When the tick is stopped and we reach the dynticks evaluation code on
IRQ exit, we perform a soft tick restart if we observe an expired timer
from there. It means we program the nearest possible tick but we stay in
dynticks mode (ts->tick_stopped = 1) because we may need to stop the tick
again after that expired timer is handled.

Now this solution works most of the time but if we suffer an IRQ storm
and those interrupts trigger faster than the hardware clockevents min
delay, our tick won't fire until that IRQ storm is finished.

Here is the problem: on IRQ exit we reprog the timer to at least
NOW() + min_clockevents_delay. Another IRQ fires before the tick so we
reschedule again to NOW() + min_clockevents_delay, etc... The tick
is eternally rescheduled min_clockevents_delay ahead.

A solution is to simply remove this soft tick restart. After all
the normal dynticks evaluation path can handle 0 delay just fine. And
by doing that we benefit from the optimization branch which avoids
clock reprogramming if the clockevents deadline hasn't changed since
the last reprog. This fixes our issue because we don't do repetitive
clock reprog that always add hardware min delay.

As a side effect it should even optimize the 0 delay path in general.
Reported-and-tested-by: NOctavian Purdila <octavian.purdila@nxp.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1496328429-13317-1-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Handle tick interrupts whose regs are NULL, out of general paranoia. It happens
when hrtimer_interrupt() is called from non-interrupt contexts, such as hotplug
CPU down events.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

This restores commit:

  24b91e36: ("nohz: Fix collision between tick and other hrtimers")

... which got reverted by commit:

  558e8e27: ('Revert "nohz: Fix collision between tick and other hrtimers"')

... due to a regression where CPUs spuriously stopped ticking.

The bug happened when a tick fired too early past its expected expiration:
on IRQ exit the tick was scheduled again to the same deadline but skipped
reprogramming because ts->next_tick still kept in cache the deadline.
This has been fixed now with resetting ts->next_tick from the tick
itself. Extra care has also been taken to prevent from obsolete values
throughout CPU hotplug operations.

When the tick is stopped and an interrupt occurs afterward, we check on
that interrupt exit if the next tick needs to be rescheduled. If it
doesn't need any update, we don't want to do anything.

In order to check if the tick needs an update, we compare it against the
clockevent device deadline. Now that's a problem because the clockevent
device is at a lower level than the tick itself if it is implemented
on top of hrtimer.

Every hrtimer share this clockevent device. So comparing the next tick
deadline against the clockevent device deadline is wrong because the
device may be programmed for another hrtimer whose deadline collides
with the tick. As a result we may end up not reprogramming the tick
accidentally.

In a worst case scenario under full dynticks mode, the tick stops firing
as it is supposed to every 1hz, leaving /proc/stat stalled:

      Task in a full dynticks CPU
      ----------------------------

      * hrtimer A is queued 2 seconds ahead
      * the tick is stopped, scheduled 1 second ahead
      * tick fires 1 second later
      * on tick exit, nohz schedules the tick 1 second ahead but sees
        the clockevent device is already programmed to that deadline,
        fooled by hrtimer A, the tick isn't rescheduled.
      * hrtimer A is cancelled before its deadline
      * tick never fires again until an interrupt happens...

In order to fix this, store the next tick deadline to the tick_sched
local structure and reuse that value later to check whether we need to
reprogram the clock after an interrupt.

On the other hand, ts->sleep_length still wants to know about the next
clock event and not just the tick, so we want to improve the related
comment to avoid confusion.
Reported-and-tested-by: NTim Wright <tim@binbash.co.uk>
Reported-and-tested-by: NPavel Machek <pavel@ucw.cz>
Reported-by: NJames Hartsock <hartsjc@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NRik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1492783255-5051-2-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Pull pstore fix from Kees Cook:
 "Fix bad EFI vars iterator usage"

* tag 'pstore-v4.12-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  efi-pstore: Fix read iter after pstore API refactor

During the internal pstore API refactoring, the EFI vars read entry was
accidentally made to update a stack variable instead of the pstore
private data pointer. This corrects the problem (and removes the now
needless argument).

