1. 04 Jun, 2014 40 commits
    • Mel Gorman's avatar
      mm: avoid unnecessary atomic operations during end_page_writeback() · 888cf2db
      Mel Gorman authored
      If a page is marked for immediate reclaim then it is moved to the tail of
      the LRU list.  This occurs when the system is under enough memory pressure
      for pages under writeback to reach the end of the LRU but we test for this
      using atomic operations on every writeback.  This patch uses an optimistic
      non-atomic test first.  It'll miss some pages in rare cases but the
      consequences are not severe enough to warrant such a penalty.
      
      While the function does not dominate profiles during a simple dd test the
      cost of it is reduced.
      
      73048     0.7428  vmlinux-3.15.0-rc5-mmotm-20140513 end_page_writeback
      23740     0.2409  vmlinux-3.15.0-rc5-lessatomic     end_page_writeback
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      888cf2db
    • Mel Gorman's avatar
      mm: page_alloc: calculate classzone_idx once from the zonelist ref · d8846374
      Mel Gorman authored
      There is no need to calculate zone_idx(preferred_zone) multiple times
      or use the pgdat to figure it out.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Dan Carpenter <dan.carpenter@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d8846374
    • Mel Gorman's avatar
      mm: non-atomically mark page accessed during page cache allocation where possible · 2457aec6
      Mel Gorman authored
      aops->write_begin may allocate a new page and make it visible only to have
      mark_page_accessed called almost immediately after.  Once the page is
      visible the atomic operations are necessary which is noticable overhead
      when writing to an in-memory filesystem like tmpfs but should also be
      noticable with fast storage.  The objective of the patch is to initialse
      the accessed information with non-atomic operations before the page is
      visible.
      
      The bulk of filesystems directly or indirectly use
      grab_cache_page_write_begin or find_or_create_page for the initial
      allocation of a page cache page.  This patch adds an init_page_accessed()
      helper which behaves like the first call to mark_page_accessed() but may
      called before the page is visible and can be done non-atomically.
      
      The primary APIs of concern in this care are the following and are used
      by most filesystems.
      
      	find_get_page
      	find_lock_page
      	find_or_create_page
      	grab_cache_page_nowait
      	grab_cache_page_write_begin
      
      All of them are very similar in detail to the patch creates a core helper
      pagecache_get_page() which takes a flags parameter that affects its
      behavior such as whether the page should be marked accessed or not.  Then
      old API is preserved but is basically a thin wrapper around this core
      function.
      
      Each of the filesystems are then updated to avoid calling
      mark_page_accessed when it is known that the VM interfaces have already
      done the job.  There is a slight snag in that the timing of the
      mark_page_accessed() has now changed so in rare cases it's possible a page
      gets to the end of the LRU as PageReferenced where as previously it might
      have been repromoted.  This is expected to be rare but it's worth the
      filesystem people thinking about it in case they see a problem with the
      timing change.  It is also the case that some filesystems may be marking
      pages accessed that previously did not but it makes sense that filesystems
      have consistent behaviour in this regard.
      
      The test case used to evaulate this is a simple dd of a large file done
      multiple times with the file deleted on each iterations.  The size of the
      file is 1/10th physical memory to avoid dirty page balancing.  In the
      async case it will be possible that the workload completes without even
      hitting the disk and will have variable results but highlight the impact
      of mark_page_accessed for async IO.  The sync results are expected to be
      more stable.  The exception is tmpfs where the normal case is for the "IO"
      to not hit the disk.
      
      The test machine was single socket and UMA to avoid any scheduling or NUMA
      artifacts.  Throughput and wall times are presented for sync IO, only wall
      times are shown for async as the granularity reported by dd and the
      variability is unsuitable for comparison.  As async results were variable
      do to writback timings, I'm only reporting the maximum figures.  The sync
      results were stable enough to make the mean and stddev uninteresting.
      
