Dave Chinner reported the following on https://lkml.org/lkml/2015/3/1/226

  Across the board the 4.0-rc1 numbers are much slower, and the degradation
  is far worse when using the large memory footprint configs. Perf points
  straight at the cause - this is from 4.0-rc1 on the "-o bhash=101073" config:

   -   56.07%    56.07%  [kernel]            [k] default_send_IPI_mask_sequence_phys
      - default_send_IPI_mask_sequence_phys
         - 99.99% physflat_send_IPI_mask
            - 99.37% native_send_call_func_ipi
                 smp_call_function_many
               - native_flush_tlb_others
                  - 99.85% flush_tlb_page
                       ptep_clear_flush
                       try_to_unmap_one
                       rmap_walk
                       try_to_unmap
                       migrate_pages
                       migrate_misplaced_page
                     - handle_mm_fault
                        - 99.73% __do_page_fault
                             trace_do_page_fault
                             do_async_page_fault
                           + async_page_fault
              0.63% native_send_call_func_single_ipi
                 generic_exec_single
                 smp_call_function_single

This is showing excessive migration activity even though excessive
migrations are meant to get throttled.  Normally, the scan rate is tuned
on a per-task basis depending on the locality of faults.  However, if
migrations fail for any reason then the PTE scanner may scan faster if
the faults continue to be remote.  This means there is higher system CPU
overhead and fault trapping at exactly the time we know that migrations
cannot happen.  This patch tracks when migration failures occur and
slows the PTE scanner.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Dave Chinner <david@fromorbit.com>
Tested-by: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull libata fix from Tejun Heo:
 "One patch to fix a regression from the recent switch to blk-mq tag
  allocation which can cause oops on SAS-attached SATA drives"

* 'for-4.0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  ata: Add a new flag to destinguish sas controller

Pull regulator fixes from Mark Brown:
 "Two fixes here, one typo fix in the documentation and one fix for a
  system hang with one of the Palmas chips caused by the use of an
  incorrect offset being provided for one of the registers"

* tag 'regulator-fix-v4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator: Fix documentation for regmap in the config
  regulator: palmas: Correct TPS659038 register definition for REGEN2

Pull regmap fix from Mark Brown:
 "This patch fixes a bad interaction between the support that was added
  for having regmaps without devices for early system controller
  initialization and the trace support.

  There's a very good analysis of the actual issue in the commit message
  for the change"

* tag 'regmap-fix-v4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: introduce regmap_name to fix syscon regmap trace events

Pull networking fixes from David Miller:

 1) Validate iov ranges before feeding them into iov_iter_init(), from
    Al Viro.

 2) We changed copy_from_msghdr_from_user() to zero out the msg_namelen
    is a NULL pointer is given for the msg_name.  Do the same in the
    compat code too.  From Catalin Marinas.

 3) Fix partially initialized tuples in netfilter conntrack helper, from
    Ian Wilson.

 4) Missing continue; statement in nft_hash walker can lead to crashes,
    from Herbert Xu.

 5) tproxy_tg6_check looks for IP6T_INV_PROTO in ->flags instead of
    ->invflags, fix from Pablo Neira Ayuso.

 6) Incorrect memory account of TCP FINs can result in negative socket
    memory accounting values.  Fix from Josh Hunt.

 7) Don't allow virtual functions to enable VLAN promiscuous mode in
    be2net driver, from Vasundhara Volam.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  netfilter: nft_compat: set IP6T_F_PROTO flag if protocol is set
  cx82310_eth: wait for firmware to become ready
  net: validate the range we feed to iov_iter_init() in sys_sendto/sys_recvfrom
  net: compat: Update get_compat_msghdr() to match copy_msghdr_from_user() behaviour
  be2net: use PCI MMIO read instead of config read for errors
  be2net: restrict MODIFY_EQ_DELAY cmd to a max of 8 EQs
  be2net: Prevent VFs from enabling VLAN promiscuous mode
  tcp: fix tcp fin memory accounting
  ipv6: fix backtracking for throw routes
  net: ethernet: pcnet32: Setup the SRAM and NOUFLO on Am79C97{3, 5}
  ipv6: call ipv6_proxy_select_ident instead of ipv6_select_ident in udp6_ufo_fragment
  netfilter: xt_TPROXY: fix invflags check in tproxy_tg6_check()
  netfilter: restore rule tracing via nfnetlink_log
  netfilter: nf_tables: allow to change chain policy without hook if it exists
  netfilter: Fix potential crash in nft_hash walker
  netfilter: Zero the tuple in nfnl_cthelper_parse_tuple()

Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for your net tree,
they are:

1) Fix missing initialization of tuple structure in nfnetlink_cthelper
   to avoid mismatches when looking up to attach userspace helpers to
   flows, from Ian Wilson.

