1. 25 May, 2010 40 commits
    • KOSAKI Motohiro's avatar
      vmscan: page_check_references(): check low order lumpy reclaim properly · 5f53e762
      KOSAKI Motohiro authored
      If vmscan is under lumpy reclaim mode, it have to ignore referenced bit
      for making contenious free pages.  but current page_check_references()
      doesn't.
      
      Fix it.
      Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5f53e762
    • Huang Shijie's avatar
      readahead.c: fix comment · bf8abe8b
      Huang Shijie authored
      Fix a wrong comment over page_cache_async_readahead().
      Signed-off-by: default avatarHuang Shijie <shijie8@gmail.com>
      Acked-by: default avatarWu Fengguang <fengguang.wu@intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bf8abe8b
    • Shaohua Li's avatar
      vmscan: prevent get_scan_ratio() rounding errors · 76a33fc3
      Shaohua Li authored
      get_scan_ratio() calculates percentage and if the percentage is < 1%, it
      will round percentage down to 0% and cause we completely ignore scanning
      anon/file pages to reclaim memory even the total anon/file pages are very
      big.
      
      To avoid underflow, we don't use percentage, instead we directly calculate
      how many pages should be scaned.  In this way, we should get several
      scanned pages for < 1% percent.
      
      This has some benefits:
      
      1. increase our calculation precision
      
      2.  making our scan more smoothly.  Without this, if percent[x] is
         underflow, shrink_zone() doesn't scan any pages and suddenly it scans
         all pages when priority is zero.  With this, even priority isn't zero,
         shrink_zone() gets chance to scan some pages.
      
      Note, this patch doesn't really change logics, but just increase
      precision.  For system with a lot of memory, this might slightly changes
      behavior.  For example, in a sequential file read workload, without the
      patch, we don't swap any anon pages.  With it, if anon memory size is
      bigger than 16G, we will see one anon page swapped.  The 16G is calculated
      as PAGE_SIZE * priority(4096) * (fp/ap).  fp/ap is assumed to be 1024
      which is common in this workload.  So the impact sounds not a big deal.
      Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      76a33fc3
    • Greg Thelen's avatar
      mm: consider the entire user address space during node migration · 6ec3a127
      Greg Thelen authored
      Use mm->task_size instead of TASK_SIZE to ensure that the entire user
      address space is migrated.  mm->task_size is independent of the calling
      task context.  TASK SIZE may be dependant on the address space size of the
      calling process.  Usage of TASK_SIZE can lead to partial address space
      migration if the calling process was 32 bit and the migrating process was
      64 bit.
      
      Here is the test script used on 64 system with a 32 bit echo process:
      
        mount -t cgroup none /cgroup -o cpuset
        cd /cgroup
      
        mkdir 0
        echo 1 > 0/cpuset.cpus
        echo 0 > 0/cpuset.mems
        echo 1 > 0/cpuset.memory_migrate
      
        mkdir 1
        echo 1 > 1/cpuset.cpus
        echo 1 > 1/cpuset.mems
        echo 1 > 1/cpuset.memory_migrate
      
        echo $$ > 0/tasks
        64_bit_process &
        pid=$!
      
        echo $pid > 1/tasks   # This does not migrate all process pages without
                              # this patch.  If 64 bit echo is used or this patch is
                              # applied, then the full address space of $pid is
                              # migrated.
      
      To check memory migration, I watched:
        grep MemUsed /sys/devices/system/node/node*/meminfo
      Signed-off-by: default avatarGreg Thelen <gthelen@google.com>
      Acked-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
      Cc: Balbir Singh <balbir@in.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6ec3a127
    • Mel Gorman's avatar
      mm: compaction: defer compaction using an exponential backoff when compaction fails · 4f92e258
      Mel Gorman authored
      The fragmentation index may indicate that a failure is due to external
      fragmentation but after a compaction run completes, it is still possible
      for an allocation to fail.  There are two obvious reasons as to why
      
        o Page migration cannot move all pages so fragmentation remains
        o A suitable page may exist but watermarks are not met
      
      In the event of compaction followed by an allocation failure, this patch
      defers further compaction in the zone (1 << compact_defer_shift) times.
      If the next compaction attempt also fails, compact_defer_shift is
      increased up to a maximum of 6.  If compaction succeeds, the defer
      counters are reset again.
      
      The zone that is deferred is the first zone in the zonelist - i.e.  the
      preferred zone.  To defer compaction in the other zones, the information
      would need to be stored in the zonelist or implemented similar to the
      zonelist_cache.  This would impact the fast-paths and is not justified at
      this time.
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4f92e258
    • Mel Gorman's avatar
      mm: compaction: add a tunable that decides when memory should be compacted and... · 5e771905
      Mel Gorman authored
      mm: compaction: add a tunable that decides when memory should be compacted and when it should be reclaimed
      
      The kernel applies some heuristics when deciding if memory should be
      compacted or reclaimed to satisfy a high-order allocation.  One of these
      is based on the fragmentation.  If the index is below 500, memory will not
      be compacted.  This choice is arbitrary and not based on data.  To help
      optimise the system and set a sensible default for this value, this patch
      adds a sysctl extfrag_threshold.  The kernel will only compact memory if
      the fragmentation index is above the extfrag_threshold.
      
      [randy.dunlap@oracle.com: Fix build errors when proc fs is not configured]
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Signed-off-by: default avatarRandy Dunlap <randy.dunlap@oracle.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5e771905
    • Mel Gorman's avatar
      mm: compaction: direct compact when a high-order allocation fails · 56de7263
      Mel Gorman authored
      Ordinarily when a high-order allocation fails, direct reclaim is entered
      to free pages to satisfy the allocation.  With this patch, it is
      determined if an allocation failed due to external fragmentation instead
      of low memory and if so, the calling process will compact until a suitable
      page is freed.  Compaction by moving pages in memory is considerably
      cheaper than paging out to disk and works where there are locked pages or
      no swap.  If compaction fails to free a page of a suitable size, then
      reclaim will still occur.
      
      Direct compaction returns as soon as possible.  As each block is
      compacted, it is checked if a suitable page has been freed and if so, it
      returns.
      