      The performance results are reported based on a run with no profiling.
      Profile data is based on a separate run with oprofile running.
      
      async dd
                                          3.15.0-rc3            3.15.0-rc3
                                             vanilla           accessed-v2
      ext3    Max      elapsed     13.9900 (  0.00%)     11.5900 ( 17.16%)
      tmpfs	Max      elapsed      0.5100 (  0.00%)      0.4900 (  3.92%)
      btrfs   Max      elapsed     12.8100 (  0.00%)     12.7800 (  0.23%)
      ext4	Max      elapsed     18.6000 (  0.00%)     13.3400 ( 28.28%)
      xfs	Max      elapsed     12.5600 (  0.00%)      2.0900 ( 83.36%)
      
      The XFS figure is a bit strange as it managed to avoid a worst case by
      sheer luck but the average figures looked reasonable.
      
              samples percentage
      ext3       86107    0.9783  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
      ext3       23833    0.2710  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
      ext3        5036    0.0573  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
      ext4       64566    0.8961  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
      ext4        5322    0.0713  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
      ext4        2869    0.0384  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
      xfs        62126    1.7675  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
      xfs         1904    0.0554  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
      xfs          103    0.0030  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
      btrfs      10655    0.1338  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
      btrfs       2020    0.0273  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
      btrfs        587    0.0079  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
      tmpfs      59562    3.2628  vmlinux-3.15.0-rc4-vanilla        mark_page_accessed
      tmpfs       1210    0.0696  vmlinux-3.15.0-rc4-accessed-v3r25 init_page_accessed
      tmpfs         94    0.0054  vmlinux-3.15.0-rc4-accessed-v3r25 mark_page_accessed
      
      [akpm@linux-foundation.org: don't run init_page_accessed() against an uninitialised pointer]
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Tested-by: default avatarPrabhakar Lad <prabhakar.csengg@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2457aec6
    • Mel Gorman's avatar
      fs: buffer: do not use unnecessary atomic operations when discarding buffers · e7470ee8
      Mel Gorman authored
      Discarding buffers uses a bunch of atomic operations when discarding
      buffers because ......  I can't think of a reason.  Use a cmpxchg loop to
      clear all the necessary flags.  In most (all?) cases this will be a single
      atomic operations.
      
      [akpm@linux-foundation.org: move BUFFER_FLAGS_DISCARD into the .c file]
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e7470ee8
    • Mel Gorman's avatar
      mm: do not use unnecessary atomic operations when adding pages to the LRU · 6fb81a17
      Mel Gorman authored
      When adding pages to the LRU we clear the active bit unconditionally.
      As the page could be reachable from other paths we cannot use unlocked
      operations without risk of corruption such as a parallel
      mark_page_accessed.  This patch tests if is necessary to clear the
      active flag before using an atomic operation.  This potentially opens a
      tiny race when PageActive is checked as mark_page_accessed could be
      called after PageActive was checked.  The race already exists but this
      patch changes it slightly.  The consequence is that that the page may be
      promoted to the active list that might have been left on the inactive
      list before the patch.  It's too tiny a race and too marginal a
      consequence to always use atomic operations for.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6fb81a17
    • Mel Gorman's avatar
      mm: do not use atomic operations when releasing pages · e3741b50
      Mel Gorman authored
      There should be no references to it any more and a parallel mark should
      not be reordered against us.  Use non-locked varient to clear page active.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e3741b50
    • Mel Gorman's avatar
      mm: shmem: avoid atomic operation during shmem_getpage_gfp · 07a42788
      Mel Gorman authored
      shmem_getpage_gfp uses an atomic operation to set the SwapBacked field
      before it's even added to the LRU or visible.  This is unnecessary as what
      could it possible race against?  Use an unlocked variant.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      07a42788
    • Mel Gorman's avatar
      mm: page_alloc: convert hot/cold parameter and immediate callers to bool · b745bc85
      Mel Gorman authored
      cold is a bool, make it one.  Make the likely case the "if" part of the
      block instead of the else as according to the optimisation manual this is
      preferred.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b745bc85
    • Mel Gorman's avatar
      mm: page_alloc: use unsigned int for order in more places · 7aeb09f9
      Mel Gorman authored
      X86 prefers the use of unsigned types for iterators and there is a
      tendency to mix whether a signed or unsigned type if used for page order.
      This converts a number of sites in mm/page_alloc.c to use unsigned int for
      order where possible.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7aeb09f9
    • Mel Gorman's avatar
      mm: page_alloc: lookup pageblock migratetype with IRQs enabled during free · cfc47a28
      Mel Gorman authored
      get_pageblock_migratetype() is called during free with IRQs disabled.
      This is unnecessary and disables IRQs for longer than necessary.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      cfc47a28
    • Mel Gorman's avatar
      mm: page_alloc: reduce number of times page_to_pfn is called · dc4b0caf
      Mel Gorman authored
      In the free path we calculate page_to_pfn multiple times. Reduce that.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      dc4b0caf
    • Mel Gorman's avatar
      mm: page_alloc: use word-based accesses for get/set pageblock bitmaps · e58469ba
      Mel Gorman authored
      The test_bit operations in get/set pageblock flags are expensive.  This
      patch reads the bitmap on a word basis and use shifts and masks to isolate
      the bits of interest.  Similarly masks are used to set a local copy of the
      bitmap and then use cmpxchg to update the bitmap if there have been no
      other changes made in parallel.
      