2) Fix potential crash in nft_hash when we hit -EAGAIN in
   nft_hash_walk(), from Herbert Xu.

3) We don't need to indicate the hook information to update the
   basechain default policy in nf_tables.

4) Restore tracing over nfnetlink_log due to recent rework to
   accomodate logging infrastructure into nf_tables.

5) Fix wrong IP6T_INV_PROTO check in xt_TPROXY.

6) Set IP6T_F_PROTO flag in nft_compat so we can use SYNPROXY6 and
   REJECT6 from xt over nftables.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Pull SCSI target fixes from Nicholas Bellinger:
 "Here are current target-pending fixes for v4.0-rc5 code that have made
  their way into the queue over the last weeks.

  The fixes this round include:

   - Fix long-standing iser-target logout bug related to early
     conn_logout_comp completion, resulting in iscsi_conn use-after-tree
     OOpsen.  (Sagi + nab)

   - Fix long-standing tcm_fc bug in ft_invl_hw_context() failure
     handing for DDP hw offload.  (DanC)

   - Fix incorrect use of unprotected __transport_register_session() in
     tcm_qla2xxx + other single local se_node_acl fabrics.  (Bart)

   - Fix reference leak in target_submit_cmd() -> target_get_sess_cmd()
     for ack_kref=1 failure path.  (Bart)

   - Fix pSCSI backend ->get_device_type() statistics OOPs with
     un-configured device.  (Olaf + nab)

   - Fix virtual LUN=0 target_configure_device failure OOPs at modprobe
     time.  (Claudio + nab)

   - Fix FUA write false positive failure regression in v4.0-rc1 code.
     (Christophe Vu-Brugier + HCH)"

* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
  target: do not reject FUA CDBs when write cache is enabled but emulate_write_cache is 0
  target: Fix virtual LUN=0 target_configure_device failure OOPs
  target/pscsi: Fix NULL pointer dereference in get_device_type
  tcm_fc: missing curly braces in ft_invl_hw_context()
  target: Fix reference leak in target_get_sess_cmd() error path
  loop/usb/vhost-scsi/xen-scsiback: Fix use of __transport_register_session
  tcm_qla2xxx: Fix incorrect use of __transport_register_session
  iscsi-target: Avoid early conn_logout_comp for iser connections
  Revert "iscsi-target: Avoid IN_LOGOUT failure case for iser-target"
  target: Disallow changing of WRITE cache/FUA attrs after export

Pull devicemapper fixes from Mike Snitzer:
 "A handful of stable fixes for DM:
   - fix thin target to always zero-fill reads to unprovisioned blocks
   - fix to interlock device destruction's suspend from internal
     suspends
   - fix 2 snapshot exception store handover bugs
   - fix dm-io to cope with DISCARD and WRITE_SAME capabilities changing"

* tag 'dm-4.0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm io: deal with wandering queue limits when handling REQ_DISCARD and REQ_WRITE_SAME
  dm snapshot: suspend merging snapshot when doing exception handover
  dm snapshot: suspend origin when doing exception handover
  dm: hold suspend_lock while suspending device during device deletion
  dm thin: fix to consistently zero-fill reads to unprovisioned blocks

A check that rejects a CDB with FUA bit set if no write cache is
emulated was added by the following commit:

  fde9f50 target: Add sanity checks for DPO/FUA bit usage

The condition is as follows:

  if (!dev->dev_attrib.emulate_fua_write ||
      !dev->dev_attrib.emulate_write_cache)

However, this check is wrong if the backend device supports WCE but
"emulate_write_cache" is disabled.

This patch uses se_dev_check_wce() (previously named
spc_check_dev_wce) to invoke transport->get_write_cache() if the
device has a write cache or check the "emulate_write_cache" attribute
otherwise.

Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>