This patch tries to implement an device IOTLB for vhost. This could be
used with userspace(qemu) implementation of DMA remapping
to emulate an IOMMU for the guest.

The idea is simple, cache the translation in a software device IOTLB
(which is implemented as an interval tree) in vhost and use vhost_net
file descriptor for reporting IOTLB miss and IOTLB
update/invalidation. When vhost meets an IOTLB miss, the fault
address, size and access can be read from the file. After userspace
finishes the translation, it writes the translated address to the
vhost_net file to update the device IOTLB.

When device IOTLB is enabled by setting VIRTIO_F_IOMMU_PLATFORM all vq
addresses set by ioctl are treated as iova instead of virtual address and
the accessing can only be done through IOTLB instead of direct userspace
memory access. Before each round or vq processing, all vq metadata is
prefetched in device IOTLB to make sure no translation fault happens
during vq processing.

In most cases, virtqueues are contiguous even in virtual address space.
The IOTLB translation for virtqueue itself may make it a little
slower. We might add fast path cache on top of this patch.
Signed-off-by: Jason Wang <jasowang@redhat.com>
[mst: use virtio feature bit: VHOST_F_DEVICE_IOTLB -> VIRTIO_F_IOMMU_PLATFORM ]
[mst: fix build warnings ]
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
[ weiyj.lk: missing unlock on error ]
Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>

vringh isn't used by vhost net or scsi - it's used
by CAIF only at the moment. Drop the dependency.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Current pre-sorted memory region array has some limitations for future
device IOTLB conversion:

1) need extra work for adding and removing a single region, and it's
   expected to be slow because of sorting or memory re-allocation.
2) need extra work of removing a large range which may intersect
   several regions with different size.
3) need trick for a replacement policy like LRU

To overcome the above shortcomings, this patch convert it to interval
tree which can easily address the above issue with almost no extra
work.

The patch could be used for:

- Extend the current API and only let the userspace to send diffs of
  memory table.
- Simplify Device IOTLB implementation.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

This patch introduces vhost memory accessors which were just wrappers
for userspace address access helpers. This is a requirement for vhost
device iotlb implementation which will add iotlb translations in those
accessors.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Enable virtio-vsock and vhost-vsock.
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

VM sockets vhost transport implementation.  This driver runs on the
host.
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

VM sockets virtio transport implementation.  This driver runs in the
guest.
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

This module contains the common code and header files for the following
virtio_transporto and vhost_vsock kernel modules.
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

The virtio transport will implement graceful shutdown and the related
SO_LINGER socket option.  This requires orphaning the sock but keeping
it in the table of connections after .release().

This patch adds the vsock_remove_sock() function and leaves it up to the
transport when to remove the sock.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

struct vsock_transport contains function pointers called by AF_VSOCK
core code.  The transport may want its own transport-specific function
pointers and they can be added after struct vsock_transport.

Allow the transport to fetch vsock_transport.  It can downcast it to
access transport-specific function pointers.

The virtio transport will use this.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

vringh isn't used by vhost net or scsi - it's used
by CAIF only at the moment. Drop the dependency.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

VOP selects VHOST_RING. Pull in Kconfig that includes it
to make it self-containing.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

The interaction between virtio and IOMMUs is messy.

On most systems with virtio, physical addresses match bus addresses,
and it doesn't particularly matter which one we use to program
the device.

On some systems, including Xen and any system with a physical device
that speaks virtio behind a physical IOMMU, we must program the IOMMU
for virtio DMA to work at all.

On other systems, including SPARC and PPC64, virtio-pci devices are
enumerated as though they are behind an IOMMU, but the virtio host
ignores the IOMMU, so we must either pretend that the IOMMU isn't
there or somehow map everything as the identity.

Add a feature bit to detect that quirk: VIRTIO_F_IOMMU_PLATFORM.

Any device with this feature bit set to 0 needs a quirk and has to be
passed physical addresses (as opposed to bus addresses) even though
the device is behind an IOMMU.

Note: it has to be a per-device quirk because for example, there could
be a mix of passed-through and virtual virtio devices. As another
example, some devices could be implemented by an out of process
hypervisor backend (in case of qemu vhost, or vhost-user) and so support
for an IOMMU needs to be coded up separately.

It would be cleanest to handle this in IOMMU core code, but that needs
per-device DMA ops. While we are waiting for that to be implemented, use
a work-around in virtio core.

Note: a "noiommu" feature is a quirk - add a wrapper to make
that clear.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

The balloon has a special mechanism that is subscribed to the oom
notification which leads to deflation for a fixed number of pages.
The number is always fixed even when the balloon is fully deflated.
But leak_balloon did not expect that the pages to deflate will be more
than taken, and raise a "BUG" in balloon_page_dequeue when page list
will be empty.