      [akpm@linux-foundation.org: Fix build errors]
      [aarcange@redhat.com: fix count_vm_event preempt in memory compaction direct reclaim]
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      56de7263
    • Mel Gorman's avatar
      mm: compaction: add /sys trigger for per-node memory compaction · ed4a6d7f
      Mel Gorman authored
      Add a per-node sysfs file called compact.  When the file is written to,
      each zone in that node is compacted.  The intention that this would be
      used by something like a job scheduler in a batch system before a job
      starts so that the job can allocate the maximum number of hugepages
      without significant start-up cost.
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ed4a6d7f
    • Mel Gorman's avatar
      mm: compaction: add /proc trigger for memory compaction · 76ab0f53
      Mel Gorman authored
      Add a proc file /proc/sys/vm/compact_memory.  When an arbitrary value is
      written to the file, all zones are compacted.  The expected user of such a
      trigger is a job scheduler that prepares the system before the target
      application runs.
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      76ab0f53
    • Mel Gorman's avatar
      mm: compaction: memory compaction core · 748446bb
      Mel Gorman authored
      This patch is the core of a mechanism which compacts memory in a zone by
      relocating movable pages towards the end of the zone.
      
      A single compaction run involves a migration scanner and a free scanner.
      Both scanners operate on pageblock-sized areas in the zone.  The migration
      scanner starts at the bottom of the zone and searches for all movable
      pages within each area, isolating them onto a private list called
      migratelist.  The free scanner starts at the top of the zone and searches
      for suitable areas and consumes the free pages within making them
      available for the migration scanner.  The pages isolated for migration are
      then migrated to the newly isolated free pages.
      
      [aarcange@redhat.com: Fix unsafe optimisation]
      [mel@csn.ul.ie: do not schedule work on other CPUs for compaction]
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      748446bb
    • Mel Gorman's avatar
      mm: move definition for LRU isolation modes to a header · c175a0ce
      Mel Gorman authored
      Currently, vmscan.c defines the isolation modes for __isolate_lru_page().
      Memory compaction needs access to these modes for isolating pages for
      migration.  This patch exports them.
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Acked-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c175a0ce
    • Mel Gorman's avatar
      mm: export fragmentation index via debugfs · f1a5ab12
      Mel Gorman authored
      The fragmentation fragmentation index, is only meaningful if an allocation
      would fail and indicates what the failure is due to.  A value of -1 such
      as in many of the examples above states that the allocation would succeed.
       If it would fail, the value is between 0 and 1.  A value tending towards
      0 implies the allocation failed due to a lack of memory.  A value tending
      towards 1 implies it failed due to external fragmentation.
      
      For the most part, the huge page size will be the size of interest but not
      necessarily so it is exported on a per-order and per-zo basis via
      /sys/kernel/debug/extfrag/extfrag_index
      
      > cat /sys/kernel/debug/extfrag/extfrag_index
      Node 0, zone      DMA -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.00
      Node 0, zone   Normal -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 0.954
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f1a5ab12
    • Mel Gorman's avatar
      mm: export unusable free space index via debugfs · d7a5752c
      Mel Gorman authored
      The unusable free space index measures how much of the available free
      memory cannot be used to satisfy an allocation of a given size and is a
      value between 0 and 1.  The higher the value, the more of free memory is
      unusable and by implication, the worse the external fragmentation is.  For
      the most part, the huge page size will be the size of interest but not
      necessarily so it is exported on a per-order and per-zone basis via
      /sys/kernel/debug/extfrag/unusable_index.
      
      > cat /sys/kernel/debug/extfrag/unusable_index
      Node 0, zone      DMA 0.000 0.000 0.000 0.001 0.005 0.013 0.021 0.037 0.037 0.101 0.230
      Node 0, zone   Normal 0.000 0.000 0.000 0.001 0.002 0.002 0.005 0.015 0.028 0.028 0.054
      
      [akpm@linux-foundation.org: Fix allnoconfig]
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d7a5752c
    • Mel Gorman's avatar
      mm: migration: avoid race between shift_arg_pages() and rmap_walk() during... · a8bef8ff
      Mel Gorman authored
      mm: migration: avoid race between shift_arg_pages() and rmap_walk() during migration by not migrating temporary stacks
      
      Page migration requires rmap to be able to find all ptes mapping a page
      at all times, otherwise the migration entry can be instantiated, but it
      is possible to leave one behind if the second rmap_walk fails to find
      the page.  If this page is later faulted, migration_entry_to_page() will
      call BUG because the page is locked indicating the page was migrated by
      the migration PTE not cleaned up. For example
      
        kernel BUG at include/linux/swapops.h:105!
        invalid opcode: 0000 [#1] PREEMPT SMP
        ...
        Call Trace:
         [<ffffffff810e951a>] handle_mm_fault+0x3f8/0x76a
         [<ffffffff8130c7a2>] do_page_fault+0x44a/0x46e
         [<ffffffff813099b5>] page_fault+0x25/0x30
         [<ffffffff8114de33>] load_elf_binary+0x152a/0x192b
         [<ffffffff8111329b>] search_binary_handler+0x173/0x313
         [<ffffffff81114896>] do_execve+0x219/0x30a
         [<ffffffff8100a5c6>] sys_execve+0x43/0x5e
         [<ffffffff8100320a>] stub_execve+0x6a/0xc0
        RIP  [<ffffffff811094ff>] migration_entry_wait+0xc1/0x129
      
      There is a race between shift_arg_pages and migration that triggers this
      bug.  A temporary stack is setup during exec and later moved.  If
      migration moves a page in the temporary stack and the VMA is then removed
      before migration completes, the migration PTE may not be found leading to
      a BUG when the stack is faulted.
      
      This patch causes pages within the temporary stack during exec to be
      skipped by migration.  It does this by marking the VMA covering the
      temporary stack with an otherwise impossible combination of VMA flags.
      These flags are cleared when the temporary stack is moved to its final
      location.
      
      [kamezawa.hiroyu@jp.fujitsu.com: idea for having migration skip temporary stacks]
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a8bef8ff
    • Mel Gorman's avatar
      mm: allow CONFIG_MIGRATION to be set without CONFIG_NUMA or memory hot-remove · e9e96b39
      Mel Gorman authored
      CONFIG_MIGRATION currently depends on CONFIG_NUMA or on the architecture
      being able to hot-remove memory.  The main users of page migration such as
      sys_move_pages(), sys_migrate_pages() and cpuset process migration are
      only beneficial on NUMA so it makes sense.
      
      As memory compaction will operate within a zone and is useful on both NUMA
      and non-NUMA systems, this patch allows CONFIG_MIGRATION to be set if the
      user selects CONFIG_COMPACTION as an option.
      
