1. 02 Aug, 2012 33 commits
    • Hans de Goede's avatar
      usbdevfs: Correct amount of data copied to user in processcompl_compat · 6d051149
      Hans de Goede authored
      commit 2102e06a upstream.
      
      iso data buffers may have holes in them if some packets were short, so for
      iso urbs we should always copy the entire buffer, just like the regular
      processcompl does.
      Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
      Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      6d051149
    • Borislav Petkov's avatar
      x86, microcode: Sanitize per-cpu microcode reloading interface · 87b98a1d
      Borislav Petkov authored
      commit c9fc3f77 upstream.
      
      Microcode reloading in a per-core manner is a very bad idea for both
      major x86 vendors. And the thing is, we have such interface with which
      we can end up with different microcode versions applied on different
      cores of an otherwise homogeneous wrt (family,model,stepping) system.
      
      So turn off the possibility of doing that per core and allow it only
      system-wide.
      
      This is a minimal fix which we'd like to see in stable too thus the
      more-or-less arbitrary decision to allow system-wide reloading only on
      the BSP:
      
      $ echo 1 > /sys/devices/system/cpu/cpu0/microcode/reload
      ...
      
      and disable the interface on the other cores:
      
      $ echo 1 > /sys/devices/system/cpu/cpu23/microcode/reload
      -bash: echo: write error: Invalid argument
      
      Also, allowing the reload only from one CPU (the BSP in
      that case) doesn't allow the reload procedure to degenerate
      into an O(n^2) deal when triggering reloads from all
      /sys/devices/system/cpu/cpuX/microcode/reload sysfs nodes
      simultaneously.
      
      A more generic fix will follow.
      
      Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarBorislav Petkov <borislav.petkov@amd.com>
      Link: http://lkml.kernel.org/r/1340280437-7718-2-git-send-email-bp@amd64.orgSigned-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      87b98a1d
    • Shuah Khan's avatar
      x86, microcode: microcode_core.c simple_strtoul cleanup · f7b867b5
      Shuah Khan authored
      commit e826abd5 upstream.
      
      Change reload_for_cpu() in kernel/microcode_core.c to call kstrtoul()
      instead of calling obsoleted simple_strtoul().
      Signed-off-by: default avatarShuah Khan <shuahkhan@gmail.com>
      Reviewed-by: default avatarBorislav Petkov <bp@alien8.de>
      Link: http://lkml.kernel.org/r/1336324264.2897.9.camel@lorien2Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      f7b867b5
    • Srivatsa S. Bhat's avatar
      ftrace: Disable function tracing during suspend/resume and hibernation, again · 701aa114
      Srivatsa S. Bhat authored
      commit 443772d4 upstream.
      
      If function tracing is enabled for some of the low-level suspend/resume
      functions, it leads to triple fault during resume from suspend, ultimately
      ending up in a reboot instead of a resume (or a total refusal to come out
      of suspended state, on some machines).
      
      This issue was explained in more detail in commit f42ac38c (ftrace:
      disable tracing for suspend to ram). However, the changes made by that commit
      got reverted by commit cbe2f5a6 (tracing: allow tracing of
      suspend/resume & hibernation code again). So, unfortunately since things are
      not yet robust enough to allow tracing of low-level suspend/resume functions,
      suspend/resume is still broken when ftrace is enabled.
      
      So fix this by disabling function tracing during suspend/resume & hibernation.
      Signed-off-by: default avatarSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      701aa114
    • Theodore Ts'o's avatar
      ext4: pass a char * to ext4_count_free() instead of a buffer_head ptr · 2a129c73
      Theodore Ts'o authored
      commit f6fb99ca upstream.
      
      Make it possible for ext4_count_free to operate on buffers and not
      just data in buffer_heads.
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      [bwh: Backported to 3.2: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      2a129c73
    • Kevin Cernekee's avatar
      usb: gadget: Fix g_ether interface link status · 0331c3a6
      Kevin Cernekee authored
      commit 31bde1ce upstream.
      
      A "usb0" interface that has never been connected to a host has an unknown
      operstate, and therefore the IFF_RUNNING flag is (incorrectly) asserted
      when queried by ifconfig, ifplugd, etc.  This is a result of calling
      netif_carrier_off() too early in the probe function; it should be called
      after register_netdev().
      
      Similar problems have been fixed in many other drivers, e.g.:
      
          e826eafa (bonding: Call netif_carrier_off after register_netdevice)
          0d672e9f (drivers/net: Call netif_carrier_off at the end of the probe)
          6a3c869a (cxgb4: fix reported state of interfaces without link)
      
      Fix is to move netif_carrier_off() to the end of the function.
      Signed-off-by: default avatarKevin Cernekee <cernekee@gmail.com>
      Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      0331c3a6
    • Albert Pool's avatar
      rt2800usb: 2001:3c17 is an RT3370 device · 8d54ec42
      Albert Pool authored
      commit 8fd9d059 upstream.
      
      D-Link DWA-123 rev A1
      
      Signed-off-by: Albert Pool<albertpool@solcon.nl>
      Acked-by: default avatarGertjan van Wingerde <gwingerde@gmail.com>
      Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      8d54ec42
    • Xose Vazquez Perez's avatar
      wireless: rt2x00: rt2800usb more devices were identified · cd7100a8
      Xose Vazquez Perez authored
      commit e828b9fb upstream.
      
      found in 2012_03_22_RT5572_Linux_STA_v2.6.0.0_DPO
      
      RT3070:
      (0x2019,0x5201)  Planex Communications, Inc. RT8070
      (0x7392,0x4085)  2L Central Europe BV 8070
      7392 is Edimax
      
      RT35xx:
      (0x1690,0x0761) Askey
      was Fujitsu Stylistic 550, but 1690 is Askey
      Signed-off-by: default avatarXose Vazquez Perez <xose.vazquez@gmail.com>
      Acked-by: default avatarGertjan van Wingerde <gwingerde@gmail.com>
      Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      cd7100a8
    • Xose Vazquez Perez's avatar
      wireless: rt2x00: rt2800usb add more devices ids · 0fd47a3f
      Xose Vazquez Perez authored
      commit 63b37641 upstream.
      
      They were taken from ralink drivers:
      2011_0719_RT3070_RT3370_RT5370_RT5372_Linux_STA_V2.5.0.3_DPO
      2012_03_22_RT5572_Linux_STA_v2.6.0.0_DPO
      
      0x1eda,0x2210 RT3070 Airties
      
      0x083a,0xb511 RT3370 Panasonic
      0x0471,0x20dd RT3370 Philips
      
      0x1690,0x0764 RT35xx Askey
      0x0df6,0x0065 RT35xx Sitecom
      0x0df6,0x0066 RT35xx Sitecom
      0x0df6,0x0068 RT35xx Sitecom
      
      0x2001,0x3c1c RT5370 DLink
      0x2001,0x3c1d RT5370 DLink
      
      2001 is D-Link not Alpha
      Signed-off-by: default avatarXose Vazquez Perez <xose.vazquez@gmail.com>
      Acked-by: default avatarGertjan van Wingerde <gwingerde@gmail.com>
      Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
      [bwh: Backported to 3.2: drop the 5372 devices]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      0fd47a3f
    • Jeff Layton's avatar
      cifs: when CONFIG_HIGHMEM is set, serialize the read/write kmaps · bb761c98
      Jeff Layton authored
      commit 3cf003c0 upstream.
      