Fixes: 125cc42b ("pstore: Replace arguments for read() API")
Signed-off-by: NKees Cook <keescook@chromium.org>

Pull s390 fixes from Martin Schwidefsky:

 - convert the debug feature to refcount_t

 - reduce the copy size for strncpy_from_user

 - 8 bug fixes

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/virtio: change virtio_feature_desc:features type to __le32
  s390: convert debug_info.ref_count from atomic_t to refcount_t
  s390: move _text symbol to address higher than zero
  s390/qdio: increase string buffer size
  s390/ccwgroup: increase string buffer size
  s390/topology: let topology_mnest_limit() return unsigned char
  s390/uaccess: use sane length for __strncpy_from_user()
  s390/uprobes: fix compile for !KPROBES
  s390/ftrace: fix compile for !MODULES
  s390/cputime: fix incorrect system time

Pull EDAC fix from Borislav Petkov:
 "A single amd64_edac fix correcting chip select sizes reporting on
  F17h"

* tag 'edac_fix_for_4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp:
  EDAC, amd64: Fix reporting of Chip Select sizes on Fam17h

Pull networking fixes from David Miller:

 1) Track alignment in BPF verifier so that legitimate programs won't be
    rejected on !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS architectures.

 2) Make tail calls work properly in arm64 BPF JIT, from Deniel
    Borkmann.

 3) Make the configuration and semantics Generic XDP make more sense and
    don't allow both generic XDP and a driver specific instance to be
    active at the same time. Also from Daniel.

 4) Don't crash on resume in xen-netfront, from Vitaly Kuznetsov.

 5) Fix use-after-free in VRF driver, from Gao Feng.

 6) Use netdev_alloc_skb_ip_align() to avoid unaligned IP headers in
    qca_spi driver, from Stefan Wahren.

 7) Always run cleanup routines in BPF samples when we get SIGTERM, from
    Andy Gospodarek.

 8) The mdio phy code should bring PHYs out of reset using the shared
    GPIO lines before invoking bus->reset(). From Florian Fainelli.

 9) Some USB descriptor access endian fixes in various drivers from
    Johan Hovold.

10) Handle PAUSE advertisements properly in mlx5 driver, from Gal
    Pressman.

11) Fix reversed test in mlx5e_setup_tc(), from Saeed Mahameed.

12) Cure netdev leak in AF_PACKET when using timestamping via control
    messages. From Douglas Caetano dos Santos.

13) netcp doesn't support HWTSTAMP_FILTER_ALl, reject it. From Miroslav
    Lichvar.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (52 commits)
  ldmvsw: stop the clean timer at beginning of remove
  ldmvsw: unregistering netdev before disable hardware
  net: netcp: fix check of requested timestamping filter
  ipv6: avoid dad-failures for addresses with NODAD
  qed: Fix uninitialized data in aRFS infrastructure
  mdio: mux: fix device_node_continue.cocci warnings
  net/packet: fix missing net_device reference release
  net/mlx4_core: Use min3 to select number of MSI-X vectors
  macvlan: Fix performance issues with vlan tagged packets
  net: stmmac: use correct pointer when printing normal descriptor ring
  net/mlx5: Use underlay QPN from the root name space
  net/mlx5e: IPoIB, Only support regular RQ for now
  net/mlx5e: Fix setup TC ndo
  net/mlx5e: Fix ethtool pause support and advertise reporting
  net/mlx5e: Use the correct pause values for ethtool advertising
  vmxnet3: ensure that adapter is in proper state during force_close
  sfc: revert changes to NIC revision numbers
  net: ch9200: add missing USB-descriptor endianness conversions
  net: irda: irda-usb: fix firmware name on big-endian hosts
  net: dsa: mv88e6xxx: add default case to switch
  ...

Pull cifs fixes from Steve French:
 "A set of minor cifs fixes"

* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
  [CIFS] Minor cleanup of xattr query function
  fs: cifs: transport: Use time_after for time comparison
  SMB2: Fix share type handling
  cifs: cifsacl: Use a temporary ops variable to reduce code length
  Don't delay freeing mids when blocked on slow socket write of request
  CIFS: silence lockdep splat in cifs_relock_file()

Shannon Nelson says:

====================
ldmvsw: port removal stability

Under heavy reboot stress testing we found a couple of timing issues
when removing the device that could cause the kernel great heartburn,
addressed by these two patches.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Stop the clean timer earlier to be sure there's no asynchronous
interference while stopping the port.