      In a test running dd onto tmpfs the overhead of the pageblock-related
      functions went from 1.27% in profiles to 0.5%.
      
      In addition to the performance benefits, this patch closes races that are
      possible between:
      
      a) get_ and set_pageblock_migratetype(), where get_pageblock_migratetype()
         reads part of the bits before and other part of the bits after
         set_pageblock_migratetype() has updated them.
      
      b) set_pageblock_migratetype() and set_pageblock_skip(), where the non-atomic
         read-modify-update set bit operation in set_pageblock_skip() will cause
         lost updates to some bits changed in the set_pageblock_migratetype().
      
      Joonsoo Kim first reported the case a) via code inspection.  Vlastimil
      Babka's testing with a debug patch showed that either a) or b) occurs
      roughly once per mmtests' stress-highalloc benchmark (although not
      necessarily in the same pageblock).  Furthermore during development of
      unrelated compaction patches, it was observed that frequent calls to
      {start,undo}_isolate_page_range() the race occurs several thousands of
      times and has resulted in NULL pointer dereferences in move_freepages()
      and free_one_page() in places where free_list[migratetype] is
      manipulated by e.g.  list_move().  Further debugging confirmed that
      migratetype had invalid value of 6, causing out of bounds access to the
      free_list array.
      
      That confirmed that the race exist, although it may be extremely rare,
      and currently only fatal where page isolation is performed due to
      memory hot remove.  Races on pageblocks being updated by
      set_pageblock_migratetype(), where both old and new migratetype are
      lower MIGRATE_RESERVE, currently cannot result in an invalid value
      being observed, although theoretically they may still lead to
      unexpected creation or destruction of MIGRATE_RESERVE pageblocks.
      Furthermore, things could get suddenly worse when memory isolation is
      used more, or when new migratetypes are added.
      
      After this patch, the race has no longer been observed in testing.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Reported-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Reported-and-tested-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.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>
      e58469ba
    • Mel Gorman's avatar
      mm: page_alloc: take the ALLOC_NO_WATERMARK check out of the fast path · 5dab2911
      Mel Gorman authored
      ALLOC_NO_WATERMARK is set in a few cases.  Always by kswapd, always for
      __GFP_MEMALLOC, sometimes for swap-over-nfs, tasks etc.  Each of these
      cases are relatively rare events but the ALLOC_NO_WATERMARK check is an
      unlikely branch in the fast path.  This patch moves the check out of the
      fast path and after it has been determined that the watermarks have not
      been met.  This helps the common fast path at the cost of making the slow
      path slower and hitting kswapd with a performance cost.  It's a reasonable
      tradeoff.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5dab2911
    • Mel Gorman's avatar
      mm: page_alloc: only check the alloc flags and gfp_mask for dirty once · a6e21b14
      Mel Gorman authored
      Currently it's calculated once per zone in the zonelist.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a6e21b14
    • Mel Gorman's avatar
      mm: page_alloc: only check the zone id check if pages are buddies · d34c5fa0
      Mel Gorman authored
      A node/zone index is used to check if pages are compatible for merging
      but this happens unconditionally even if the buddy page is not free. Defer
      the calculation as long as possible. Ideally we would check the zone boundary
      but nodes can overlap.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d34c5fa0
    • Mel Gorman's avatar
      mm: page_alloc: use jump labels to avoid checking number_of_cpusets · 664eedde
      Mel Gorman authored
      If cpusets are not in use then we still check a global variable on every
      page allocation.  Use jump labels to avoid the overhead.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      664eedde
    • Mel Gorman's avatar
      include/linux/jump_label.h: expose the reference count · ea5e9539
      Mel Gorman authored
      This patch exposes the jump_label reference count in preparation for the
      next patch.  cpusets cares about both the jump_label being enabled and how
      many users of the cpusets there currently are.
      Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Oleg Nesterov <oleg@redhat.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>
      ea5e9539
    • Mel Gorman's avatar
      mm: page_alloc: do not treat a zone that cannot be used for dirty pages as "full" · 800a1e75
      Mel Gorman authored
      If a zone cannot be used for a dirty page then it gets marked "full" which
      is cached in the zlc and later potentially skipped by allocation requests
      that have nothing to do with dirty zones.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarRik 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>
      800a1e75
    • Mel Gorman's avatar
      mm: page_alloc: do not update zlc unless the zlc is active · 65bb3719
      Mel Gorman authored
      The zlc is used on NUMA machines to quickly skip over zones that are full.
       However it is always updated, even for the first zone scanned when the
      zlc might not even be active.  As it's a write to a bitmap that
      potentially bounces cache line it's deceptively expensive and most
      machines will not care.  Only update the zlc if it was active.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarRik 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>
      65bb3719
    • Vladimir Davydov's avatar
      slab: delete cache from list after __kmem_cache_shutdown succeeds · 0bd62b11
      Vladimir Davydov authored
      Currently, on kmem_cache_destroy we delete the cache from the slab_list
      before __kmem_cache_shutdown, inserting it back to the list on failure.
      Initially, this was done, because we could release the slab_mutex in
      __kmem_cache_shutdown to delete sysfs slub entry, but since commit
      41a21285 ("slub: use sysfs'es release mechanism for kmem_cache") we
      remove sysfs entry later in kmem_cache_destroy after dropping the
      slab_mutex, so that no implementation of __kmem_cache_shutdown can ever
      release the lock.  Therefore we can simplify the code a bit by moving
      list_del after __kmem_cache_shutdown.
      Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: Pekka Enberg <penberg@kernel.org>
      Acked-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>
      0bd62b11
    • Vladimir Davydov's avatar
      memcg: cleanup kmem cache creation/destruction functions naming · 776ed0f0
      Vladimir Davydov authored
      Current names are rather inconsistent. Let's try to improve them.
      