      Jian found that when he ran fsx on a 32 bit arch with a large wsize the
      process and one of the bdi writeback kthreads would sometimes deadlock
      with a stack trace like this:
      
      crash> bt
      PID: 2789   TASK: f02edaa0  CPU: 3   COMMAND: "fsx"
       #0 [eed63cbc] schedule at c083c5b3
       #1 [eed63d80] kmap_high at c0500ec8
       #2 [eed63db0] cifs_async_writev at f7fabcd7 [cifs]
       #3 [eed63df0] cifs_writepages at f7fb7f5c [cifs]
       #4 [eed63e50] do_writepages at c04f3e32
       #5 [eed63e54] __filemap_fdatawrite_range at c04e152a
       #6 [eed63ea4] filemap_fdatawrite at c04e1b3e
       #7 [eed63eb4] cifs_file_aio_write at f7fa111a [cifs]
       #8 [eed63ecc] do_sync_write at c052d202
       #9 [eed63f74] vfs_write at c052d4ee
      #10 [eed63f94] sys_write at c052df4c
      #11 [eed63fb0] ia32_sysenter_target at c0409a98
          EAX: 00000004  EBX: 00000003  ECX: abd73b73  EDX: 012a65c6
          DS:  007b      ESI: 012a65c6  ES:  007b      EDI: 00000000
          SS:  007b      ESP: bf8db178  EBP: bf8db1f8  GS:  0033
          CS:  0073      EIP: 40000424  ERR: 00000004  EFLAGS: 00000246
      
      Each task would kmap part of its address array before getting stuck, but
      not enough to actually issue the write.
      
      This patch fixes this by serializing the marshal_iov operations for
      async reads and writes. The idea here is to ensure that cifs
      aggressively tries to populate a request before attempting to fulfill
      another one. As soon as all of the pages are kmapped for a request, then
      we can unlock and allow another one to proceed.
      
      There's no need to do this serialization on non-CONFIG_HIGHMEM arches
      however, so optimize all of this out when CONFIG_HIGHMEM isn't set.
      Reported-by: default avatarJian Li <jiali@redhat.com>
      Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
      Signed-off-by: default avatarSteve French <smfrench@gmail.com>
      [bwh: Backported to 3.2: adjust context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      bb761c98
    • françois romieu's avatar
      r8169: RxConfig hack for the 8168evl. · e67de1a5
      françois romieu authored
      commit eb2dc35d upstream.
      
      The 8168evl (RTL_GIGA_MAC_VER_34) based Gigabyte GA-990FXA motherboards
      are very prone to NETDEV watchdog problems without this change. See
      https://bugzilla.kernel.org/show_bug.cgi?id=42899 for instance.
      
      I don't know why it *works*. It's depressingly effective though.
      
      For the record:
      - the problem may go along IOMMU (AMD-Vi) errors but it really looks
        like a red herring.
      - the patch sets the RX_MULTI_EN bit. If the 8168c doc is any guide,
        the chipset now fetches several Rx descriptors at a time.
      - long ago the driver ignored the RX_MULTI_EN bit.
        e542a226 changed the RxConfig
        settings. Whatever the problem it's now labeled a regression.
      - Realtek's own driver can identify two different 8168evl devices
        (CFG_METHOD_16 and CFG_METHOD_17) where the r8169 driver only
        sees one. It sucks.
      Signed-off-by: default avatarFrancois Romieu <romieu@fr.zoreil.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      e67de1a5
    • Alan Cox's avatar
      x86: Fix boot on Twinhead H12Y · 2c608967
      Alan Cox authored
      commit 80b3e557 upstream.
      
      Despite lots of investigation into why this is needed we don't
      know or have an elegant cure. The only answer found on this
      laptop is to mark a problem region as used so that Linux doesn't
      put anything there.
      
      Currently all the users add reserve= command lines and anyone
      not knowing this needs to find the magic page that documents it.
      Automate it instead.
      Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
      Tested-and-bugfixed-by: default avatarArne Fitzenreiter <arne@fitzenreiter.de>
      Resolves-bug: https://bugzilla.kernel.org/show_bug.cgi?id=10231
      Link: http://lkml.kernel.org/r/20120515174347.5109.94551.stgit@bluebookSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      2c608967
    • Ezequiel Garcia's avatar
      cx25821: Remove bad strcpy to read-only char* · 1b5b48b8
      Ezequiel Garcia authored
      commit 380e99fc upstream.
      
      The strcpy was being used to set the name of the board.  Since the
      destination char* was read-only and the name is set statically at
      compile time; this was both wrong and redundant.
      
      The type of char* is changed to const char* to prevent future errors.
      Reported-by: default avatarRadek Masin <radek@masin.eu>
      Signed-off-by: default avatarEzequiel Garcia <elezegarcia@gmail.com>
      [ Taking directly due to vacations   - Linus ]
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      1b5b48b8
    • roger blofeld's avatar
      powerpc/ftrace: Fix assembly trampoline register usage · 318ee754
      roger blofeld authored
      commit fd5a4298 upstream.
      
      Just like the module loader, ftrace needs to be updated to use r12
      instead of r11 with newer gcc's.
      Signed-off-by: default avatarRoger Blofeld <blofeldus@yahoo.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      318ee754
    • Peter Zijlstra's avatar
      sched/nohz: Fix rq->cpu_load calculations some more · c812fe63
      Peter Zijlstra authored
      commit 5aaa0b7a upstream.
      
      Follow up on commit 556061b0 ("sched/nohz: Fix rq->cpu_load[]
      calculations") since while that fixed the busy case it regressed the
      mostly idle case.
      
      Add a callback from the nohz exit to also age the rq->cpu_load[]
      array. This closes the hole where either there was no nohz load
      balance pass during the nohz, or there was a 'significant' amount of
      idle time between the last nohz balance and the nohz exit.
      
      So we'll update unconditionally from the tick to not insert any
      accidental 0 load periods while busy, and we try and catch up from
      nohz idle balance and nohz exit. Both these are still prone to missing
      a jiffy, but that has always been the case.
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: pjt@google.com
      Cc: Venkatesh Pallipadi <venki@google.com>
      Link: http://lkml.kernel.org/n/tip-kt0trz0apodbf84ucjfdbr1a@git.kernel.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      [bwh: Backported to 3.2: adjust filenames and context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      c812fe63
    • Peter Zijlstra's avatar
      sched/nohz: Fix rq->cpu_load[] calculations · 1217fd87
      Peter Zijlstra authored
      commit 556061b0 upstream.
      
      While investigating why the load-balancer did funny I found that the
      rq->cpu_load[] tables were completely screwy.. a bit more digging
      revealed that the updates that got through were missing ticks followed
      by a catchup of 2 ticks.
      
      The catchup assumes the cpu was idle during that time (since only nohz
      can cause missed ticks and the machine is idle etc..) this means that
      esp. the higher indices were significantly lower than they ought to
      be.
      
      The reason for this is that its not correct to compare against jiffies
      on every jiffy on any other cpu than the cpu that updates jiffies.
      
      This patch cludges around it by only doing the catch-up stuff from
      nohz_idle_balance() and doing the regular stuff unconditionally from
      the tick.
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: pjt@google.com
      Cc: Venkatesh Pallipadi <venki@google.com>
      Link: http://lkml.kernel.org/n/tip-tp4kj18xdd5aj4vvj0qg55s2@git.kernel.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      [bwh: Backported to 3.2: adjust filenames and context; keep functions static]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      1217fd87
    • Mark Rustad's avatar
      Fix NULL dereferences in scsi_cmd_to_driver · 2b2c3e47
      Mark Rustad authored
      commit 222a806a upstream.
      