      [akpm@linux-foundation.org: Depend on CONFIG_HUGETLB_PAGE]
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e9e96b39
    • Mel Gorman's avatar
      mm: migration: allow the migration of PageSwapCache pages · 3fe2011f
      Mel Gorman authored
      PageAnon pages that are unmapped may or may not have an anon_vma so are
      not currently migrated.  However, a swap cache page can be migrated and
      fits this description.  This patch identifies page swap caches and allows
      them to be migrated but ensures that no attempt to made to remap the pages
      would would potentially try to access an already freed anon_vma.
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3fe2011f
    • Mel Gorman's avatar
      mm: migration: do not try to migrate unmapped anonymous pages · 67b9509b
      Mel Gorman authored
      rmap_walk_anon() was triggering errors in memory compaction that look like
      use-after-free errors.  The problem is that between the page being
      isolated from the LRU and rcu_read_lock() being taken, the mapcount of the
      page dropped to 0 and the anon_vma gets freed.  This can happen during
      memory compaction if pages being migrated belong to a process that exits
      before migration completes.  Hence, the use-after-free race looks like
      
       1. Page isolated for migration
       2. Process exits
       3. page_mapcount(page) drops to zero so anon_vma was no longer reliable
       4. unmap_and_move() takes the rcu_lock but the anon_vma is already garbage
       4. call try_to_unmap, looks up tha anon_vma and "locks" it but the lock
          is garbage.
      
      This patch checks the mapcount after the rcu lock is taken.  If the
      mapcount is zero, the anon_vma is assumed to be freed and no further
      action is taken.
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      67b9509b
    • Mel Gorman's avatar
      mm: migration: share the anon_vma ref counts between KSM and page migration · 7f60c214
      Mel Gorman authored
      For clarity of review, KSM and page migration have separate refcounts on
      the anon_vma.  While clear, this is a waste of memory.  This patch gets
      KSM and page migration to share their toys in a spirit of harmony.
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Rik van Riel <riel@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7f60c214
    • Mel Gorman's avatar
      mm: migration: take a reference to the anon_vma before migrating · 3f6c8272
      Mel Gorman authored
      This patchset is a memory compaction mechanism that reduces external
      fragmentation memory by moving GFP_MOVABLE pages to a fewer number of
      pageblocks.  The term "compaction" was chosen as there are is a number of
      mechanisms that are not mutually exclusive that can be used to defragment
      memory.  For example, lumpy reclaim is a form of defragmentation as was
      slub "defragmentation" (really a form of targeted reclaim).  Hence, this
      is called "compaction" to distinguish it from other forms of
      defragmentation.
      
      In this implementation, a full compaction run involves two scanners
      operating within a zone - a migration and a free scanner.  The migration
      scanner starts at the beginning of a zone and finds all movable pages
      within one pageblock_nr_pages-sized area and isolates them on a
      migratepages list.  The free scanner begins at the end of the zone and
      searches on a per-area basis for enough free pages to migrate all the
      pages on the migratepages list.  As each area is respectively migrated or
      exhausted of free pages, the scanners are advanced one area.  A compaction
      run completes within a zone when the two scanners meet.
      
      This method is a bit primitive but is easy to understand and greater
      sophistication would require maintenance of counters on a per-pageblock
      basis.  This would have a big impact on allocator fast-paths to improve
      compaction which is a poor trade-off.
      
      It also does not try relocate virtually contiguous pages to be physically
      contiguous.  However, assuming transparent hugepages were in use, a
      hypothetical khugepaged might reuse compaction code to isolate free pages,
      split them and relocate userspace pages for promotion.
      
      Memory compaction can be triggered in one of three ways.  It may be
      triggered explicitly by writing any value to /proc/sys/vm/compact_memory
      and compacting all of memory.  It can be triggered on a per-node basis by
      writing any value to /sys/devices/system/node/nodeN/compact where N is the
      node ID to be compacted.  When a process fails to allocate a high-order
      page, it may compact memory in an attempt to satisfy the allocation
      instead of entering direct reclaim.  Explicit compaction does not finish
      until the two scanners meet and direct compaction ends if a suitable page
      becomes available that would meet watermarks.
      
      The series is in 14 patches.  The first three are not "core" to the series
      but are important pre-requisites.
      
      Patch 1 reference counts anon_vma for rmap_walk_anon(). Without this
      	patch, it's possible to use anon_vma after free if the caller is
      	not holding a VMA or mmap_sem for the pages in question. While
      	there should be no existing user that causes this problem,
      	it's a requirement for memory compaction to be stable. The patch
      	is at the start of the series for bisection reasons.
      Patch 2 merges the KSM and migrate counts. It could be merged with patch 1
      	but would be slightly harder to review.
      Patch 3 skips over unmapped anon pages during migration as there are no
      	guarantees about the anon_vma existing. There is a window between
      	when a page was isolated and migration started during which anon_vma
      	could disappear.
      Patch 4 notes that PageSwapCache pages can still be migrated even if they
      	are unmapped.
      Patch 5 allows CONFIG_MIGRATION to be set without CONFIG_NUMA
      Patch 6 exports a "unusable free space index" via debugfs. It's
      	a measure of external fragmentation that takes the size of the
      	allocation request into account. It can also be calculated from
      	userspace so can be dropped if requested
      Patch 7 exports a "fragmentation index" which only has meaning when an
      	allocation request fails. It determines if an allocation failure
      	would be due to a lack of memory or external fragmentation.
      Patch 8 moves the definition for LRU isolation modes for use by compaction
      Patch 9 is the compaction mechanism although it's unreachable at this point
      Patch 10 adds a means of compacting all of memory with a proc trgger
      Patch 11 adds a means of compacting a specific node with a sysfs trigger
      Patch 12 adds "direct compaction" before "direct reclaim" if it is
      	determined there is a good chance of success.
      Patch 13 adds a sysctl that allows tuning of the threshold at which the
      	kernel will compact or direct reclaim
      Patch 14 temporarily disables compaction if an allocation failure occurs
      	after compaction.
      
      Testing of compaction was in three stages.  For the test, debugging,
      preempt, the sleep watchdog and lockdep were all enabled but nothing nasty
      popped out.  min_free_kbytes was tuned as recommended by hugeadm to help
      fragmentation avoidance and high-order allocations.  It was tested on X86,
      X86-64 and PPC64.
      
      Ths first test represents one of the easiest cases that can be faced for
      lumpy reclaim or memory compaction.
      