      Brief change log:
      
      ** old name **                          ** new name **
      
      kmem_cache_create_memcg                 memcg_create_kmem_cache
      memcg_kmem_create_cache                 memcg_regsiter_cache
      memcg_kmem_destroy_cache                memcg_unregister_cache
      
      kmem_cache_destroy_memcg_children       memcg_cleanup_cache_params
      mem_cgroup_destroy_all_caches           memcg_unregister_all_caches
      
      create_work                             memcg_register_cache_work
      memcg_create_cache_work_func            memcg_register_cache_func
      memcg_create_cache_enqueue              memcg_schedule_register_cache
      Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      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>
      776ed0f0
    • Andy Shevchenko's avatar
      mm/dmapool.c: reuse devres_release() to free resources · 172cb4b3
      Andy Shevchenko authored
      Instead of calling an additional routine in dmam_pool_destroy() rely on
      what dmam_pool_release() is doing.
      Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      172cb4b3
    • Marc Carino's avatar
      cma: increase CMA_ALIGNMENT upper limit to 12 · fe54b1fd
      Marc Carino authored
      Some systems require a larger maximum PAGE_SIZE order for CMA allocations.
       To accommodate such systems, increase the upper-bound of the
      CMA_ALIGNMENT range to 12 (which ends up being 16MB on systems with 4K
      pages).
      Signed-off-by: default avatarMarc Carino <marc.ceeeee@gmail.com>
      Cc: Marek Szyprowski <m.szyprowski@samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fe54b1fd
    • Dan Streetman's avatar
      swap: change swap_list_head to plist, add swap_avail_head · 18ab4d4c
      Dan Streetman authored
      Originally get_swap_page() started iterating through the singly-linked
      list of swap_info_structs using swap_list.next or highest_priority_index,
      which both were intended to point to the highest priority active swap
      target that was not full.  The first patch in this series changed the
      singly-linked list to a doubly-linked list, and removed the logic to start
      at the highest priority non-full entry; it starts scanning at the highest
      priority entry each time, even if the entry is full.
      
      Replace the manually ordered swap_list_head with a plist, swap_active_head.
      Add a new plist, swap_avail_head.  The original swap_active_head plist
      contains all active swap_info_structs, as before, while the new
      swap_avail_head plist contains only swap_info_structs that are active and
      available, i.e. not full.  Add a new spinlock, swap_avail_lock, to protect
      the swap_avail_head list.
      