Orabug: 25748241
Signed-off-by: NShannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When running LDom binding/unbinding test, kernel may panic
in ldmvsw_open(). It is more likely that because we're removing
the ldc connection before unregistering the netdev in vsw_port_remove(),
we set up a window of time where one process could be removing the
device while another trying to UP the device. This also sometimes causes
vio handshake error due to opening a device without closing it completely.
We should unregister the netdev before we disable the "hardware".

Orabug: 25980913, 25925306
Signed-off-by: NThomas Tai <thomas.tai@oracle.com>
Signed-off-by: NShannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver doesn't support timestamping of all received packets and
should return error when trying to enable the HWTSTAMP_FILTER_ALL
filter.

Cc: WingMan Kwok <w-kwok2@ti.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: NMiroslav Lichvar <mlichvar@redhat.com>
Acked-by: NRichard Cochran <richardcochran@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Saeed Mahameed says:

====================
Mellanox, mlx5 fixes 2017-05-12

This series contains some mlx5 fixes for net.
Please pull and let me know if there's any problem.

For -stable:
("net/mlx5e: Fix ethtool pause support and advertise reporting") kernels >= 4.8
("net/mlx5e: Use the correct pause values for ethtool advertising") kernels >= 4.8

v1->v2:
 Dropped statistics spinlock patch, it needs some extra work.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Every address gets added with TENTATIVE flag even for the addresses with
IFA_F_NODAD flag and dad-work is scheduled for them. During this DAD process
we realize it's an address with NODAD and complete the process without
sending any probe. However the TENTATIVE flags stays on the
address for sometime enough to cause misinterpretation when we receive a NS.
While processing NS, if the address has TENTATIVE flag, we mark it DADFAILED
and endup with an address that was originally configured as NODAD with
DADFAILED.

We can't avoid scheduling dad_work for addresses with NODAD but we can
avoid adding TENTATIVE flag to avoid this racy situation.
Signed-off-by: NMahesh Bandewar <maheshb@google.com>
Acked-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Current memset is using incorrect type of variable, causing the
upper-half of the strucutre to be left uninitialized and causing:

  ethernet/qlogic/qed/qed_init_fw_funcs.c: In function 'qed_set_rfs_mode_disable':
  ethernet/qlogic/qed/qed_init_fw_funcs.c:993:3: error: '*((void *)&ramline+4)' is used uninitialized in this function [-Werror=uninitialized]

Fixes: d51e4af5 ("qed: aRFS infrastructure support")
Reported-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NYuval Mintz <Yuval.Mintz@cavium.com>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Device node iterators put the previous value of the index variable, so an
explicit put causes a double put.

In particular, of_mdiobus_register can fail before doing anything
interesting, so one could view it as a no-op from the reference count
point of view.

Generated by: scripts/coccinelle/iterators/device_node_continue.cocci

CC: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: NJulia Lawall <julia.lawall@lip6.fr>
Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When using a TX ring buffer, if an error occurs processing a control
message (e.g. invalid message), the net_device reference is not
released.

Fixes c14ac945 ("sock: enable timestamping using control messages")
Signed-off-by: NDouglas Caetano dos Santos <douglascs@taghos.com.br>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NYuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Macvlan always turns on offload features that have sofware
fallback (NETIF_GSO_SOFTWARE).  This allows much higher guest-guest
communications over macvtap.

However, macvtap does not turn on these features for vlan tagged traffic.
As a result, depending on the HW that mactap is configured on, the
performance of guest-guest communication over a vlan is very
inconsistent.  If the HW supports TSO/UFO over vlans, then the
performance will be fine.  If not, the the performance will suffer
greatly since the VM may continue using TSO/UFO, and will force the host
segment the traffic and possibly overlow the macvtap queue.

This patch adds the always on offloads to vlan_features.  This
makes sure that any vlan tagged traffic between 2 guest will not
be segmented needlessly.
Signed-off-by: NVladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There are two pointers in sysfs_display_ring,
one that increments if using normal dma descriptors,
another if using extended dma descriptors.