So, the simplest solution would be to check that the number of releases
pages is less or equal to the number taken pages.

Cc: stable@vger.kernel.org
Signed-off-by: Konstantin Neumoin <kneumoin@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

We use spinlock to synchronize the work list now which may cause
unnecessary contentions. So this patch switch to use llist to remove
this contention. Pktgen tests shows about 5% improvement:

Before:
~1300000 pps
After:
~1370000 pps
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

We used to implement the work flushing through tracking queued seq,
done seq, and the number of flushing. This patch simplify this by just
implement work flushing through another kind of vhost work with
completion. This will be used by lockless enqueuing patch.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Pull ceph fix from Ilya Dryomov:
 "A fix for a long-standing bug in the incremental osdmap handling code
  that caused misdirected requests, tagged for stable"

  The tag is signed with a brand new key - Sage is on vacation and I
  didn't anticipate this"

* tag 'ceph-for-4.7-rc8' of git://github.com/ceph/ceph-client:
  libceph: apply new_state before new_up_client on incrementals

Pull networking fixes from David Miller:

 1) Fix memory leak in nftables, from Liping Zhang.

 2) Need to check result of vlan_insert_tag() in batman-adv otherwise we
    risk NULL skb derefs, from Sven Eckelmann.

 3) Check for dev_alloc_skb() failures in cfg80211, from Gregory
    Greenman.

 4) Handle properly when we have ppp_unregister_channel() happening in
    parallel with ppp_connect_channel(), from WANG Cong.

 5) Fix DCCP deadlock, from Eric Dumazet.

 6) Bail out properly in UDP if sk_filter() truncates the packet to be
    smaller than even the space that the protocol headers need.  From
    Michal Kubecek.

 7) Similarly for rose, dccp, and sctp, from Willem de Bruijn.

 8) Make TCP challenge ACKs less predictable, from Eric Dumazet.

 9) Fix infinite loop in bgmac_dma_tx_add() from Florian Fainelli.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (65 commits)
  packet: propagate sock_cmsg_send() error
  net/mlx5e: Fix del vxlan port command buffer memset
  packet: fix second argument of sock_tx_timestamp()
  net: switchdev: change ageing_time type to clock_t
  Update maintainer for EHEA driver.
  net/mlx4_en: Add resilience in low memory systems
  net/mlx4_en: Move filters cleanup to a proper location
  sctp: load transport header after sk_filter
  net/sched/sch_htb: clamp xstats tokens to fit into 32-bit int
  net: cavium: liquidio: Avoid dma_unmap_single on uninitialized ndata
  net: nb8800: Fix SKB leak in nb8800_receive()
  et131x: Fix logical vs bitwise check in et131x_tx_timeout()
  vlan: use a valid default mtu value for vlan over macsec
  net: bgmac: Fix infinite loop in bgmac_dma_tx_add()
  mlxsw: spectrum: Prevent invalid ingress buffer mapping
  mlxsw: spectrum: Prevent overwrite of DCB capability fields
  mlxsw: spectrum: Don't emit errors when PFC is disabled
  mlxsw: spectrum: Indicate support for autonegotiation
  mlxsw: spectrum: Force link training according to admin state
  r8152: add MODULE_VERSION
  ...

Pull overlayfs fixes from Miklos Szeredi:
 "This contains a fix for a potential crash/corruption issue and another
  where the suid/sgid bits weren't cleared on write"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: verify upper dentry in ovl_remove_and_whiteout()
  ovl: Copy up underlying inode's ->i_mode to overlay inode
  ovl: handle ATTR_KILL*

Merge misc fixes from Andrew Morton:
 "Five fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  pps: do not crash when failed to register
  tools/vm/slabinfo: fix an unintentional printf
  testing/radix-tree: fix a macro expansion bug
  radix-tree: fix radix_tree_iter_retry() for tagged iterators.
  mm: memcontrol: fix cgroup creation failure after many small jobs

Pull intel kabylake drm fixes from Dave Airlie:
 "As mentioned Intel has gathered all the Kabylake fixes from -next,
  which we've enabled in 4.7 for the first time, these are pretty much
  limited in scope to only affects kabylake, which is hw that isn't
  shipping yet.  So I'm mostly okay with it going in now.