      Mel Gorman suggested using plists since they internally handle ordering
      the list entries based on priority, which is exactly what swap was doing
      manually.  All the ordering code is now removed, and swap_info_struct
      entries and simply added to their corresponding plist and automatically
      ordered correctly.
      
      Using a new plist for available swap_info_structs simplifies and
      optimizes get_swap_page(), which no longer has to iterate over full
      swap_info_structs.  Using a new spinlock for swap_avail_head plist
      allows each swap_info_struct to add or remove themselves from the
      plist when they become full or not-full; previously they could not
      do so because the swap_info_struct->lock is held when they change
      from full<->not-full, and the swap_lock protecting the main
      swap_active_head must be ordered before any swap_info_struct->lock.
      Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Shaohua Li <shli@fusionio.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dan Streetman <ddstreet@ieee.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
      Cc: Weijie Yang <weijieut@gmail.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Bob Liu <bob.liu@oracle.com>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      18ab4d4c
    • Dan Streetman's avatar
      lib/plist: add plist_requeue · a75f232c
      Dan Streetman authored
      Add plist_requeue(), which moves the specified plist_node after all other
      same-priority plist_nodes in the list.  This is essentially an optimized
      plist_del() followed by plist_add().
      
      This is needed by swap, which (with the next patch in this set) uses a
      plist of available swap devices.  When a swap device (either a swap
      partition or swap file) are added to the system with swapon(), the device
      is added to a plist, ordered by the swap device's priority.  When swap
      needs to allocate a page from one of the swap devices, it takes the page
      from the first swap device on the plist, which is the highest priority
      swap device.  The swap device is left in the plist until all its pages are
      used, and then removed from the plist when it becomes full.
      
      However, as described in man 2 swapon, swap must allocate pages from swap
      devices with the same priority in round-robin order; to do this, on each
      swap page allocation, swap uses a page from the first swap device in the
      plist, and then calls plist_requeue() to move that swap device entry to
      after any other same-priority swap devices.  The next swap page allocation
      will again use a page from the first swap device in the plist and requeue
      it, and so on, resulting in round-robin usage of equal-priority swap
      devices.
      
      Also add plist_test_requeue() test function, for use by plist_test() to
      test plist_requeue() function.
      Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Shaohua Li <shli@fusionio.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dan Streetman <ddstreet@ieee.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
      Cc: Weijie Yang <weijieut@gmail.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Bob Liu <bob.liu@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a75f232c
    • Dan Streetman's avatar
      lib/plist: add helper functions · fd16618e
      Dan Streetman authored
      Add PLIST_HEAD() to plist.h, equivalent to LIST_HEAD() from list.h, to
      define and initialize a struct plist_head.
      
      Add plist_for_each_continue() and plist_for_each_entry_continue(),
      equivalent to list_for_each_continue() and list_for_each_entry_continue(),
      to iterate over a plist continuing after the current position.
      
      Add plist_prev() and plist_next(), equivalent to (struct list_head*)->prev
      and ->next, implemented by list_prev_entry() and list_next_entry(), to
      access the prev/next struct plist_node entry.  These are needed because
      unlike struct list_head, direct access of the prev/next struct plist_node
      isn't possible; the list must be navigated via the contained struct
      list_head.  e.g.  instead of accessing the prev by list_prev_entry(node,
      node_list) it can be accessed by plist_prev(node).
      Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Shaohua Li <shli@fusionio.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dan Streetman <ddstreet@ieee.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
      Cc: Weijie Yang <weijieut@gmail.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Bob Liu <bob.liu@oracle.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fd16618e
    • Dan Streetman's avatar
      swap: change swap_info singly-linked list to list_head · adfab836
      Dan Streetman authored
      The logic controlling the singly-linked list of swap_info_struct entries
      for all active, i.e.  swapon'ed, swap targets is rather complex, because:
      
       - it stores the entries in priority order
       - there is a pointer to the highest priority entry
       - there is a pointer to the highest priority not-full entry
       - there is a highest_priority_index variable set outside the swap_lock
       - swap entries of equal priority should be used equally
      
      this complexity leads to bugs such as: https://lkml.org/lkml/2014/2/13/181
      where different priority swap targets are incorrectly used equally.
      
      That bug probably could be solved with the existing singly-linked lists,
      but I think it would only add more complexity to the already difficult to
      understand get_swap_page() swap_list iteration logic.
      
