1. 26 Jul, 2016 2 commits
  2. 10 Oct, 2014 3 commits
    • Konstantin Khlebnikov's avatar
      mm/balloon_compaction: add vmstat counters and kpageflags bit · 09316c09
      Konstantin Khlebnikov authored
      Always mark pages with PageBalloon even if balloon compaction is disabled
      and expose this mark in /proc/kpageflags as KPF_BALLOON.
      Also this patch adds three counters into /proc/vmstat: "balloon_inflate",
      "balloon_deflate" and "balloon_migrate".  They accumulate balloon
      activity.  Current size of balloon is (balloon_inflate - balloon_deflate)
      All generic balloon code now gathered under option CONFIG_MEMORY_BALLOON.
      It should be selected by ballooning driver which wants use this feature.
      Currently virtio-balloon is the only user.
      Signed-off-by: default avatarKonstantin Khlebnikov <k.khlebnikov@samsung.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>
    • Konstantin Khlebnikov's avatar
      mm/balloon_compaction: remove balloon mapping and flag AS_BALLOON_MAP · 9d1ba805
      Konstantin Khlebnikov authored
      Now ballooned pages are detected using PageBalloon().  Fake mapping is no
      longer required.  This patch links ballooned pages to balloon device using
      field page->private instead of page->mapping.  Also this patch embeds
      balloon_dev_info directly into struct virtio_balloon.
      Signed-off-by: default avatarKonstantin Khlebnikov <k.khlebnikov@samsung.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>
    • Konstantin Khlebnikov's avatar
      mm/balloon_compaction: redesign ballooned pages management · d6d86c0a
      Konstantin Khlebnikov authored
      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
        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.
      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>
      Cc: <stable@vger.kernel.org>	[3.8+]
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
  3. 30 Sep, 2013 1 commit
    • Rafael Aquini's avatar
      mm: avoid reinserting isolated balloon pages into LRU lists · 117aad1e
      Rafael Aquini authored
      Isolated balloon pages can wrongly end up in LRU lists when
      migrate_pages() finishes its round without draining all the isolated
      page list.
      The same issue can happen when reclaim_clean_pages_from_list() tries to
      reclaim pages from an isolated page list, before migration, in the CMA
      path.  Such balloon page leak opens a race window against LRU lists
      shrinkers that leads us to the following kernel panic:
        BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
        IP: [<ffffffff810c2625>] shrink_page_list+0x24e/0x897
        PGD 3cda2067 PUD 3d713067 PMD 0
        Oops: 0000 [#1] SMP
        CPU: 0 PID: 340 Comm: kswapd0 Not tainted 3.12.0-rc1-22626-g4367597 #87
        Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
        RIP: shrink_page_list+0x24e/0x897
        RSP: 0000:ffff88003da499b8  EFLAGS: 00010286
        RAX: 0000000000000000 RBX: ffff88003e82bd60 RCX: 00000000000657d5
        RDX: 0000000000000000 RSI: 000000000000031f RDI: ffff88003e82bd40
        RBP: ffff88003da49ab0 R08: 0000000000000001 R09: 0000000081121a45
        R10: ffffffff81121a45 R11: ffff88003c4a9a28 R12: ffff88003e82bd40
        R13: ffff88003da0e800 R14: 0000000000000001 R15: ffff88003da49d58
        FS:  0000000000000000(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000
        CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
        CR2: 00000000067d9000 CR3: 000000003ace5000 CR4: 00000000000407b0
        Call Trace:
        Code: 80 7d 8f 01 48 83 95 68 ff ff ff 00 4c 89 e7 e8 5a 7b 00 00 48 85 c0 49 89 c5 75 08 80 7d 8f 00 74 3e eb 31 48 8b 80 18 01 00 00 <48> 8b 74 0d 48 8b 78 30 be 02 00 00 00 ff d2 eb
        RIP  [<ffffffff810c2625>] shrink_page_list+0x24e/0x897
         RSP <ffff88003da499b8>
        CR2: 0000000000000028
        ---[ end trace 703d2451af6ffbfd ]---
        Kernel panic - not syncing: Fatal exception
      This patch fixes the issue, by assuring the proper tests are made at
      putback_movable_pages() & reclaim_clean_pages_from_list() to avoid
      isolated balloon pages being wrongly reinserted in LRU lists.
      [akpm@linux-foundation.org: clarify awkward comment text]
      Signed-off-by: default avatarRafael Aquini <aquini@redhat.com>
      Reported-by: default avatarLuiz Capitulino <lcapitulino@redhat.com>
      Tested-by: default avatarLuiz Capitulino <lcapitulino@redhat.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
  4. 12 Dec, 2012 1 commit
    • Rafael Aquini's avatar
      mm: introduce a common interface for balloon pages mobility · 18468d93
      Rafael Aquini authored
      Memory fragmentation introduced by ballooning might reduce significantly
      the number of 2MB contiguous memory blocks that can be used within a guest,
      thus imposing performance penalties associated with the reduced number of
      transparent huge pages that could be used by the guest workload.
      This patch introduces a common interface to help a balloon driver on
      making its page set movable to compaction, and thus allowing the system
      to better leverage the compation efforts on memory defragmentation.
      [akpm@linux-foundation.org: use PAGE_FLAGS_CHECK_AT_PREP, s/__balloon_page_flags/page_flags_cleared/, small cleanups]
      [rientjes@google.com: allow balloon compaction for any system with memory compaction enabled, which is the defconfig]
      Signed-off-by: default avatarRafael Aquini <aquini@redhat.com>
      Acked-by: default avatarMel Gorman <mel@csn.ul.ie>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: "Michael S. Tsirkin" <mst@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Cc: Minchan Kim <minchan@kernel.org>
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>