      Avoid crashing if the private_data pointer happens to be NULL. This has
      been seen sometimes when a host reset happens, notably when there are
      many LUNs:
      
      host3: Assigned Port ID 0c1601
      scsi host3: libfc: Host reset succeeded on port (0c1601)
      BUG: unable to handle kernel NULL pointer dereference at 0000000000000350
      IP: [<ffffffff81352bb8>] scsi_send_eh_cmnd+0x58/0x3a0
      <snip>
      Process scsi_eh_3 (pid: 4144, threadinfo ffff88030920c000, task ffff880326b160c0)
      Stack:
       000000010372e6ba 0000000000000282 000027100920dca0 ffffffffa0038ee0
       0000000000000000 0000000000030003 ffff88030920dc80 ffff88030920dc80
       00000002000e0000 0000000a00004000 ffff8803242f7760 ffff88031326ed80
      Call Trace:
       [<ffffffff8105b590>] ? lock_timer_base+0x70/0x70
       [<ffffffff81352fbe>] scsi_eh_tur+0x3e/0xc0
       [<ffffffff81353a36>] scsi_eh_test_devices+0x76/0x170
       [<ffffffff81354125>] scsi_eh_host_reset+0x85/0x160
       [<ffffffff81354291>] scsi_eh_ready_devs+0x91/0x110
       [<ffffffff813543fd>] scsi_unjam_host+0xed/0x1f0
       [<ffffffff813546a8>] scsi_error_handler+0x1a8/0x200
       [<ffffffff81354500>] ? scsi_unjam_host+0x1f0/0x1f0
       [<ffffffff8106ec3e>] kthread+0x9e/0xb0
       [<ffffffff81509264>] kernel_thread_helper+0x4/0x10
       [<ffffffff8106eba0>] ? kthread_freezable_should_stop+0x70/0x70
       [<ffffffff81509260>] ? gs_change+0x13/0x13
      Code: 25 28 00 00 00 48 89 45 c8 31 c0 48 8b 87 80 00 00 00 48 8d b5 60 ff ff ff 89 d1 48 89 fb 41 89 d6 4c 89 fa 48 8b 80 b8 00 00 00
       <48> 8b 80 50 03 00 00 48 8b 00 48 89 85 38 ff ff ff 48 8b 07 4c
      RIP  [<ffffffff81352bb8>] scsi_send_eh_cmnd+0x58/0x3a0
       RSP <ffff88030920dc50>
      CR2: 0000000000000350
      Signed-off-by: default avatarMark Rustad <mark.d.rustad@intel.com>
      Tested-by: default avatarMarcus Dennis <marcusx.e.dennis@intel.com>
      Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
      [bwh: Backported to 3.2: adjust filename, context]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      2b2c3e47
    • Konstantin Khlebnikov's avatar
      mm/hugetlb: fix warning in alloc_huge_page/dequeue_huge_page_vma · e07e835a
      Konstantin Khlebnikov authored
      commit b1c12cbc upstream.
      
      Stable note: Not tracked in Bugzilla. [get|put]_mems_allowed() is extremely
      	expensive and severely impacted page allocator performance. This
      	is part of a series of patches that reduce page allocator overhead.
      
      Fix a gcc warning (and bug?) introduced in cc9a6c87 ("cpuset: mm: reduce
      large amounts of memory barrier related damage v3")
      
      Local variable "page" can be uninitialized if the nodemask from vma policy
      does not intersects with nodemask from cpuset.  Even if it doesn't happens
      it is better to initialize this variable explicitly than to introduce
      a kernel oops in a weird corner case.
      
      mm/hugetlb.c: In function `alloc_huge_page':
      mm/hugetlb.c:1135:5: warning: `page' may be used uninitialized in this function
      Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      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>
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      e07e835a
    • Mel Gorman's avatar
      cpuset: mm: reduce large amounts of memory barrier related damage v3 · e8bf81d1
      Mel Gorman authored
      commit cc9a6c87 upstream.
      
      Stable note:  Not tracked in Bugzilla. [get|put]_mems_allowed() is extremely
      	expensive and severely impacted page allocator performance. This
      	is part of a series of patches that reduce page allocator overhead.
      
      Commit c0ff7453 ("cpuset,mm: fix no node to alloc memory when
      changing cpuset's mems") wins a super prize for the largest number of
      memory barriers entered into fast paths for one commit.
      
      [get|put]_mems_allowed is incredibly heavy with pairs of full memory
      barriers inserted into a number of hot paths.  This was detected while
      investigating at large page allocator slowdown introduced some time
      after 2.6.32.  The largest portion of this overhead was shown by
      oprofile to be at an mfence introduced by this commit into the page
      allocator hot path.
      
      For extra style points, the commit introduced the use of yield() in an
      implementation of what looks like a spinning mutex.
      
      This patch replaces the full memory barriers on both read and write
      sides with a sequence counter with just read barriers on the fast path
      side.  This is much cheaper on some architectures, including x86.  The
      main bulk of the patch is the retry logic if the nodemask changes in a
      manner that can cause a false failure.
      
      While updating the nodemask, a check is made to see if a false failure
      is a risk.  If it is, the sequence number gets bumped and parallel
      allocators will briefly stall while the nodemask update takes place.
      
      In a page fault test microbenchmark, oprofile samples from
      __alloc_pages_nodemask went from 4.53% of all samples to 1.15%.  The
      actual results were
      
                                   3.3.0-rc3          3.3.0-rc3
                                   rc3-vanilla        nobarrier-v2r1
          Clients   1 UserTime       0.07 (  0.00%)   0.08 (-14.19%)
          Clients   2 UserTime       0.07 (  0.00%)   0.07 (  2.72%)
          Clients   4 UserTime       0.08 (  0.00%)   0.07 (  3.29%)
          Clients   1 SysTime        0.70 (  0.00%)   0.65 (  6.65%)
          Clients   2 SysTime        0.85 (  0.00%)   0.82 (  3.65%)
          Clients   4 SysTime        1.41 (  0.00%)   1.41 (  0.32%)
          Clients   1 WallTime       0.77 (  0.00%)   0.74 (  4.19%)
          Clients   2 WallTime       0.47 (  0.00%)   0.45 (  3.73%)
          Clients   4 WallTime       0.38 (  0.00%)   0.37 (  1.58%)
          Clients   1 Flt/sec/cpu  497620.28 (  0.00%) 520294.53 (  4.56%)
          Clients   2 Flt/sec/cpu  414639.05 (  0.00%) 429882.01 (  3.68%)
          Clients   4 Flt/sec/cpu  257959.16 (  0.00%) 258761.48 (  0.31%)
          Clients   1 Flt/sec      495161.39 (  0.00%) 517292.87 (  4.47%)
          Clients   2 Flt/sec      820325.95 (  0.00%) 850289.77 (  3.65%)
          Clients   4 Flt/sec      1020068.93 (  0.00%) 1022674.06 (  0.26%)
          MMTests Statistics: duration
          Sys Time Running Test (seconds)             135.68    132.17
          User+Sys Time Running Test (seconds)         164.2    160.13
          Total Elapsed Time (seconds)                123.46    120.87
      
      The overall improvement is small but the System CPU time is much
      improved and roughly in correlation to what oprofile reported (these
      performance figures are without profiling so skew is expected).  The
      actual number of page faults is noticeably improved.
      
      For benchmarks like kernel builds, the overall benefit is marginal but
      the system CPU time is slightly reduced.
      
      To test the actual bug the commit fixed I opened two terminals.  The
      first ran within a cpuset and continually ran a small program that
      faulted 100M of anonymous data.  In a second window, the nodemask of the
      cpuset was continually randomised in a loop.
      
      Without the commit, the program would fail every so often (usually
      within 10 seconds) and obviously with the commit everything worked fine.
      With this patch applied, it also worked fine so the fix should be
      functionally equivalent.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Miao Xie <miaox@cn.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Christoph Lameter <cl@linux.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      [bwh: Forward-ported from 3.0 to 3.2: apply the upstream changes
       to get_any_partial()]
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      e8bf81d1
    • Johannes Weiner's avatar
      mm: vmscan: convert global reclaim to per-memcg LRU lists · 01d90f12
      Johannes Weiner authored
      commit b95a2f2d upstream - WARNING: this is a substitute patch.
      
      Stable note: Not tracked in Bugzilla. This is a partial backport of an
      	upstream commit addressing a completely different issue
      	that accidentally contained an important fix. The workload
      	this patch helps was memcached when IO is started in the
      	background. memcached should stay resident but without this patch
      	it gets swapped. Sometimes this manifests as a drop in throughput
      	but mostly it was observed through /proc/vmstat.
      