When printing the normal dma descriptors, the wrong pointer is used,
thus the printed descriptor addresses are incorrect.
Signed-off-by: NNiklas Cassel <niklas.cassel@axis.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The feature member of virtio_feature_desc contains little endian
values, given that it contents will be converted with
le32_to_cpu(). The "wrong" __u32 type leads to the sparse warnings
below.
In order to avoid them, use the correct __le32 type instead.

drivers/s390/virtio/virtio_ccw.c:749:14: warning: cast to restricted __le32
drivers/s390/virtio/virtio_ccw.c:762:28: warning: cast to restricted __le32
Acked-by: NHalil Pasic <pasic@linux.vnet.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Root flow table is dynamically changed by the underlying flow steering
layer, and IPoIB/ULPs have no idea what will be the root flow table in
the future, hence we need a dynamic infrastructure to move Underlay QPs
with the root flow table.

Fixes: b3ba5149 ("net/mlx5: Refactor create flow table method to accept underlay QP")
Signed-off-by: NErez Shitrit <erezsh@mellanox.com>
Signed-off-by: NMaor Gottlieb <maorg@mellanox.com>
Signed-off-by: NYishai Hadas <yishaih@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

IPoIB doesn't support striding RQ at the moment, for this
we need to explicitly choose non striding RQ in IPoIB init,
even if the HW supports it.

Fixes: 8f493ffd ("net/mlx5e: IPoIB, RX steering RSS RQTs and TIRs")
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Fail-safe support patches introduced a trivial bug,
setup tc callback is doing a wrong check of the netdevice state,
the fix is simply to invert the condition.

Fixes: 6f9485af ("net/mlx5e: Fail safe tc setup")
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Pause bit should set when RX pause is on, not TX pause.
Also, setting Asym_Pause is incorrect, and should be turned off.

Fixes: 665bc539 ("net/mlx5e: Use new ethtool get/set link ksettings API")
Signed-off-by: NGal Pressman <galp@mellanox.com>
Cc: kernel-team@fb.com
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Query the operational pause from firmware (PFCC register) instead of
always passing zeros.

Fixes: 665bc539 ("net/mlx5e: Use new ethtool get/set link ksettings API")
Signed-off-by: NGal Pressman <galp@mellanox.com>
Cc: kernel-team@fb.com
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Pull some more input subsystem updates from Dmitry Torokhov:
 "An updated xpad driver with a few more recognized device IDs, and a
  new psxpad-spi driver, allowing connecting Playstation 1 and 2 joypads
  via SPI bus"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: cros_ec_keyb - remove extraneous 'const'
  Input: add support for PlayStation 1/2 joypads connected via SPI
  Input: xpad - add USB IDs for Mad Catz Brawlstick and Razer Sabertooth
  Input: xpad - sync supported devices with xboxdrv
  Input: xpad - sort supported devices by USB ID

Pull UBI/UBIFS updates from Richard Weinberger:

 - new config option CONFIG_UBIFS_FS_SECURITY

 - minor improvements

 - random fixes

* tag 'upstream-4.12-rc1' of git://git.infradead.org/linux-ubifs:
  ubi: Add debugfs file for tracking PEB state
  ubifs: Fix a typo in comment of ioctl2ubifs & ubifs2ioctl
  ubifs: Remove unnecessary assignment
  ubifs: Fix cut and paste error on sb type comparisons
  ubi: fastmap: Fix slab corruption
  ubifs: Add CONFIG_UBIFS_FS_SECURITY to disable/enable security labels
  ubi: Make mtd parameter readable
  ubi: Fix section mismatch

Pull UML fixes from Richard Weinberger:
 "No new stuff, just fixes"

* 'for-linus-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: Add missing NR_CPUS include
  um: Fix to call read_initrd after init_bootmem
  um: Include kbuild.h instead of duplicating its macros
  um: Fix PTRACE_POKEUSER on x86_64
  um: Set number of CPUs
  um: Fix _print_addr()