      1. Machine freshly booted and configured for hugepage usage with
      	a) hugeadm --create-global-mounts
      	b) hugeadm --pool-pages-max DEFAULT:8G
      	c) hugeadm --set-recommended-min_free_kbytes
      	d) hugeadm --set-recommended-shmmax
      
      	The min_free_kbytes here is important. Anti-fragmentation works best
      	when pageblocks don't mix. hugeadm knows how to calculate a value that
      	will significantly reduce the worst of external-fragmentation-related
      	events as reported by the mm_page_alloc_extfrag tracepoint.
      
      2. Load up memory
      	a) Start updatedb
      	b) Create in parallel a X files of pagesize*128 in size. Wait
      	   until files are created. By parallel, I mean that 4096 instances
      	   of dd were launched, one after the other using &. The crude
      	   objective being to mix filesystem metadata allocations with
      	   the buffer cache.
      	c) Delete every second file so that pageblocks are likely to
      	   have holes
      	d) kill updatedb if it's still running
      
      	At this point, the system is quiet, memory is full but it's full with
      	clean filesystem metadata and clean buffer cache that is unmapped.
      	This is readily migrated or discarded so you'd expect lumpy reclaim
      	to have no significant advantage over compaction but this is at
      	the POC stage.
      
      3. In increments, attempt to allocate 5% of memory as hugepages.
      	   Measure how long it took, how successful it was, how many
      	   direct reclaims took place and how how many compactions. Note
      	   the compaction figures might not fully add up as compactions
      	   can take place for orders other than the hugepage size
      
      X86				vanilla		compaction
      Final page count                    913                916 (attempted 1002)
      pages reclaimed                   68296               9791
      
      X86-64				vanilla		compaction
      Final page count:                   901                902 (attempted 1002)
      Total pages reclaimed:           112599              53234
      
      PPC64				vanilla		compaction
      Final page count:                    93                 94 (attempted 110)
      Total pages reclaimed:           103216              61838
      
      There was not a dramatic improvement in success rates but it wouldn't be
      expected in this case either.  What was important is that fewer pages were
      reclaimed in all cases reducing the amount of IO required to satisfy a
      huge page allocation.
      
      The second tests were all performance related - kernbench, netperf, iozone
      and sysbench.  None showed anything too remarkable.
      
      The last test was a high-order allocation stress test.  Many kernel
      compiles are started to fill memory with a pressured mix of unmovable and
      movable allocations.  During this, an attempt is made to allocate 90% of
      memory as huge pages - one at a time with small delays between attempts to
      avoid flooding the IO queue.
      
                                                   vanilla   compaction
      Percentage of request allocated X86               98           99
      Percentage of request allocated X86-64            95           98
      Percentage of request allocated PPC64             55           70
      
      This patch:
      
      rmap_walk_anon() does not use page_lock_anon_vma() for looking up and
      locking an anon_vma and it does not appear to have sufficient locking to
      ensure the anon_vma does not disappear from under it.
      
      This patch copies an approach used by KSM to take a reference on the
      anon_vma while pages are being migrated.  This should prevent rmap_walk()
      running into nasty surprises later because anon_vma has been freed.
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3f6c8272
    • David Rientjes's avatar
      mm: default to node zonelist ordering when nodes have only lowmem · e325c90f
      David Rientjes authored
      There are two types of zonelist ordering methodologies:
      
       - node order, preferring allocations on a node to stay local to and
      
       - zone order, preferring allocations come from a higher zone to avoid
         allocating in lowmem zones even though they may not be local.
      
      The ordering technique used by the kernel is configurable on the command
      line, but also has some logic to determine what the default should be.
      
      This logic currently lacks knowledge of systems where a node may only have
      lowmem.  For such systems, it is necessary to use node order so that
      GFP_KERNEL allocations may be satisfied by nodes consisting of only
      lowmem.
      
      If zone order is used, GFP_KERNEL allocations to such nodes are actually
      allocated on a node with local affinity that includes ZONE_NORMAL.
      
      This change defaults to node zonelist ordering if any node lacks
      ZONE_NORMAL.
      
      To force zone order, append 'numa_zonelist_order=zone' to the kernel
      command line.
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Acked-by: default avatarMel Gorman <mel@csn.ul.ie>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e325c90f
    • Naoya Horiguchi's avatar
      pagemap: add #ifdefs CONFIG_HUGETLB_PAGE on code walking hugetlb vma · 1a5cb814
      Naoya Horiguchi authored
      If !CONFIG_HUGETLB_PAGE, pagemap_hugetlb_range() is never called.  So put
      it (and its calling function) into #ifdef block.
      Signed-off-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Acked-by: default avatarMatt Mackall <mpm@selenic.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1a5cb814
    • Johannes Weiner's avatar
      mincore: do nested page table walks · e48293fd
      Johannes Weiner authored
      Do page table walks with the well-known nested loops we use in several
      other places already.
      
      This avoids doing full page table walks after every pte range and also
      allows to handle unmapped areas bigger than one pte range in one go.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e48293fd
    • Johannes Weiner's avatar
      mincore: pass ranges as start,end address pairs · 25ef0e50
      Johannes Weiner authored
      Instead of passing a start address and a number of pages into the helper
      functions, convert them to use a start and an end address.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      25ef0e50
    • Johannes Weiner's avatar
      mincore: break do_mincore() into logical pieces · f4884010
      Johannes Weiner authored
      Split out functions to handle hugetlb ranges, pte ranges and unmapped
      ranges, to improve readability but also to prepare the file structure for
      nested page table walks.
      
      No semantic changes intended.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f4884010
    • Johannes Weiner's avatar
      mincore: cleanups · 6a60f1b3
      Johannes Weiner authored
      This fixes some minor issues that bugged me while going over the code:
      
      o adjust argument order of do_mincore() to match the syscall
      o simplify range length calculation
      o drop superfluous shift in huge tlb calculation, address is page aligned
      o drop dead nr_huge calculation
      o check pte_none() before pte_present()
      o comment and whitespace fixes
      
      No semantic changes intended.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6a60f1b3
    • Miao Xie's avatar
      cpuset,mm: fix no node to alloc memory when changing cpuset's mems · c0ff7453
      Miao Xie authored
      Before applying this patch, cpuset updates task->mems_allowed and
      mempolicy by setting all new bits in the nodemask first, and clearing all
      old unallowed bits later.  But in the way, the allocator may find that
      there is no node to alloc memory.
      