      Commit [246e87a9: memcg: fix get_scan_count() for small targets] was meant
      to fix a problem whereby small scan targets on memcg were ignored causing
      priority to raise too sharply. It forced scanning to take place if the
      target was small, memcg or kswapd.
      
      From the time it was introduced it caused excessive reclaim by kswapd
      with workloads being pushed to swap that previously would have stayed
      resident. This was accidentally fixed in commit [b95a2f2d: mm: vmscan:
      convert global reclaim to per-memcg LRU lists] by making it harder for
      kswapd to force scan small targets but that patchset is not suitable for
      backporting. This was later changed again by commit [90126375: mm/vmscan:
      push lruvec pointer into get_scan_count()] into a format that looks
      like it would be a straight-forward backport but there is a subtle
      difference due to the use of lruvecs.
      
      The impact of the accidental fix is to make it harder for kswapd to force
      scan small targets by taking zone->all_unreclaimable into account. This
      patch is the closest equivalent available based on what is backported.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      01d90f12
    • Hugh Dickins's avatar
      mm: test PageSwapBacked in lumpy reclaim · 33e037b9
      Hugh Dickins authored
      commit 043bcbe5 upstream.
      
      Stable note: Not tracked in Bugzilla. There were reports of shared
      	mapped pages being unfairly reclaimed in comparison to older kernels.
      	This is being addressed over time. Even though the subject
      	refers to lumpy reclaim, it impacts compaction as well.
      
      Lumpy reclaim does well to stop at a PageAnon when there's no swap, but
      better is to stop at any PageSwapBacked, which includes shmem/tmpfs too.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: default avatarMinchan Kim <minchan@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      33e037b9
    • Minchan Kim's avatar
      mm/vmscan.c: consider swap space when deciding whether to continue reclaim · cef8678e
      Minchan Kim authored
      commit 86cfd3a4 upstream.
      
      Stable note: Not tracked in Bugzilla. This patch reduces kswapd CPU
      	usage on swapless systems with high anonymous memory usage.
      
      It's pointless to continue reclaiming when we have no swap space and lots
      of anon pages in the inactive list.
      
      Without this patch, it is possible when swap is disabled to continue
      trying to reclaim when there are only anonymous pages in the system even
      though that will not make any progress.
      Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      cef8678e
    • Konstantin Khlebnikov's avatar
      vmscan: activate executable pages after first usage · 2addaa3c
      Konstantin Khlebnikov authored
      commit c909e993 upstream.
      
      Stable note: Not tracked in Bugzilla. There were reports of shared
      	mapped pages being unfairly reclaimed in comparison to older kernels.
      	This is being addressed over time.
      
      Logic added in commit 8cab4754 ("vmscan: make mapped executable pages
      the first class citizen") was noticeably weakened in commit
      64574746 ("vmscan: detect mapped file pages used only once").
      
      Currently these pages can become "first class citizens" only after second
      usage.  After this patch page_check_references() will activate they after
      first usage, and executable code gets yet better chance to stay in memory.
      Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
      Cc: Pekka Enberg <penberg@kernel.org>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Nick Piggin <npiggin@kernel.dk>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Cc: Shaohua Li <shaohua.li@intel.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>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      2addaa3c
    • Konstantin Khlebnikov's avatar
      vmscan: promote shared file mapped pages · 1bdeeecd
      Konstantin Khlebnikov authored
      commit 34dbc67a upstream.
      
      Stable note: Not tracked in Bugzilla. There were reports of shared
      	mapped pages being unfairly reclaimed in comparison to older kernels.
      	This is being addressed over time. The specific workload being
      	addressed here in described in paragraph four and while paragraph
      	five says it did not help performance as such, it made a difference
      	to major page faults. I'm aware of at least one bug for a large
      	vendor that was due to increased major faults.
      
      Commit 64574746 ("vmscan: detect mapped file pages used only once")
      greatly decreases lifetime of single-used mapped file pages.
      Unfortunately it also decreases life time of all shared mapped file
      pages.  Because after commit bf3f3bc5 ("mm: don't mark_page_accessed
      in fault path") page-fault handler does not mark page active or even
      referenced.
      
      Thus page_check_references() activates file page only if it was used twice
      while it stays in inactive list, meanwhile it activates anon pages after
      first access.  Inactive list can be small enough, this way reclaimer can
      accidentally throw away any widely used page if it wasn't used twice in
      short period.
      
      After this patch page_check_references() also activate file mapped page at
      first inactive list scan if this page is already used multiple times via
      several ptes.
      
      I found this while trying to fix degragation in rhel6 (~2.6.32) from rhel5
      (~2.6.18).  There a complete mess with >100 web/mail/spam/ftp containers,
      they share all their files but there a lot of anonymous pages: ~500mb
      shared file mapped memory and 15-20Gb non-shared anonymous memory.  In
      this situation major-pagefaults are very costly, because all containers
      share the same page.  In my load kernel created a disproportionate
      pressure on the file memory, compared with the anonymous, they equaled
      only if I raise swappiness up to 150 =)
      
      These patches actually wasn't helped a lot in my problem, but I saw
      noticable (10-20 times) reduce in count and average time of
      major-pagefault in file-mapped areas.
      
      Actually both patches are fixes for commit v2.6.33-5448-g64574746, because
      it was aimed at one scenario (singly used pages), but it breaks the logic
      in other scenarios (shared and/or executable pages)
      Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
      Acked-by: default avatarPekka Enberg <penberg@kernel.org>
      Acked-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Nick Piggin <npiggin@kernel.dk>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Cc: Shaohua Li <shaohua.li@intel.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>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      1bdeeecd
    • Mel Gorman's avatar
      mm: vmscan: check if reclaim should really abort even if compaction_ready() is true for one zone · d1c7dc4c
      Mel Gorman authored
      commit 0cee34fd upstream.
      
      Stable note: Not tracked on Bugzilla. THP and compaction was found to
      	aggressively reclaim pages and stall systems under different
      	situations that was addressed piecemeal over time.
      
      If compaction can proceed for a given zone, shrink_zones() does not
      reclaim any more pages from it.  After commit [e0c23279: vmscan: abort
      reclaim/compaction if compaction can proceed], do_try_to_free_pages()
      tries to finish as soon as possible once one zone can compact.
      
      This was intended to prevent slabs being shrunk unnecessarily but there
      are side-effects.  One is that a small zone that is ready for compaction
      will abort reclaim even if the chances of successfully allocating a THP
      from that zone is small.  It also means that reclaim can return too early
      even though sc->nr_to_reclaim pages were not reclaimed.
      
      This partially reverts the commit until it is proven that slabs are really
      being shrunk unnecessarily but preserves the check to return 1 to avoid
      OOM if reclaim was aborted prematurely.
      
      [aarcange@redhat.com: This patch replaces a revert from Andrea]
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andy Isaacson <adi@hexapodia.org>
      Cc: Nai Xia <nai.xia@gmail.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      d1c7dc4c
    • Mel Gorman's avatar
      mm: vmscan: do not OOM if aborting reclaim to start compaction · b37d0e59
      Mel Gorman authored
      commit 7335084d upstream.
      
      Stable note: Not tracked in Bugzilla. This patch makes later patches
      	easier to apply but otherwise has little to justify it. The
      	problem it fixes was never observed but the source of the
      	theoretical problem did not exist for very long.
      
      During direct reclaim it is possible that reclaim will be aborted so that
      compaction can be attempted to satisfy a high-order allocation.  If this
      decision is made before any pages are reclaimed, it is possible that 0 is
      returned to the page allocator potentially triggering an OOM.  This has
      not been observed but it is a possibility so this patch addresses it.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andy Isaacson <adi@hexapodia.org>
      Cc: Nai Xia <nai.xia@gmail.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      b37d0e59
    • Mel Gorman's avatar
      mm: vmscan: when reclaiming for compaction, ensure there are sufficient free pages available · 553ae61f
      Mel Gorman authored
      commit fe4b1b24 upstream.
      