Merge misc fixes from Andrew Morton:
 "15 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm, docs: update memory.stat description with workingset* entries
  mm: vmscan: scan until it finds eligible pages
  mm, thp: copying user pages must schedule on collapse
  dax: fix PMD data corruption when fault races with write
  dax: fix data corruption when fault races with write
  ext4: return to starting transaction in ext4_dax_huge_fault()
  mm: fix data corruption due to stale mmap reads
  dax: prevent invalidation of mapped DAX entries
  Tigran has moved
  mm, vmalloc: fix vmalloc users tracking properly
  mm/khugepaged: add missed tracepoint for collapse_huge_page_swapin
  gcov: support GCC 7.1
  mm, vmstat: Remove spurious WARN() during zoneinfo print
  time: delete current_fs_time()
  hwpoison, memcg: forcibly uncharge LRU pages

Some minor cleanup of cifs query xattr functions (will also make
SMB3 xattr implementation cleaner as well).
Signed-off-by: NSteve French <steve.french@primarydata.com>

Use time_after kernel macro for time comparison
that has safety check.
Signed-off-by: NKarim Eshapa <karim.eshapa@gmail.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

In fs/cifs/smb2pdu.h, we have:
#define SMB2_SHARE_TYPE_DISK    0x01
#define SMB2_SHARE_TYPE_PIPE    0x02
#define SMB2_SHARE_TYPE_PRINT   0x03

Knowing that, with the current code, the SMB2_SHARE_TYPE_PRINT case can
never trigger and printer share would be interpreted as disk share.

So, test the ShareType value for equality instead.

Fixes: faaf946a ("CIFS: Add tree connect/disconnect capability for SMB2")
Signed-off-by: NChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

Create an ops variable to store tcon->ses->server->ops and cache
indirections and reduce code size a trivial bit.

$ size fs/cifs/cifsacl.o*
   text	   data	    bss	    dec	    hex	filename
   5338	    136	      8	   5482	   156a	fs/cifs/cifsacl.o.new
   5371	    136	      8	   5515	   158b	fs/cifs/cifsacl.o.old
Signed-off-by: NJoe Perches <joe@perches.com>
Acked-by: NShirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

Commit 4b4cea91691d ("mm: vmscan: fix IO/refault regression in cache
workingset transition") introduced three new entries in memory stat
file:

 - workingset_refault
 - workingset_activate
 - workingset_nodereclaim

This commit adds a corresponding description to the cgroup v2 docs.

Link: http://lkml.kernel.org/r/1494530293-31236-1-git-send-email-guro@fb.comSigned-off-by: NRoman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Although there are a ton of free swap and anonymous LRU page in elgible
zones, OOM happened.