      The reason is that cpuset rebinds the task's mempolicy, it cleans the
      nodes which the allocater can alloc pages on, for example:
      
      (mpol: mempolicy)
      	task1			task1's mpol	task2
      	alloc page		1
      	  alloc on node0? NO	1
      				1		change mems from 1 to 0
      				1		rebind task1's mpol
      				0-1		  set new bits
      				0	  	  clear disallowed bits
      	  alloc on node1? NO	0
      	  ...
      	can't alloc page
      	  goto oom
      
      This patch fixes this problem by expanding the nodes range first(set newly
      allowed bits) and shrink it lazily(clear newly disallowed bits).  So we
      use a variable to tell the write-side task that read-side task is reading
      nodemask, and the write-side task clears newly disallowed nodes after
      read-side task ends the current memory allocation.
      
      [akpm@linux-foundation.org: fix spello]
      Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: Paul Menage <menage@google.com>
      Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
      Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Ravikiran Thirumalai <kiran@scalex86.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: Andi Kleen <andi@firstfloor.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c0ff7453
    • Miao Xie's avatar
      mempolicy: restructure rebinding-mempolicy functions · 708c1bbc
      Miao Xie authored
      Nick Piggin reported that the allocator may see an empty nodemask when
      changing cpuset's mems[1].  It happens only on the kernel that do not do
      atomic nodemask_t stores.  (MAX_NUMNODES > BITS_PER_LONG)
      
      But I found that there is also a problem on the kernel that can do atomic
      nodemask_t stores.  The problem is that the allocator can't find a node to
      alloc page when changing cpuset's mems though there is a lot of free
      memory.  The reason is like this:
      
      (mpol: mempolicy)
      	task1			task1's mpol	task2
      	alloc page		1
      	  alloc on node0? NO	1
      				1		change mems from 1 to 0
      				1		rebind task1's mpol
      				0-1		  set new bits
      				0	  	  clear disallowed bits
      	  alloc on node1? NO	0
      	  ...
      	can't alloc page
      	  goto oom
      
      I can use the attached program reproduce it by the following step:
      
      # mkdir /dev/cpuset
      # mount -t cpuset cpuset /dev/cpuset
      # mkdir /dev/cpuset/1
      # echo `cat /dev/cpuset/cpus` > /dev/cpuset/1/cpus
      # echo `cat /dev/cpuset/mems` > /dev/cpuset/1/mems
      # echo $$ > /dev/cpuset/1/tasks
      # numactl --membind=`cat /dev/cpuset/mems` ./cpuset_mem_hog <nr_tasks> &
         <nr_tasks> = max(nr_cpus - 1, 1)
      # killall -s SIGUSR1 cpuset_mem_hog
      # ./change_mems.sh
      
      several hours later, oom will happen though there is a lot of free memory.
      
      This patchset fixes this problem by expanding the nodes range first(set
      newly allowed bits) and shrink it lazily(clear newly disallowed bits).  So
      we use a variable to tell the write-side task that read-side task is
      reading nodemask, and the write-side task clears newly disallowed nodes
      after read-side task ends the current memory allocation.
      
      This patch:
      
      In order to fix no node to alloc memory, when we want to update mempolicy
      and mems_allowed, we expand the set of nodes first (set all the newly
      nodes) and shrink the set of nodes lazily(clean disallowed nodes), But the
      mempolicy's rebind functions may breaks the expanding.
      
      So we restructure the mempolicy's rebind functions and split the rebind
      work to two steps, just like the update of cpuset's mems: The 1st step:
      expand the set of the mempolicy's nodes.  The 2nd step: shrink the set of
      the mempolicy's nodes.  It is used when there is no real lock to protect
      the mempolicy in the read-side.  Otherwise we can do rebind work at once.
      
      In order to implement it, we define
      
      	enum mpol_rebind_step {
      		MPOL_REBIND_ONCE,
      		MPOL_REBIND_STEP1,
      		MPOL_REBIND_STEP2,
      		MPOL_REBIND_NSTEP,
      	};
      
      If the mempolicy needn't be updated by two steps, we can pass
      MPOL_REBIND_ONCE to the rebind functions.  Or we can pass
      MPOL_REBIND_STEP1 to do the first step of the rebind work and pass
      MPOL_REBIND_STEP2 to do the second step work.
      
      Besides that, it maybe long time between these two step and we have to
      release the lock that protects mempolicy and mems_allowed.  If we hold the
      lock once again, we must check whether the current mempolicy is under the
      rebinding (the first step has been done) or not, because the task may
      alloc a new mempolicy when we don't hold the lock.  So we defined the
      following flag to identify it:
      
      #define MPOL_F_REBINDING (1 << 2)
      
      The new functions will be used in the next patch.
      Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: Paul Menage <menage@google.com>
      Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
      Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Ravikiran Thirumalai <kiran@scalex86.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: Andi Kleen <andi@firstfloor.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      708c1bbc
    • Lee Schermerhorn's avatar
      mempolicy: document cpuset interaction with tmpfs mpol mount option · 971ada0f
      Lee Schermerhorn authored
      Update Documentation/filesystems/tmpfs.txt to describe the interaction of
      tmpfs mount option memory policy with tasks' cpuset mems_allowed.
      
      Note: the mount(8) man page [in the util-linux-ng package] requires
      similiar updates.
      Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
      Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Ravikiran Thirumalai <kiran@scalex86.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: David Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      971ada0f
    • Lee Schermerhorn's avatar
      mempolicy: factor mpol_shared_policy_init() return paths · 15d77835
      Lee Schermerhorn authored
      Factor out duplicate put/frees in mpol_shared_policy_init() to a common
      return path.
      Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
      Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Ravikiran Thirumalai <kiran@scalex86.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: David Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      15d77835
    • Lee Schermerhorn's avatar
      mempolicy: rename policy_types and cleanup initialization · 345ace9c
      Lee Schermerhorn authored
      Rename 'policy_types[]' to 'policy_modes[]' to better match the array
      contents.
      