      Stable note: Not tracked on Bugzilla. THP and compaction was found to
      	aggressively reclaim pages and stall systems under different
      	situations that was addressed piecemeal over time. This patch
      	addresses a problem where the fix regressed THP allocation
      	success rates.
      
      In commit e0887c19 ("vmscan: limit direct reclaim for higher order
      allocations"), Rik noted that reclaim was too aggressive when THP was
      enabled.  In his initial patch he used the number of free pages to decide
      if reclaim should abort for compaction.  My feedback was that reclaim and
      compaction should be using the same logic when deciding if reclaim should
      be aborted.
      
      Unfortunately, this had the effect of reducing THP success rates when the
      workload included something like streaming reads that continually
      allocated pages.  The window during which compaction could run and return
      a THP was too small.
      
      This patch combines Rik's two patches together.  compaction_suitable() is
      still used to decide if reclaim should be aborted to allow compaction is
      used.  However, it will also ensure that there is a reasonable buffer of
      free pages available.  This improves upon the THP allocation success rates
      but bounds the number of pages that are freed for compaction.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: Rik van Riel<riel@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andy Isaacson <adi@hexapodia.org>
      Cc: Nai Xia <nai.xia@gmail.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      553ae61f
    • Mel Gorman's avatar
      mm: compaction: introduce sync-light migration for use by compaction · 4df9e193
      Mel Gorman authored
      commit a6bc32b8 upstream.
      
      Stable note: Not tracked in Buzilla. This was part of a series that
      	reduced interactivity stalls experienced when THP was enabled.
      	These stalls were particularly noticable when copying data
      	to a USB stick but the experiences for users varied a lot.
      
      This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT
      mode that avoids writing back pages to backing storage.  Async compaction
      maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT.
      For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is
      used.
      
      This avoids sync compaction stalling for an excessive length of time,
      particularly when copying files to a USB stick where there might be a
      large number of dirty pages backed by a filesystem that does not support
      ->writepages.
      
      [aarcange@redhat.com: This patch is heavily based on Andrea's work]
      [akpm@linux-foundation.org: fix fs/nfs/write.c build]
      [akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build]
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andy Isaacson <adi@hexapodia.org>
      Cc: Nai Xia <nai.xia@gmail.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      4df9e193
    • Mel Gorman's avatar
      mm: compaction: make isolate_lru_page() filter-aware again · 34c8ed43
      Mel Gorman authored
      commit c8244935 upstream.
      
      Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging
      	information by reducing LRU list churning had the side-effect of
      	reducing THP allocation success rates. This was part of a series
      	to restore the success rates while preserving the reclaim fix.
      
      Commit 39deaf85 ("mm: compaction: make isolate_lru_page() filter-aware")
      noted that compaction does not migrate dirty or writeback pages and that
      is was meaningless to pick the page and re-add it to the LRU list.  This
      had to be partially reverted because some dirty pages can be migrated by
      compaction without blocking.
      
      This patch updates "mm: compaction: make isolate_lru_page" by skipping
      over pages that migration has no possibility of migrating to minimise LRU
      disruption.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: Rik van Riel<riel@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Reviewed-by: default avatarMinchan Kim <minchan@kernel.org>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andy Isaacson <adi@hexapodia.org>
      Cc: Nai Xia <nai.xia@gmail.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      34c8ed43
    • Mel Gorman's avatar
      mm: page allocator: do not call direct reclaim for THP allocations while compaction is deferred · e9a127ba
      Mel Gorman authored
      commit 66199712 upstream.
      
      Stable note: Not tracked in Buzilla. This was part of a series that
      	reduced interactivity stalls experienced when THP was enabled.
      
      If compaction is deferred, direct reclaim is used to try to free enough
      pages for the allocation to succeed.  For small high-orders, this has a
      reasonable chance of success.  However, if the caller has specified
      __GFP_NO_KSWAPD to limit the disruption to the system, it makes more sense
      to fail the allocation rather than stall the caller in direct reclaim.
      This patch skips direct reclaim if compaction is deferred and the caller
      specifies __GFP_NO_KSWAPD.
      
      Async compaction only considers a subset of pages so it is possible for
      compaction to be deferred prematurely and not enter direct reclaim even in
      cases where it should.  To compensate for this, this patch also defers
      compaction only if sync compaction failed.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Acked-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Reviewed-by: Rik van Riel<riel@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andy Isaacson <adi@hexapodia.org>
      Cc: Nai Xia <nai.xia@gmail.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      e9a127ba
    • Mel Gorman's avatar
      mm: compaction: determine if dirty pages can be migrated without blocking within ->migratepage · 41927678
      Mel Gorman authored
      commit b969c4ab upstream.
      
      Stable note: Not tracked in Bugzilla. A fix aimed at preserving page
      	aging information by reducing LRU list churning had the side-effect
      	of reducing THP allocation success rates. This was part of a series
      	to restore the success rates while preserving the reclaim fix.
      
      Asynchronous compaction is used when allocating transparent hugepages to
      avoid blocking for long periods of time.  Due to reports of stalling,
      there was a debate on disabling synchronous compaction but this severely
      impacted allocation success rates.  Part of the reason was that many dirty
      pages are skipped in asynchronous compaction by the following check;
      
      	if (PageDirty(page) && !sync &&
      		mapping->a_ops->migratepage != migrate_page)
      			rc = -EBUSY;
      
      This skips over all mapping aops using buffer_migrate_page() even though
      it is possible to migrate some of these pages without blocking.  This
      patch updates the ->migratepage callback with a "sync" parameter.  It is
      the responsibility of the callback to fail gracefully if migration would
      block.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andy Isaacson <adi@hexapodia.org>
      Cc: Nai Xia <nai.xia@gmail.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      41927678
    • Mel Gorman's avatar
      mm: compaction: allow compaction to isolate dirty pages · 46aadfff
      Mel Gorman authored
      commit a77ebd33 upstream.
      
      Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging
      	information by reducing LRU list churning had the side-effect of
      	reducing THP allocation success rates. This was part of a series
      	to restore the success rates while preserving the reclaim fix.
      
      Short summary: There are severe stalls when a USB stick using VFAT is
      used with THP enabled that are reduced by this series.  If you are
      experiencing this problem, please test and report back and considering I
      have seen complaints from openSUSE and Fedora users on this as well as a
      few private mails, I'm guessing it's a widespread issue.  This is a new
      type of USB-related stall because it is due to synchronous compaction
      writing where as in the past the big problem was dirty pages reaching
      the end of the LRU and being written by reclaim.
      
      Am cc'ing Andrew this time and this series would replace
      mm-do-not-stall-in-synchronous-compaction-for-thp-allocations.patch.
      I'm also cc'ing Dave Jones as he might have merged that patch to Fedora
      for wider testing and ideally it would be reverted and replaced by this
      series.
      
      That said, the later patches could really do with some review.  If this
      series is not the answer then a new direction needs to be discussed
      because as it is, the stalls are unacceptable as the results in this
      leader show.
      
      For testers that try backporting this to 3.1, it won't work because
      there is a non-obvious dependency on not writing back pages in direct
      reclaim so you need those patches too.
      
      Changelog since V5
      o Rebase to 3.2-rc5
      o Tidy up the changelogs a bit
      
      Changelog since V4
      o Added reviewed-bys, credited Andrea properly for sync-light
      o Allow dirty pages without mappings to be considered for migration
      o Bound the number of pages freed for compaction
      o Isolate PageReclaim pages on their own LRU list
      
      This is against 3.2-rc5 and follows on from discussions on "mm: Do
      not stall in synchronous compaction for THP allocations" and "[RFC
      PATCH 0/5] Reduce compaction-related stalls". Initially, the proposed
      patch eliminated stalls due to compaction which sometimes resulted in
      user-visible interactivity problems on browsers by simply never using
      sync compaction. The downside was that THP success allocation rates
      were lower because dirty pages were not being migrated as reported by
      Andrea. His approach at fixing this was nacked on the grounds that
      it reverted fixes from Rik merged that reduced the amount of pages
      reclaimed as it severely impacted his workloads performance.
      