  balloon invoked oom-killer: gfp_mask=0x17080c0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOTRACK), nodemask=(null),  order=0, oom_score_adj=0
  CPU: 7 PID: 1138 Comm: balloon Not tainted 4.11.0-rc6-mm1-zram-00289-ge228d67e9677-dirty #17
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
  Call Trace:
   oom_kill_process+0x21d/0x3f0
   out_of_memory+0xd8/0x390
   __alloc_pages_slowpath+0xbc1/0xc50
   __alloc_pages_nodemask+0x1a5/0x1c0
   pte_alloc_one+0x20/0x50
   __pte_alloc+0x1e/0x110
   __handle_mm_fault+0x919/0x960
   handle_mm_fault+0x77/0x120
   __do_page_fault+0x27a/0x550
   trace_do_page_fault+0x43/0x150
   do_async_page_fault+0x2c/0x90
   async_page_fault+0x28/0x30
  Mem-Info:
  active_anon:424716 inactive_anon:65314 isolated_anon:0
   active_file:52 inactive_file:46 isolated_file:0
   unevictable:0 dirty:27 writeback:0 unstable:0
   slab_reclaimable:3967 slab_unreclaimable:4125
   mapped:133 shmem:43 pagetables:1674 bounce:0
   free:4637 free_pcp:225 free_cma:0
  Node 0 active_anon:1698864kB inactive_anon:261256kB active_file:208kB inactive_file:184kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:532kB dirty:108kB writeback:0kB shmem:172kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
  DMA free:7316kB min:32kB low:44kB high:56kB active_anon:8064kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked:0kB slab_reclaimable:464kB slab_unreclaimable:40kB kernel_stack:0kB pagetables:24kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
  lowmem_reserve[]: 0 992 992 1952
  DMA32 free:9088kB min:2048kB low:3064kB high:4080kB active_anon:952176kB inactive_anon:0kB active_file:36kB inactive_file:0kB unevictable:0kB writepending:88kB present:1032192kB managed:1019388kB mlocked:0kB slab_reclaimable:13532kB slab_unreclaimable:16460kB kernel_stack:3552kB pagetables:6672kB bounce:0kB free_pcp:56kB local_pcp:24kB free_cma:0kB
  lowmem_reserve[]: 0 0 0 959
  Movable free:3644kB min:1980kB low:2960kB high:3940kB active_anon:738560kB inactive_anon:261340kB active_file:188kB inactive_file:640kB unevictable:0kB writepending:20kB present:1048444kB managed:1010816kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:832kB local_pcp:60kB free_cma:0kB
  lowmem_reserve[]: 0 0 0 0
  DMA: 1*4kB (E) 0*8kB 18*16kB (E) 10*32kB (E) 10*64kB (E) 9*128kB (ME) 8*256kB (E) 2*512kB (E) 2*1024kB (E) 0*2048kB 0*4096kB = 7524kB
  DMA32: 417*4kB (UMEH) 181*8kB (UMEH) 68*16kB (UMEH) 48*32kB (UMEH) 14*64kB (MH) 3*128kB (M) 1*256kB (H) 1*512kB (M) 2*1024kB (M) 0*2048kB 0*4096kB = 9836kB
  Movable: 1*4kB (M) 1*8kB (M) 1*16kB (M) 1*32kB (M) 0*64kB 1*128kB (M) 2*256kB (M) 4*512kB (M) 1*1024kB (M) 0*2048kB 0*4096kB = 3772kB
  378 total pagecache pages
  17 pages in swap cache
  Swap cache stats: add 17325, delete 17302, find 0/27
  Free swap  = 978940kB
  Total swap = 1048572kB
  524157 pages RAM
  0 pages HighMem/MovableOnly
  12629 pages reserved
  0 pages cma reserved
  0 pages hwpoisoned
  [ pid ]   uid  tgid total_vm      rss nr_ptes nr_pmds swapents oom_score_adj name
  [  433]     0   433     4904        5      14       3       82             0 upstart-udev-br
  [  438]     0   438    12371        5      27       3      191         -1000 systemd-udevd

With investigation, skipping page of isolate_lru_pages makes reclaim
void because it returns zero nr_taken easily so LRU shrinking is
effectively nothing and just increases priority aggressively.  Finally,
OOM happens.

The problem is that get_scan_count determines nr_to_scan with eligible
zones so although priority drops to zero, it couldn't reclaim any pages
if the LRU contains mostly ineligible pages.

get_scan_count:

        size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
	size = size >> sc->priority;

Assumes sc->priority is 0 and LRU list is as follows.

	N-N-N-N-H-H-H-H-H-H-H-H-H-H-H-H-H-H-H-H

(Ie, small eligible pages are in the head of LRU but others are
 almost ineligible pages)

In that case, size becomes 4 so VM want to scan 4 pages but 4 pages from
tail of the LRU are not eligible pages.  If get_scan_count counts
skipped pages, it doesn't reclaim any pages remained after scanning 4
pages so it ends up OOM happening.

This patch makes isolate_lru_pages try to scan pages until it encounters
eligible zones's pages.

[akpm@linux-foundation.org: clean up mind-bending `for' statement.  Tweak comment text]
Fixes: 3db65812 ("Revert "mm, vmscan: account for skipped pages as a partial scan"")
Link: http://lkml.kernel.org/r/1494457232-27401-1-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We have encountered need_resched warnings in __collapse_huge_page_copy()
while doing {clear,copy}_user_highpage() over HPAGE_PMD_NR source pages.

mm->mmap_sem is held for write, but the iteration is well bounded.

Reschedule as needed.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1705101426380.109808@chino.kir.corp.google.comSigned-off-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>