      Use designated intializer syntax for policy_modes[].
      Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
      Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Ravikiran Thirumalai <kiran@scalex86.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: David Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      345ace9c
    • Lee Schermerhorn's avatar
      mempolicy: lose unnecessary loop variable in mpol_parse_str() · b4652e84
      Lee Schermerhorn authored
      We don't really need the extra variable 'i' in mpol_parse_str().  The only
      use is as the the loop variable.  Then, it's assigned to 'mode'.  Just use
      mode, and loose the 'uninitialized_var()' macro.
      Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
      Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Ravikiran Thirumalai <kiran@scalex86.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: David Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b4652e84
    • Lee Schermerhorn's avatar
      mempolicy: don't call mpol_set_nodemask() when no_context · e17f74af
      Lee Schermerhorn authored
      No need to call mpol_set_nodemask() when we have no context for the
      mempolicy.  This can occur when we're parsing a tmpfs 'mpol' mount option.
       Just save the raw nodemask in the mempolicy's w.user_nodemask member for
      use when a tmpfs/shmem file is created.  mpol_shared_policy_init() will
      "contextualize" the policy for the new file based on the creating task's
      context.
      Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
      Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Ravikiran Thirumalai <kiran@scalex86.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: David Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e17f74af
    • Bob Liu's avatar
      mempolicy: remove redundant check · 19800502
      Bob Liu authored
      Lee's patch "mempolicy: use MPOL_PREFERRED for system-wide default policy"
      has made the MPOL_DEFAULT only used in the memory policy APIs.  So, no
      need to check in __mpol_equal also.  Also get rid of mpol_match_intent()
      and move its logic directly into __mpol_equal().
      Signed-off-by: default avatarBob Liu <lliubbo@gmail.com>
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      19800502
    • Bob Liu's avatar
      mempolicy: remove case MPOL_INTERLEAVE from policy_zonelist() · 6eb27e1f
      Bob Liu authored
      In policy_zonelist() mode MPOL_INTERLEAVE shouldn't happen, so fall
      through to BUG() instead of break to return.  I also fixed the comment.
      Signed-off-by: default avatarBob Liu <lliubbo@gmail.com>
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6eb27e1f
    • Bob Liu's avatar
      mempolicy: remove redundant code · 6d556294
      Bob Liu authored
      1.  In funtion is_valid_nodemask(), varibable k will be inited to 0 in
         the following loop, needn't init to policy_zone anymore.
      
      2. (MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES) has already defined
         to MPOL_MODE_FLAGS in mempolicy.h.
      Signed-off-by: default avatarBob Liu <lliubbo@gmail.com>
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6d556294
    • Minchan Kim's avatar
      mm: remove return value of putback_lru_pages() · e13861d8
      Minchan Kim authored
      putback_lru_page() never can fail.  So it doesn't matter count of "the
      number of pages put back".
      
      In addition, users of this functions don't use return value.
      
      Let's remove unnecessary code.
      Signed-off-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e13861d8
    • Huang Shijie's avatar
      shmem: remove redundant code · 4b50dc26
      Huang Shijie authored
      prep_new_page() will call set_page_private(page, 0) to initialise the
      page, so the code is redundant.
      Signed-off-by: default avatarHuang Shijie <shijie8@gmail.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Acked-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4b50dc26
    • Yinghai Lu's avatar
      sparsemem: on no vmemmap path put mem_map on node high too · e48e67e0
      Yinghai Lu authored
      We need to put mem_map high when virtual memmap is not used.
      
      before this patch
      free mem pfn range on first node:
      [    0.000000]  19 - 1f
      [    0.000000]  28 40 - 80 95
      [    0.000000]  702 740 - 1000 1000
      [    0.000000]  347c - 347e
      [    0.000000]  34e7 3500 - 3b80 3b8b
      [    0.000000]  73b8b 73bc0 - 73c00 73c00
      [    0.000000]  73ddd - 73e00
      [    0.000000]  73fdd - 74000
      [    0.000000]  741dd - 74200
      [    0.000000]  743dd - 74400
      [    0.000000]  745dd - 74600
      [    0.000000]  747dd - 74800
      [    0.000000]  749dd - 74a00
      [    0.000000]  74bdd - 74c00
      [    0.000000]  74ddd - 74e00
      [    0.000000]  74fdd - 75000
      [    0.000000]  751dd - 75200
      [    0.000000]  753dd - 75400
      [    0.000000]  755dd - 75600
      [    0.000000]  757dd - 75800
      [    0.000000]  759dd - 75a00
      [    0.000000]  79bdd 79c00 - 7d540 7d550
      [    0.000000]  7f745 - 7f750
      [    0.000000]  10000b 100040 - 2080000 2080000
      so only 79c00 - 7d540 are major free block under 4g...
      
      after this patch, we will get
      [    0.000000]  19 - 1f
      [    0.000000]  28 40 - 80 95
      [    0.000000]  702 740 - 1000 1000
      [    0.000000]  347c - 347e
      [    0.000000]  34e7 3500 - 3600 3600
      [    0.000000]  37dd - 3800
      [    0.000000]  39dd - 3a00
      [    0.000000]  3bdd - 3c00
      [    0.000000]  3ddd - 3e00
      [    0.000000]  3fdd - 4000
      [    0.000000]  41dd - 4200
      [    0.000000]  43dd - 4400
      [    0.000000]  45dd - 4600
      [    0.000000]  47dd - 4800
      [    0.000000]  49dd - 4a00
      [    0.000000]  4bdd - 4c00
      [    0.000000]  4ddd - 4e00
      [    0.000000]  4fdd - 5000
      [    0.000000]  51dd - 5200
      [    0.000000]  53dd - 5400
      [    0.000000]  95dd 9600 - 7d540 7d550
      [    0.000000]  7f745 - 7f750
      [    0.000000]  17000b 170040 - 2080000 2080000
      we will have 9600 - 7d540 for major free block...
      
      sparse-vmemmap path already used __alloc_bootmem_node_high()
      Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
      Cc: Jiri Slaby <jirislaby@gmail.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e48e67e0
    • Corrado Zoccolo's avatar
      page allocator: reduce fragmentation in buddy allocator by adding buddies that... · 6dda9d55
      Corrado Zoccolo authored
      page allocator: reduce fragmentation in buddy allocator by adding buddies that are merging to the tail of the free lists
      
      In order to reduce fragmentation, this patch classifies freed pages in two
      groups according to their probability of being part of a high order merge.
       Pages belonging to a compound whose next-highest buddy is free are more
      likely to be part of a high order merge in the near future, so they will
      be added at the tail of the freelist.  The remaining pages are put at the
      front of the freelist.
      
      In this way, the pages that are more likely to cause a big merge are kept
      free longer.  Consequently there is a tendency to aggregate the
      long-living allocations on a subset of the compounds, reducing the
      fragmentation.
      
      This heuristic was tested on three machines, x86, x86-64 and ppc64 with
      3GB of RAM in each machine.  The tests were kernbench, netperf, sysbench
      and STREAM for performance and a high-order stress test for huge page
      allocations.
      