      This series attempts to reconcile the requirements of maximising THP
      usage, without stalling in a user-visible fashion due to compaction
      or cheating by reclaiming an excessive number of pages.
      
      Patch 1 partially reverts commit 39deaf85 to allow migration to isolate
      	dirty pages. This is because migration can move some dirty
      	pages without blocking.
      
      Patch 2 notes that the /proc/sys/vm/compact_memory handler is not using
      	synchronous compaction when it should be. This is unrelated
      	to the reported stalls but is worth fixing.
      
      Patch 3 checks if we isolated a compound page during lumpy scan and
      	account for it properly. For the most part, this affects
      	tracing so it's unrelated to the stalls but worth fixing.
      
      Patch 4 notes that it is possible to abort reclaim early for compaction
      	and return 0 to the page allocator potentially entering the
      	"may oom" path. This has not been observed in practice but
      	the rest of the series potentially makes it easier to happen.
      
      Patch 5 adds a sync parameter to the migratepage callback and gives
      	the callback responsibility for migrating the page without
      	blocking if sync==false. For example, fallback_migrate_page
      	will not call writepage if sync==false. This increases the
      	number of pages that can be handled by asynchronous compaction
      	thereby reducing stalls.
      
      Patch 6 restores filter-awareness to isolate_lru_page for migration.
      	In practice, it means that pages under writeback and pages
      	without a ->migratepage callback will not be isolated
      	for migration.
      
      Patch 7 avoids calling direct reclaim if compaction is deferred but
      	makes sure that compaction is only deferred if sync
      	compaction was used.
      
      Patch 8 introduces a sync-light migration mechanism that sync compaction
      	uses. The objective is to allow some stalls but to not call
      	->writepage which can lead to significant user-visible stalls.
      
      Patch 9 notes that while we want to abort reclaim ASAP to allow
      	compation to go ahead that we leave a very small window of
      	opportunity for compaction to run. This patch allows more pages
      	to be freed by reclaim but bounds the number to a reasonable
      	level based on the high watermark on each zone.
      
      Patch 10 allows slabs to be shrunk even after compaction_ready() is
      	true for one zone. This is to avoid a problem whereby a single
      	small zone can abort reclaim even though no pages have been
      	reclaimed and no suitably large zone is in a usable state.
      
      Patch 11 fixes a problem with the rate of page scanning. As reclaim is
      	rarely stalling on pages under writeback it means that scan
      	rates are very high. This is particularly true for direct
      	reclaim which is not calling writepage. The vmstat figures
      	implied that much of this was busy work with PageReclaim pages
      	marked for immediate reclaim. This patch is a prototype that
      	moves these pages to their own LRU list.
      
      This has been tested and other than 2 USB keys getting trashed,
      nothing horrible fell out. That said, I am a bit unhappy with the
      rescue logic in patch 11 but did not find a better way around it. It
      does significantly reduce scan rates and System CPU time indicating
      it is the right direction to take.
      
      What is of critical importance is that stalls due to compaction
      are massively reduced even though sync compaction was still
      allowed. Testing from people complaining about stalls copying to USBs
      with THP enabled are particularly welcome.
      
      The following tests all involve THP usage and USB keys in some
      way. Each test follows this type of pattern
      
      1. Read from some fast fast storage, be it raw device or file. Each time
         the copy finishes, start again until the test ends
      2. Write a large file to a filesystem on a USB stick. Each time the copy
         finishes, start again until the test ends
      3. When memory is low, start an alloc process that creates a mapping
         the size of physical memory to stress THP allocation. This is the
         "real" part of the test and the part that is meant to trigger
         stalls when THP is enabled. Copying continues in the background.
      4. Record the CPU usage and time to execute of the alloc process
      5. Record the number of THP allocs and fallbacks as well as the number of THP
         pages in use a the end of the test just before alloc exited
      6. Run the test 5 times to get an idea of variability
      7. Between each run, sync is run and caches dropped and the test
         waits until nr_dirty is a small number to avoid interference
         or caching between iterations that would skew the figures.
      
      The individual tests were then
      
      writebackCPDeviceBasevfat
      	Disable THP, read from a raw device (sda), vfat on USB stick
      writebackCPDeviceBaseext4
      	Disable THP, read from a raw device (sda), ext4 on USB stick
      writebackCPDevicevfat
      	THP enabled, read from a raw device (sda), vfat on USB stick
      writebackCPDeviceext4
      	THP enabled, read from a raw device (sda), ext4 on USB stick
      writebackCPFilevfat
      	THP enabled, read from a file on fast storage and USB, both vfat
      writebackCPFileext4
      	THP enabled, read from a file on fast storage and USB, both ext4
      
      The kernels tested were
      
      3.1		3.1
      vanilla		3.2-rc5
      freemore	Patches 1-10
      immediate	Patches 1-11
      andrea		The 8 patches Andrea posted as a basis of comparison
      
      The results are very long unfortunately. I'll start with the case
      where we are not using THP at all
      
      writebackCPDeviceBasevfat
                         3.1.0-vanilla         rc5-vanilla       freemore-v6r1        isolate-v6r1         andrea-v2r1
      System Time         1.28 (    0.00%)   54.49 (-4143.46%)   48.63 (-3687.69%)    4.69 ( -265.11%)   51.88 (-3940.81%)
      +/-                 0.06 (    0.00%)    2.45 (-4305.55%)    4.75 (-8430.57%)    7.46 (-13282.76%)    4.76 (-8440.70%)
      User Time           0.09 (    0.00%)    0.05 (   40.91%)    0.06 (   29.55%)    0.07 (   15.91%)    0.06 (   27.27%)
      +/-                 0.02 (    0.00%)    0.01 (   45.39%)    0.02 (   25.07%)    0.00 (   77.06%)    0.01 (   52.24%)
      Elapsed Time      110.27 (    0.00%)   56.38 (   48.87%)   49.95 (   54.70%)   11.77 (   89.33%)   53.43 (   51.54%)
      +/-                 7.33 (    0.00%)    3.77 (   48.61%)    4.94 (   32.63%)    6.71 (    8.50%)    4.76 (   35.03%)
      THP Active          0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)
      +/-                 0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)
      Fault Alloc         0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)
      +/-                 0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)
      Fault Fallback      0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)
      +/-                 0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)    0.00 (    0.00%)
      
      The THP figures are obviously all 0 because THP was enabled. The
      main thing to watch is the elapsed times and how they compare to
      times when THP is enabled later. It's also important to note that
      elapsed time is improved by this series as System CPu time is much
      reduced.
      
      writebackCPDevicevfat
      
                         3.1.0-vanilla         rc5-vanilla       freemore-v6r1        isolate-v6r1         andrea-v2r1
      System Time         1.22 (    0.00%)   13.89 (-1040.72%)   46.40 (-3709.20%)    4.44 ( -264.37%)   47.37 (-3789.33%)
      +/-                 0.06 (    0.00%)   22.82 (-37635.56%)    3.84 (-6249.44%)    6.48 (-10618.92%)    6.60
      (-10818.53%)
      User Time           0.06 (    0.00%)    0.06 (   -6.90%)    0.05 (   17.24%)    0.05 (   13.79%)    0.04 (   31.03%)
      +/-                 0.01 (    0.00%)    0.01 (   33.33%)    0.01 (   33.33%)    0.01 (   39.14%)    0.01 (   25.46%)
      Elapsed Time     10445.54 (    0.00%) 2249.92 (   78.46%)   70.06 (   99.33%)   16.59 (   99.84%)  472.43 (
      95.48%)
      +/-               643.98 (    0.00%)  811.62 (  -26.03%)   10.02 (   98.44%)    7.03 (   98.91%)   59.99 (   90.68%)
      THP Active         15.60 (    0.00%)   35.20 (  225.64%)   65.00 (  416.67%)   70.80 (  453.85%)   62.20 (  398.72%)
      +/-                18.48 (    0.00%)   51.29 (  277.59%)   15.99 (   86.52%)   37.91 (  205.18%)   22.02 (  119.18%)
      Fault Alloc       121.80 (    0.00%)   76.60 (   62.89%)  155.40 (  127.59%)  181.20 (  148.77%)  286.60 (  235.30%)
      +/-                73.51 (    0.00%)   61.11 (   83.12%)   34.89 (   47.46%)   31.88 (   43.36%)   68.13 (   92.68%)
      Fault Fallback    881.20 (    0.00%)  926.60 (   -5.15%)  847.60 (    3.81%)  822.00 (    6.72%)  716.60 (   18.68%)
      +/-                73.51 (    0.00%)   61.26 (   16.67%)   34.89 (   52.54%)   31.65 (   56.94%)   67.75 (    7.84%)
      MMTests Statistics: duration
      User/Sys Time Running Test (seconds)       3540.88   1945.37    716.04     64.97   1937.03
      Total Elapsed Time (seconds)              52417.33  11425.90    501.02    230.95   2520.28
      
