list (i.e.  not
      isolated, like PageLRU for normal pages).  It replaces special rules for
      reference counter and makes balloon migration similar to migration of
      normal pages.  This flag is protected by page_lock together with link to
      the balloon device.
      
      [js] backport to 3.12. MIGRATEPAGE_BALLOON_SUCCESS had to be removed
           from one more place. VM_BUG_ON_PAGE does not exist in 3.12 yet,
           use plain VM_BUG_ON.
      Signed-off-by: default avatarKonstantin Khlebnikov <k.khlebnikov@samsung.com>
      Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Link: http://lkml.kernel.org/p/53E6CEAA.9020105@oracle.com
      Cc: Rafael Aquini <aquini@redhat.com>
      Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Cc: Gavin Guo <gavin.guo@canonical.com>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      33904d89
  4. 11 May, 2016 20 commits
  5. 03 May, 2016 10 commits