      KernBench X86
      Elapsed mean     374.77 ( 0.00%)   375.10 (-0.09%)
      User    mean     649.53 ( 0.00%)   650.44 (-0.14%)
      System  mean      54.75 ( 0.00%)    54.18 ( 1.05%)
      CPU     mean     187.75 ( 0.00%)   187.25 ( 0.27%)
      
      KernBench X86-64
      Elapsed mean      94.45 ( 0.00%)    94.01 ( 0.47%)
      User    mean     323.27 ( 0.00%)   322.66 ( 0.19%)
      System  mean      36.71 ( 0.00%)    36.50 ( 0.57%)
      CPU     mean     380.75 ( 0.00%)   381.75 (-0.26%)
      
      KernBench PPC64
      Elapsed mean     173.45 ( 0.00%)   173.74 (-0.17%)
      User    mean     587.99 ( 0.00%)   587.95 ( 0.01%)
      System  mean      60.60 ( 0.00%)    60.57 ( 0.05%)
      CPU     mean     373.50 ( 0.00%)   372.75 ( 0.20%)
      
      Nothing notable for kernbench.
      
      NetPerf UDP X86
            64    42.68 ( 0.00%)     42.77 ( 0.21%)
           128    85.62 ( 0.00%)     85.32 (-0.35%)
           256   170.01 ( 0.00%)    168.76 (-0.74%)
          1024   655.68 ( 0.00%)    652.33 (-0.51%)
          2048  1262.39 ( 0.00%)   1248.61 (-1.10%)
          3312  1958.41 ( 0.00%)   1944.61 (-0.71%)
          4096  2345.63 ( 0.00%)   2318.83 (-1.16%)
          8192  4132.90 ( 0.00%)   4089.50 (-1.06%)
         16384  6770.88 ( 0.00%)   6642.05 (-1.94%)*
      
      NetPerf UDP X86-64
            64   148.82 ( 0.00%)    154.92 ( 3.94%)
           128   298.96 ( 0.00%)    312.95 ( 4.47%)
           256   583.67 ( 0.00%)    626.39 ( 6.82%)
          1024  2293.18 ( 0.00%)   2371.10 ( 3.29%)
          2048  4274.16 ( 0.00%)   4396.83 ( 2.79%)
          3312  6356.94 ( 0.00%)   6571.35 ( 3.26%)
          4096  7422.68 ( 0.00%)   7635.42 ( 2.79%)*
          8192 12114.81 ( 0.00%)* 12346.88 ( 1.88%)
         16384 17022.28 ( 0.00%)* 17033.19 ( 0.06%)*
                   1.64%             2.73%
      
      NetPerf UDP PPC64
            64    49.98 ( 0.00%)     50.25 ( 0.54%)
           128    98.66 ( 0.00%)    100.95 ( 2.27%)
           256   197.33 ( 0.00%)    191.03 (-3.30%)
          1024   761.98 ( 0.00%)    785.07 ( 2.94%)
          2048  1493.50 ( 0.00%)   1510.85 ( 1.15%)
          3312  2303.95 ( 0.00%)   2271.72 (-1.42%)
          4096  2774.56 ( 0.00%)   2773.06 (-0.05%)
          8192  4918.31 ( 0.00%)   4793.59 (-2.60%)
         16384  7497.98 ( 0.00%)   7749.52 ( 3.25%)
      
      The tests are run to have confidence limits within 1%.  Results marked
      with a * were not confident although in this case, it's only outside by
      small amounts.  Even with some results that were not confident, the
      netperf UDP results were generally positive.
      
      NetPerf TCP X86
            64   652.25 ( 0.00%)*   648.12 (-0.64%)*
                  23.80%            22.82%
           128  1229.98 ( 0.00%)*  1220.56 (-0.77%)*
                  21.03%            18.90%
           256  2105.88 ( 0.00%)   1872.03 (-12.49%)*
                   1.00%            16.46%
          1024  3476.46 ( 0.00%)*  3548.28 ( 2.02%)*
                  13.37%            11.39%
          2048  4023.44 ( 0.00%)*  4231.45 ( 4.92%)*
                   9.76%            12.48%
          3312  4348.88 ( 0.00%)*  4396.96 ( 1.09%)*
                   6.49%             8.75%
          4096  4726.56 ( 0.00%)*  4877.71 ( 3.10%)*
                   9.85%             8.50%
          8192  4732.28 ( 0.00%)*  5777.77 (18.10%)*
                   9.13%            13.04%
         16384  5543.05 ( 0.00%)*  5906.24 ( 6.15%)*
                   7.73%             8.68%
      
      NETPERF TCP X86-64
                  netperf-tcp-vanilla-netperf       netperf-tcp
                         tcp-vanilla     pgalloc-delay
            64  1895.87 ( 0.00%)*  1775.07 (-6.81%)*
                   5.79%             4.78%
           128  3571.03 ( 0.00%)*  3342.20 (-6.85%)*
                   3.68%             6.06%
           256  5097.21 ( 0.00%)*  4859.43 (-4.89%)*
                   3.02%             2.10%
          1024  8919.10 ( 0.00%)*  8892.49 (-0.30%)*
                   5.89%             6.55%
          2048 10255.46 ( 0.00%)* 10449.39 ( 1.86%)*
                   7.08%             7.44%
          3312 10839.90 ( 0.00%)* 10740.15 (-0.93%)*
                   6.87%             7.33%
          4096 10814.84 ( 0.00%)* 10766.97 (-0.44%)*
                   6.86%             8.18%
          8192 11606.89 ( 0.00%)* 11189.28 (-3.73%)*
                   7.49%             5.55%
         16384 12554.88 ( 0.00%)* 12361.22 (-1.57%)*
                   7.36%             6.49%
      
      NETPERF TCP PPC64
                  netperf-tcp-vanilla-netperf       netperf-tcp
                         tcp-vanilla     pgalloc-delay
            64   594.17 ( 0.00%)    596.04 ( 0.31%)*
                   1.00%             2.29%
           128  1064.87 ( 0.00%)*  1074.77 ( 0.92%)*
                   1.30%             1.40%
           256  1852.46 ( 0.00%)*  1856.95 ( 0.24%)
                   1.25%             1.00%
          1024  3839.46 ( 0.00%)*  3813.05 (-0.69%)
                   1.02%             1.00%
          2048  4885.04 ( 0.00%)*  4881.97 (-0.06%)*
                   1.15%             1.04%
          3312  5506.90 ( 0.00%)   5459.72 (-0.86%)
          4096  6449.19 ( 0.00%)   6345.46 (-1.63%)
          8192  7501.17 ( 0.00%)   7508.79 ( 0.10%)
         16384  9618.65 ( 0.00%)   9490.10 (-1.35%)
      
      There was a distinct lack of confidence in the X86* figures so I included
      what the devation was where the results were not confident.  Many of the
      results, whether gains or losses were within the standard deviation so no
      solid conclusion can be reached on performance impact.  Looking at the
      figures, only the X86-64 ones look suspicious with a few losses that were
      outside the noise.  However, the results were so unstable that without
      knowing why they vary so much, a solid conclusion cannot be reached.
      