      The first thing to note is the "Elapsed Time" for the vanilla kernels
      of 2249 seconds versus 56 with THP disabled which might explain the
      reports of USB stalls with THP enabled. Applying the patches brings
      performance in line with THP-disabled performance while isolating
      pages for immediate reclaim from the LRU cuts down System CPU time.
      
      The "Fault Alloc" success rate figures are also improved. The vanilla
      kernel only managed to allocate 76.6 pages on average over the course
      of 5 iterations where as applying the series allocated 181.20 on
      average albeit it is well within variance. It's worth noting that
      applies the series at least descreases the amount of variance which
      implies an improvement.
      
      Andrea's series had a higher success rate for THP allocations but
      at a severe cost to elapsed time which is still better than vanilla
      but still much worse than disabling THP altogether. One can bring my
      series close to Andrea's by removing this check
      
              /*
               * If compaction is deferred for high-order allocations, it is because
               * sync compaction recently failed. In this is the case and the caller
               * has requested the system not be heavily disrupted, fail the
               * allocation now instead of entering direct reclaim
               */
              if (deferred_compaction && (gfp_mask & __GFP_NO_KSWAPD))
                      goto nopage;
      
      I didn't include a patch that removed the above check because hurting
      overall performance to improve the THP figure is not what the average
      user wants. It's something to consider though if someone really wants
      to maximise THP usage no matter what it does to the workload initially.
      
      This is summary of vmstat figures from the same test.
      
                                             3.1.0-vanilla rc5-vanilla freemore-v6r1 isolate-v6r1 andrea-v2r1
      Page Ins                                  3257266139  1111844061    17263623    10901575   161423219
      Page Outs                                   81054922    30364312     3626530     3657687     8753730
      Swap Ins                                        3294        2851        6560        4964        4592
      Swap Outs                                     390073      528094      620197      790912      698285
      Direct pages scanned                      1077581700  3024951463  1764930052   115140570  5901188831
      Kswapd pages scanned                        34826043     7112868     2131265     1686942     1893966
      Kswapd pages reclaimed                      28950067     4911036     1246044      966475     1497726
      Direct pages reclaimed                     805148398   280167837     3623473     2215044    40809360
      Kswapd efficiency                                83%         69%         58%         57%         79%
      Kswapd velocity                              664.399     622.521    4253.852    7304.360     751.490
      Direct efficiency                                74%          9%          0%          1%          0%
      Direct velocity                            20557.737  264745.137 3522673.849  498551.938 2341481.435
      Percentage direct scans                          96%         99%         99%         98%         99%
      Page writes by reclaim                        722646      529174      620319      791018      699198
      Page writes file                              332573        1080         122         106         913
      Page writes anon                              390073      528094      620197      790912      698285
      Page reclaim immediate                             0  2552514720  1635858848   111281140  5478375032
      Page rescued immediate                             0           0           0       87848           0
      Slabs scanned                                  23552       23552        9216        8192        9216
      Direct inode steals                              231           0           0           0           0
      Kswapd inode steals                                0           0           0           0           0
      Kswapd skipped wait                            28076         786           0          61           6
      THP fault alloc                                  609         383         753         906        1433
      THP collapse alloc                                12           6           0           0           6
      THP splits                                       536         211         456         593        1136
      THP fault fallback                              4406        4633        4263        4110        3583
      THP collapse fail                                120         127           0           0           4
      Compaction stalls                               1810         728         623         779        3200
      Compaction success                               196          53          60          80         123
      Compaction failures                             1614         675         563         699        3077
      Compaction pages moved                        193158       53545      243185      333457      226688
      Compaction move failure                         9952        9396       16424       23676       45070
      
      The main things to look at are
      
      1. Page In/out figures are much reduced by the series.
      
      2. Direct page scanning is incredibly high (264745.137 pages scanned
         per second on the vanilla kernel) but isolating PageReclaim pages
         on their own list reduces the number of pages scanned significantly.
      
      3. The fact that "Page rescued immediate" is a positive number implies
         that we sometimes race removing pages from the LRU_IMMEDIATE list
         that need to be put back on a normal LRU but it happens only for
         0.07% of the pages marked for immediate reclaim.
      
      writebackCPDeviceext4
                         3.1.0-vanilla         rc5-vanilla       freemore-v6r1        isolate-v6r1         andrea-v2r1
      System Time         1.51 (    0.00%)    1.77 (  -17.66%)    1.46 (    2.92%)    1.15 (   23.77%)    1.89 (  -25.63%)
      +/-                 0.27 (    0.00%)    0.67 ( -148.52%)    0.33 (  -22.76%)    0.30 (  -11.15%)    0.19 (   30.16%)
      User Time           0.03 (    0.00%)    0.04 (  -37.50%)    0.05 (  -62.50%)    0.07 ( -112.50%)    0.04 (  -18.75%)
      +/-                 0.01 (    0.00%)    0.02 ( -146.64%)    0.02 (  -97.91%)    0.02 (  -75.59%)    0.02 (  -63.30%)
      Elapsed Time      124.93 (    0.00%)  114.49 (    8.36%)   96.77 (   22.55%)   27.48 (   78.00%)  205.70 (  -64.65%)
      +/-                20.20 (    0.00%)   74.39 ( -268.34%)   59.88 ( -196.48%)    7.72 (   61.79%)   25.03 (  -23.95%)
      THP Active        161.80 (    0.00%)   83.60 (   51.67%)  141.20 (   87.27%)   84.60 (   52.29%)   82.60 (   51.05%)
      +/-                71.95 (    0.00%)   43.80 (   60.88%)   26.91 (   37.40%)   59.02 (   82.03%)   52.13 (   72.45%)
      Fault Alloc       471.40 (    0.00%)  228.60 (   48.49%)  282.20 (   59.86%)  225.20 (   47.77%)  388.40 (   82.39%)
      +/-                88.07 (    0.00%)   87.42 (   99.26%)   73.79 (   83.78%)  109.62 (  124.47%)   82.62 (   93.81%)
      Fault Fallback    531.60 (    0.00%)  774.60 (  -45.71%)  720.80 (  -35.59%)  777.80 (  -46.31%)  614.80 (  -15.65%)
      +/-                88.07 (    0.00%)   87.26 (    0.92%)   73.79 (   16.22%)  109.62 (  -24.47%)   82.29 (    6.56%)
      MMTests Statistics: duration
      User/Sys Time Running Test (seconds)         50.22     33.76     30.65     24.14    128.45
      Total Elapsed Time (seconds)               1113.73   1132.19   1029.45    759.49   1707.26
      
      Similar test but the USB stick is using ext4 instead of vfat. As
      ext4 does not use writepage for migration, the large stalls due to
      compaction when THP is enabled are not observed. Still, isolating
      PageReclaim pages on their own list helped completion time largely
      by reducing the number of pages scanned by direct reclaim although
      time spend in congestion_wait could also be a factor.
      