      The first patch changes from a singly-linked list to a doubly-linked list
      using list_heads; the highest_priority_index and related code are removed
      and get_swap_page() starts each iteration at the highest priority
      swap_info entry, even if it's full.  While this does introduce unnecessary
      list iteration (i.e.  Schlemiel the painter's algorithm) in the case where
      one or more of the highest priority entries are full, the iteration and
      manipulation code is much simpler and behaves correctly re: the above bug;
      and the fourth patch removes the unnecessary iteration.
      
      The second patch adds some minor plist helper functions; nothing new
      really, just functions to match existing regular list functions.  These
      are used by the next two patches.
      
      The third patch adds plist_requeue(), which is used by get_swap_page() in
      the next patch - it performs the requeueing of same-priority entries
      (which moves the entry to the end of its priority in the plist), so that
      all equal-priority swap_info_structs get used equally.
      
      The fourth patch converts the main list into a plist, and adds a new plist
      that contains only swap_info entries that are both active and not full.
      As Mel suggested using plists allows removing all the ordering code from
      swap - plists handle ordering automatically.  The list naming is also
      clarified now that there are two lists, with the original list changed
      from swap_list_head to swap_active_head and the new list named
      swap_avail_head.  A new spinlock is also added for the new list, so
      swap_info entries can be added or removed from the new list immediately as
      they become full or not full.
      
      This patch (of 4):
      
      Replace the singly-linked list tracking active, i.e.  swapon'ed,
      swap_info_struct entries with a doubly-linked list using struct
      list_heads.  Simplify the logic iterating and manipulating the list of
      entries, especially get_swap_page(), by using standard list_head
      functions, and removing the highest priority iteration logic.
      
      The change fixes the bug:
      https://lkml.org/lkml/2014/2/13/181
      in which different priority swap entries after the highest priority entry
      are incorrectly used equally in pairs.  The swap behavior is now as
      advertised, i.e. different priority swap entries are used in order, and
      equal priority swap targets are used concurrently.
      Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Shaohua Li <shli@fusionio.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Dan Streetman <ddstreet@ieee.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
      Cc: Weijie Yang <weijieut@gmail.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Bob Liu <bob.liu@oracle.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      adfab836
    • Jianyu Zhan's avatar
      mm: fold mlocked_vma_newpage() into its only call site · 7ee07a44
      Jianyu Zhan authored
      In previous commit(mm: use the light version __mod_zone_page_state in
      mlocked_vma_newpage()) a irq-unsafe __mod_zone_page_state is used.  And as
      suggested by Andrew, to reduce the risks that new call sites incorrectly
      using mlocked_vma_newpage() without knowing they are adding racing, this
      patch folds mlocked_vma_newpage() into its only call site,
      page_add_new_anon_rmap, to make it open-cocded for people to know what is
      going on.
      
      [akpm@linux-foundation.org: coding-style fixes]
      Signed-off-by: default avatarJianyu Zhan <nasa4836@gmail.com>
      Suggested-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Suggested-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarHugh Dickins <hughd@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7ee07a44
    • Jianyu Zhan's avatar
      mm: use the light version __mod_zone_page_state in mlocked_vma_newpage() · bea04b07
      Jianyu Zhan authored
      mlocked_vma_newpage() is called with pte lock held(a spinlock), which
      implies preemtion disabled, and the vm stat counter is not modified from
      interrupt context, so we need not use an irq-safe mod_zone_page_state()
      here, using a light-weight version __mod_zone_page_state() would be OK.
      
      This patch also documents __mod_zone_page_state() and some of its
      callsites.  The comment above __mod_zone_page_state() is from Hugh
      Dickins, and acked by Christoph.
      
      Most credits to Hugh and Christoph for the clarification on the usage of
      the __mod_zone_page_state().
      
      [akpm@linux-foundation.org: coding-style fixes]
      Suggested-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Acked-by: default avatarHugh Dickins <hughd@google.com>
      Signed-off-by: default avatarJianyu Zhan <nasa4836@gmail.com>
      Reviewed-by: default avatarChristoph Lameter <cl@linux.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bea04b07
    • Vlastimil Babka's avatar
      mm/compaction: avoid rescanning pageblocks in isolate_freepages · e9ade569
      Vlastimil Babka authored
      The compaction free scanner in isolate_freepages() currently remembers PFN
      of the highest pageblock where it successfully isolates, to be used as the
      starting pageblock for the next invocation.  The rationale behind this is
      that page migration might return free pages to the allocator when
      migration fails and we don't want to skip them if the compaction
      continues.
      