      SYSBENCH X86
                    sysbench-vanilla     pgalloc-delay
                 1  7722.85 ( 0.00%)  7756.79 ( 0.44%)
                 2 14901.11 ( 0.00%) 13683.44 (-8.90%)
                 3 15171.71 ( 0.00%) 14888.25 (-1.90%)
                 4 14966.98 ( 0.00%) 15029.67 ( 0.42%)
                 5 14370.47 ( 0.00%) 14865.00 ( 3.33%)
                 6 14870.33 ( 0.00%) 14845.57 (-0.17%)
                 7 14429.45 ( 0.00%) 14520.85 ( 0.63%)
                 8 14354.35 ( 0.00%) 14362.31 ( 0.06%)
      
      SYSBENCH X86-64
                 1 17448.70 ( 0.00%) 17484.41 ( 0.20%)
                 2 34276.39 ( 0.00%) 34251.00 (-0.07%)
                 3 50805.25 ( 0.00%) 50854.80 ( 0.10%)
                 4 66667.10 ( 0.00%) 66174.69 (-0.74%)
                 5 66003.91 ( 0.00%) 65685.25 (-0.49%)
                 6 64981.90 ( 0.00%) 65125.60 ( 0.22%)
                 7 64933.16 ( 0.00%) 64379.23 (-0.86%)
                 8 63353.30 ( 0.00%) 63281.22 (-0.11%)
                 9 63511.84 ( 0.00%) 63570.37 ( 0.09%)
                10 62708.27 ( 0.00%) 63166.25 ( 0.73%)
                11 62092.81 ( 0.00%) 61787.75 (-0.49%)
                12 61330.11 ( 0.00%) 61036.34 (-0.48%)
                13 61438.37 ( 0.00%) 61994.47 ( 0.90%)
                14 62304.48 ( 0.00%) 62064.90 (-0.39%)
                15 63296.48 ( 0.00%) 62875.16 (-0.67%)
                16 63951.76 ( 0.00%) 63769.09 (-0.29%)
      
      SYSBENCH PPC64
                                   -sysbench-pgalloc-delay-sysbench
                    sysbench-vanilla     pgalloc-delay
                 1  7645.08 ( 0.00%)  7467.43 (-2.38%)
                 2 14856.67 ( 0.00%) 14558.73 (-2.05%)
                 3 21952.31 ( 0.00%) 21683.64 (-1.24%)
                 4 27946.09 ( 0.00%) 28623.29 ( 2.37%)
                 5 28045.11 ( 0.00%) 28143.69 ( 0.35%)
                 6 27477.10 ( 0.00%) 27337.45 (-0.51%)
                 7 26489.17 ( 0.00%) 26590.06 ( 0.38%)
                 8 26642.91 ( 0.00%) 25274.33 (-5.41%)
                 9 25137.27 ( 0.00%) 24810.06 (-1.32%)
                10 24451.99 ( 0.00%) 24275.85 (-0.73%)
                11 23262.20 ( 0.00%) 23674.88 ( 1.74%)
                12 24234.81 ( 0.00%) 23640.89 (-2.51%)
                13 24577.75 ( 0.00%) 24433.50 (-0.59%)
                14 25640.19 ( 0.00%) 25116.52 (-2.08%)
                15 26188.84 ( 0.00%) 26181.36 (-0.03%)
                16 26782.37 ( 0.00%) 26255.99 (-2.00%)
      
      Again, there is little to conclude here.  While there are a few losses,
      the results vary by +/- 8% in some cases.  They are the results of most
      concern as there are some large losses but it's also within the variance
      typically seen between kernel releases.
      
      The STREAM results varied so little and are so verbose that I didn't
      include them here.
      
      The final test stressed how many huge pages can be allocated.  The
      absolute number of huge pages allocated are the same with or without the
      page.  However, the "unusability free space index" which is a measure of
      external fragmentation was slightly lower (lower is better) throughout the
      lifetime of the system.  I also measured the latency of how long it took
      to successfully allocate a huge page.  The latency was slightly lower and
      on X86 and PPC64, more huge pages were allocated almost immediately from
      the free lists.  The improvement is slight but there.
      
      [mel@csn.ul.ie: Tested, reworked for less branches]
      [czoccolo@gmail.com: fix oops by checking pfn_valid_within()]
      Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
      Cc: Corrado Zoccolo <czoccolo@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6dda9d55
    • KOSAKI Motohiro's avatar
      tmpfs: insert tmpfs cache pages to inactive list at first · e9d6c157
      KOSAKI Motohiro authored
      Shaohua Li reported parallel file copy on tmpfs can lead to OOM killer.
      This is regression of caused by commit 9ff473b9 ("vmscan: evict
      streaming IO first").  Wow, It is 2 years old patch!
      
      Currently, tmpfs file cache is inserted active list at first.  This means
      that the insertion doesn't only increase numbers of pages in anon LRU, but
      it also reduces anon scanning ratio.  Therefore, vmscan will get totally
      confused.  It scans almost only file LRU even though the system has plenty
      unused tmpfs pages.
      
      Historically, lru_cache_add_active_anon() was used for two reasons.
      1) Intend to priotize shmem page rather than regular file cache.
      2) Intend to avoid reclaim priority inversion of used once pages.
      
      But we've lost both motivation because (1) Now we have separate anon and
      file LRU list.  then, to insert active list doesn't help such priotize.
      (2) In past, one pte access bit will cause page activation.  then to
      insert inactive list with pte access bit mean higher priority than to
      insert active list.  Its priority inversion may lead to uninteded lru
      chun.  but it was already solved by commit 64574746 (vmscan: detect
      mapped file pages used only once).  (Thanks Hannes, you are great!)
      
      Thus, now we can use lru_cache_add_anon() instead.
      Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reported-by: default avatarShaohua Li <shaohua.li@intel.com>
      Reviewed-by: default avatarWu Fengguang <fengguang.wu@intel.com>
      Reviewed-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Acked-by: default avatarHugh Dickins <hughd@google.com>
      Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
      Cc: <stable@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e9d6c157