      Again, Andrea's series had far higher success rates for THP allocation
      at the cost of elapsed time. I didn't look too closely but a quick
      look at the vmstat figures tells me kswapd reclaimed 8 times more pages
      than the patch series and direct reclaim reclaimed roughly three times
      as many pages. It follows that if memory is aggressively reclaimed,
      there will be more available for THP.
      
      writebackCPFilevfat
                         3.1.0-vanilla         rc5-vanilla       freemore-v6r1        isolate-v6r1         andrea-v2r1
      System Time         1.76 (    0.00%)   29.10 (-1555.52%)   46.01 (-2517.18%)    4.79 ( -172.35%)   54.89 (-3022.53%)
      +/-                 0.14 (    0.00%)   25.61 (-18185.17%)    2.15 (-1434.83%)    6.60 (-4610.03%)    9.75
      (-6863.76%)
      User Time           0.05 (    0.00%)    0.07 (  -45.83%)    0.05 (   -4.17%)    0.06 (  -29.17%)    0.06 (  -16.67%)
      +/-                 0.02 (    0.00%)    0.02 (   20.11%)    0.02 (   -3.14%)    0.01 (   31.58%)    0.01 (   47.41%)
      Elapsed Time     22520.79 (    0.00%) 1082.85 (   95.19%)   73.30 (   99.67%)   32.43 (   99.86%)  291.84 (  98.70%)
      +/-              7277.23 (    0.00%)  706.29 (   90.29%)   19.05 (   99.74%)   17.05 (   99.77%)  125.55 (   98.27%)
      THP Active         83.80 (    0.00%)   12.80 (   15.27%)   15.60 (   18.62%)   13.00 (   15.51%)    0.80 (    0.95%)
      +/-                66.81 (    0.00%)   20.19 (   30.22%)    5.92 (    8.86%)   15.06 (   22.54%)    1.17 (    1.75%)
      Fault Alloc       171.00 (    0.00%)   67.80 (   39.65%)   97.40 (   56.96%)  125.60 (   73.45%)  133.00 (   77.78%)
      +/-                82.91 (    0.00%)   30.69 (   37.02%)   53.91 (   65.02%)   55.05 (   66.40%)   21.19 (   25.56%)
      Fault Fallback    832.00 (    0.00%)  935.20 (  -12.40%)  906.00 (   -8.89%)  877.40 (   -5.46%)  870.20 (   -4.59%)
      +/-                82.91 (    0.00%)   30.69 (   62.98%)   54.01 (   34.86%)   55.05 (   33.60%)   20.91 (   74.78%)
      MMTests Statistics: duration
      User/Sys Time Running Test (seconds)       7229.81    928.42    704.52     80.68   1330.76
      Total Elapsed Time (seconds)             112849.04   5618.69    571.11    360.54   1664.28
      
      In this case, the test is reading/writing only from filesystems but as
      it's vfat, it's slow due to calling writepage during compaction. Little
      to observe really - the time to complete the test goes way down
      with the series applied and THP allocation success rates go up in
      comparison to 3.2-rc5.  The success rates are lower than 3.1.0 but
      the elapsed time for that kernel is abysmal so it is not really a
      sensible comparison.
      
      As before, Andrea's series allocates more THPs at the cost of overall
      performance.
      
      writebackCPFileext4
                         3.1.0-vanilla         rc5-vanilla       freemore-v6r1        isolate-v6r1         andrea-v2r1
      System Time         1.51 (    0.00%)    1.77 (  -17.66%)    1.46 (    2.92%)    1.15 (   23.77%)    1.89 (  -25.63%)
      +/-                 0.27 (    0.00%)    0.67 ( -148.52%)    0.33 (  -22.76%)    0.30 (  -11.15%)    0.19 (   30.16%)
      User Time           0.03 (    0.00%)    0.04 (  -37.50%)    0.05 (  -62.50%)    0.07 ( -112.50%)    0.04 (  -18.75%)
      +/-                 0.01 (    0.00%)    0.02 ( -146.64%)    0.02 (  -97.91%)    0.02 (  -75.59%)    0.02 (  -63.30%)
      Elapsed Time      124.93 (    0.00%)  114.49 (    8.36%)   96.77 (   22.55%)   27.48 (   78.00%)  205.70 (  -64.65%)
      +/-                20.20 (    0.00%)   74.39 ( -268.34%)   59.88 ( -196.48%)    7.72 (   61.79%)   25.03 (  -23.95%)
      THP Active        161.80 (    0.00%)   83.60 (   51.67%)  141.20 (   87.27%)   84.60 (   52.29%)   82.60 (   51.05%)
      +/-                71.95 (    0.00%)   43.80 (   60.88%)   26.91 (   37.40%)   59.02 (   82.03%)   52.13 (   72.45%)
      Fault Alloc       471.40 (    0.00%)  228.60 (   48.49%)  282.20 (   59.86%)  225.20 (   47.77%)  388.40 (   82.39%)
      +/-                88.07 (    0.00%)   87.42 (   99.26%)   73.79 (   83.78%)  109.62 (  124.47%)   82.62 (   93.81%)
      Fault Fallback    531.60 (    0.00%)  774.60 (  -45.71%)  720.80 (  -35.59%)  777.80 (  -46.31%)  614.80 (  -15.65%)
      +/-                88.07 (    0.00%)   87.26 (    0.92%)   73.79 (   16.22%)  109.62 (  -24.47%)   82.29 (    6.56%)
      MMTests Statistics: duration
      User/Sys Time Running Test (seconds)         50.22     33.76     30.65     24.14    128.45
      Total Elapsed Time (seconds)               1113.73   1132.19   1029.45    759.49   1707.26
      
      Same type of story - elapsed times go down. In this case, allocation
      success rates are roughtly the same. As before, Andrea's has higher
      success rates but takes a lot longer.
      
      Overall the series does reduce latencies and while the tests are
      inherency racy as alloc competes with the cp processes, the variability
      was included. The THP allocation rates are not as high as they could
      be but that is because we would have to be more aggressive about
      reclaim and compaction impacting overall performance.
      
      This patch:
      
      Commit 39deaf85 ("mm: compaction: make isolate_lru_page() filter-aware")
      noted that compaction does not migrate dirty or writeback pages and that
      is was meaningless to pick the page and re-add it to the LRU list.
      
      What was missed during review is that asynchronous migration moves dirty
      pages if their ->migratepage callback is migrate_page() because these can
      be moved without blocking.  This potentially impacted hugepage allocation
      success rates by a factor depending on how many dirty pages are in the
      system.
      
      This patch partially reverts 39deaf85 to allow migration to isolate dirty
      pages again.  This increases how much compaction disrupts the LRU but that
      is addressed later in the series.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reviewed-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Andy Isaacson <adi@hexapodia.org>
      Cc: Nai Xia <nai.xia@gmail.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      46aadfff
    • Mel Gorman's avatar
      mm: reduce the amount of work done when updating min_free_kbytes · c653414d
      Mel Gorman authored
      commit 938929f1 upstream.
      
      Stable note: Fixes https://bugzilla.novell.com/show_bug.cgi?id=726210 .
              Large machines with 1TB or more of RAM take a long time to boot
              without this patch and may spew out soft lockup warnings.
      
      When min_free_kbytes is updated, some pageblocks are marked
      MIGRATE_RESERVE.  Ordinarily, this work is unnoticable as it happens early
      in boot but on large machines with 1TB of memory, this has been reported
      to delay boot times, probably due to the NUMA distances involved.
      
      The bulk of the work is due to calling calling pageblock_is_reserved() an
      unnecessary amount of times and accessing far more struct page metadata
      than is necessary.  This patch significantly reduces the amount of work
      done by setup_zone_migrate_reserve() improving boot times on 1TB machines.
      
      [akpm@linux-foundation.org: coding-style fixes]
      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>
      Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
      c653414d
  2. 25 Jul, 2012 7 commits