      Since migration now returns free pages back to compaction code where they
      can be reused, this is no longer a concern.  This patch changes
      isolate_freepages() so that the PFN for restarting is updated with each
      pageblock where isolation is attempted.  Using stress-highalloc from
      mmtests, this resulted in 10% reduction of the pages scanned by the free
      scanner.
      
      Note that the somewhat similar functionality that records highest
      successful pageblock in zone->compact_cached_free_pfn, remains unchanged.
      This cache is used when the whole compaction is restarted, not for
      multiple invocations of the free scanner during single compaction.
      Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
      Acked-by: default avatarMichal Nazarewicz <mina86@mina86.com>
      Reviewed-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: Rik van Riel <riel@redhat.com>
      Acked-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>
      e9ade569
    • Vlastimil Babka's avatar
      mm/compaction: do not count migratepages when unnecessary · f8c9301f
      Vlastimil Babka authored
      During compaction, update_nr_listpages() has been used to count remaining
      non-migrated and free pages after a call to migrage_pages().  The
      freepages counting has become unneccessary, and it turns out that
      migratepages counting is also unnecessary in most cases.
      
      The only situation when it's needed to count cc->migratepages is when
      migrate_pages() returns with a negative error code.  Otherwise, the
      non-negative return value is the number of pages that were not migrated,
      which is exactly the count of remaining pages in the cc->migratepages
      list.
      
      Furthermore, any non-zero count is only interesting for the tracepoint of
      mm_compaction_migratepages events, because after that all remaining
      unmigrated pages are put back and their count is set to 0.
      
      This patch therefore removes update_nr_listpages() completely, and changes
      the tracepoint definition so that the manual counting is done only when
      the tracepoint is enabled, and only when migrate_pages() returns a
      negative error code.
      
      Furthermore, migrate_pages() and the tracepoints won't be called when
      there's nothing to migrate.  This potentially avoids some wasted cycles
      and reduces the volume of uninteresting mm_compaction_migratepages events
      where "nr_migrated=0 nr_failed=0".  In the stress-highalloc mmtest, this
      was about 75% of the events.  The mm_compaction_isolate_migratepages event
      is better for determining that nothing was isolated for migration, and
      this one was just duplicating the info.
      Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Reviewed-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
      Acked-by: default avatarMichal Nazarewicz <mina86@mina86.com>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: Rik van Riel <riel@redhat.com>
      Acked-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>
      f8c9301f
    • David Rientjes's avatar
      mm, compaction: terminate async compaction when rescheduling · aeef4b83
      David Rientjes authored
      Async compaction terminates prematurely when need_resched(), see
      compact_checklock_irqsave().  This can never trigger, however, if the
      cond_resched() in isolate_migratepages_range() always takes care of the
      scheduling.
      
      If the cond_resched() actually triggers, then terminate this pageblock
      scan for async compaction as well.
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      aeef4b83
    • David Rientjes's avatar
      mm, thp: avoid excessive compaction latency during fault · 75f30861
      David Rientjes authored
      Synchronous memory compaction can be very expensive: it can iterate an
      enormous amount of memory without aborting, constantly rescheduling,
      waiting on page locks and lru_lock, etc, if a pageblock cannot be
      defragmented.
      
      Unfortunately, it's too expensive for transparent hugepage page faults and
      it's much better to simply fallback to pages.  On 128GB machines, we find
      that synchronous memory compaction can take O(seconds) for a single thp
      fault.
      
      Now that async compaction remembers where it left off without strictly
      relying on sync compaction, this makes thp allocations best-effort without
      causing egregious latency during fault.  We still need to retry async
      compaction after reclaim, but this won't stall for seconds.
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Hugh Dickins <hughd@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      75f30861
    • David Rientjes's avatar
      mm, compaction: embed migration mode in compact_control · e0b9daeb
      David Rientjes authored
      We're going to want to manipulate the migration mode for compaction in the
      page allocator, and currently compact_control's sync field is only a bool.
      
      Currently, we only do MIGRATE_ASYNC or MIGRATE_SYNC_LIGHT compaction
      depending on the value of this bool.  Convert the bool to enum
      migrate_mode and pass the migration mode in directly.  Later, we'll want
      to avoid MIGRATE_SYNC_LIGHT for thp allocations in the pagefault patch to
      avoid unnecessary latency.
      
      This also alters compaction triggered from sysfs, either for the entire
      system or for a node, to force MIGRATE_SYNC.
      
      [akpm@linux-foundation.org: fix build]
      [iamjoonsoo.kim@lge.com: use MIGRATE_SYNC in alloc_contig_range()]
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Suggested-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e0b9daeb
    • David Rientjes's avatar
      mm, compaction: add per-zone migration pfn cache for async compaction · 35979ef3
      David Rientjes authored
      Each zone has a cached migration scanner pfn for memory compaction so that
      subsequent calls to memory compaction can start where the previous call
      left off.
      
      Currently, the compaction migration scanner only updates the per-zone
      cached pfn when pageblocks were not skipped for async compaction.  This
      creates a dependency on calling sync compaction to avoid having subsequent
      calls to async compaction from scanning an enormous amount of non-MOVABLE
      pageblocks each time it is called.  On large machines, this could be
      potentially very expensive.
      
      This patch adds a per-zone cached migration scanner pfn only for async
      compaction.  It is updated everytime a pageblock has been scanned in its
      entirety and when no pages from it were successfully isolated.  The cached
      migration scanner pfn for sync compaction is updated only when called for
      sync compaction.
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Reviewed-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      35979ef3
    • David Rientjes's avatar
      mm, compaction: return failed migration target pages back to freelist · d53aea3d
      David Rientjes authored
      Greg reported that he found isolated free pages were returned back to the
      VM rather than the compaction freelist.  This will cause holes behind the
      free scanner and cause it to reallocate additional memory if necessary
      later.
      
      He detected the problem at runtime seeing that ext4 metadata pages (esp
      the ones read by "sbi->s_group_desc[i] = sb_bread(sb, block)") were
      constantly visited by compaction calls of migrate_pages().  These pages
      had a non-zero b_count which caused fallback_migrate_page() ->
      try_to_release_page() -> try_to_free_buffers() to fail.
      
      Memory compaction works by having a "freeing scanner" scan from one end of
      a zone which isolates pages as migration targets while another "migrating
      scanner" scans from the other end of the same zone which isolates pages
      for migration.
      
      When page migration fails for an isolated page, the target page is
      returned to the system rather than the freelist built by the freeing
      scanner.  This may require the freeing scanner to continue scanning memory
      after suitable migration targets have already been returned to the system
      needlessly.
      
      This patch returns destination pages to the freeing scanner freelist when
      page migration fails.  This prevents unnecessary work done by the freeing
      scanner but also encourages memory to be as compacted as possible at the
      end of the zone.
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Reported-by: default avatarGreg Thelen <gthelen@google.com>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Reviewed-by: default avatarNaoya 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>
      d53aea3d
    • David Rientjes's avatar
      mm, migration: add destination page freeing callback · 68711a74
      David Rientjes authored
      Memory migration uses a callback defined by the caller to determine how to
      allocate destination pages.  When migration fails for a source page,
      however, it frees the destination page back to the system.
      
      This patch adds a memory migration callback defined by the caller to
      determine how to free destination pages.  If a caller, such as memory
      compaction, builds its own freelist for migration targets, this can reuse
      already freed memory instead of scanning additional memory.
      
      If the caller provides a function to handle freeing of destination pages,
      it is called when page migration fails.  If the caller passes NULL then
      freeing back to the system will be handled as usual.  This patch
      introduces no functional change.
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Reviewed-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Cc: Greg Thelen <gthelen@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      68711a74
    • Vladimir Davydov's avatar
      memcg: memcg_kmem_create_cache: make memcg_name_buf statically allocated · 93f39eea
      Vladimir Davydov authored
      It isn't worth complicating the code by allocating it on the first access,
      because it only takes 256 bytes.
      Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
      Cc: Michal Hocko <mhocko@suse.cz>
      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>
      93f39eea
    • Vladimir Davydov's avatar
      memcg: get rid of memcg_create_cache_name · 073ee1c6
      Vladimir Davydov authored
      Instead of calling back to memcontrol.c from kmem_cache_create_memcg in
      order to just create the name of a per memcg cache, let's allocate it in
      place.  We only need to pass the memcg name to kmem_cache_create_memcg for
      that - everything else can be done in slab_common.c.
      Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      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>
      073ee1c6
    • Qiang Huang's avatar
      memcg: correct comments for __mem_cgroup_begin_update_page_stat · b5ffc856
      Qiang Huang authored
      Signed-off-by: default avatarQiang Huang <h.huangqiang@huawei.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      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>
      b5ffc856