  If we don't land this, it might be a good idea to disable kabylake
  support in 4.7 before we ship"

* tag 'drm-fixes-for-v4.7-rc8-intel-kbl' of git://people.freedesktop.org/~airlied/linux: (28 commits)
  drm/i915/kbl: Introduce the first official DMC for Kabylake.
  drm/i915: Introduce Kabypoint PCH for Kabylake H/DT.
  drm/i915/gen9: implement WaConextSwitchWithConcurrentTLBInvalidate
  drm/i915/gen9: Add WaFbcHighMemBwCorruptionAvoidance
  drm/i195/fbc: Add WaFbcNukeOnHostModify
  drm/i915/gen9: Add WaFbcWakeMemOn
  drm/i915/gen9: Add WaFbcTurnOffFbcWatermark
  drm/i915/kbl: Add WaClearSlmSpaceAtContextSwitch
  drm/i915/gen9: Add WaEnableChickenDCPR
  drm/i915/kbl: Add WaDisableSbeCacheDispatchPortSharing
  drm/i915/kbl: Add WaDisableGafsUnitClkGating
  drm/i915/kbl: Add WaForGAMHang
  drm/i915: Add WaInsertDummyPushConstP for bxt and kbl
  drm/i915/kbl: Add WaDisableDynamicCreditSharing
  drm/i915/kbl: Add WaDisableGamClockGating
  drm/i915/gen9: Enable must set chicken bits in config0 reg
  drm/i915/kbl: Add WaDisableLSQCROPERFforOCL
  drm/i915/kbl: Add WaDisableSDEUnitClockGating
  drm/i915/kbl: Add WaDisableFenceDestinationToSLM for A0
  drm/i915/kbl: Add WaEnableGapsTsvCreditFix
  ...

Pull drm fixes from Dave Airlie:
 "Two i915 regression fixes.

  Intel have submitted some Kabylake fixes I'll send separately, since
  this is the first kernel with kabylake support and they don't go much
  outside that area I think they should be fine"

* tag 'drm-fixes-for-v4.7-rc8-intel' of git://people.freedesktop.org/~airlied/linux:
  drm/i915: add missing condition for committing planes on crtc
  drm/i915: Treat eDP as always connected, again

Pull m68k upddates from Geert Uytterhoeven:
 - assorted spelling fixes
 - defconfig updates

* tag 'm68k-for-v4.8-tag1' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k:
  m68k/defconfig: Update defconfigs for v4.7-rc2
  m68k: Assorted spelling fixes

Pull ARM SoC fixes from Olof Johansson:
 "A handful of fixes before final release:

  Marvell Armada:
   - One to fix a typo in the devicetree specifying memory ranges for
     the crypto engine
   - Two to deal with marking PCI and device-memory as strongly ordered
     to avoid hardware deadlocks, in particular when enabling above
     crypto driver.
   - Compile fix for PM

  Allwinner:
   - DT clock fixes to deal with u-boot-enabled framebuffer (simplefb).
   - Make R8 (C.H.I.P. SoC) inherit system compatibility from A13 to
     make clocks register proper.

  Tegra:
   - Fix SD card voltage setting on the Tegra3 Beaver dev board

  Misc:
   - Two maintainers updates for STM32 and STi platforms"

* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: tegra: beaver: Allow SD card voltage to be changed
  MAINTAINERS: update STi maintainer list
  MAINTAINERS: update STM32 maintainers list
  ARM: mvebu: compile pm code conditionally
  ARM: dts: sun7i: Fix pll3x2 and pll7x2 not having a parent clock
  ARM: dts: sunxi: Add pll3 to simplefb nodes clocks lists
  ARM: dts: armada-38x: fix MBUS_ID for crypto SRAM on Armada 385 Linksys
  ARM: mvebu: map PCI I/O regions strongly ordered
  ARM: mvebu: fix HW I/O coherency related deadlocks
  ARM: sunxi/dt: make the CHIP inherit from allwinner,sun5i-a13

Pull crypto fixes from Herbert Xu:
 "This fixes a sporadic build failure in the qat driver as well as a
  memory corruption bug in rsa-pkcs1pad"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: rsa-pkcs1pad - fix rsa-pkcs1pad request struct
  crypto: qat - make qat_asym_algs.o depend on asn1 headers

Pull key handling fixes from James Morris:
 "Quoting David Howells:

  Here are three miscellaneous fixes:

  (1) Fix a panic in some debugging code in PKCS#7.  This can only
      happen by explicitly inserting a #define DEBUG into the code.

  (2) Fix the calculation of the digest length in the PE file parser.
      This causes a failure where there should be a success.

  (3) Fix the case where an X.509 cert can be added as an asymmetric key
      to a trusted keyring with no trust restriction if no AKID is
      supplied.

  Bugs (1) and (2) aren't particularly problematic, but (3) allows a
  security check to be bypassed.  Happily, this is a recent regression
  and never made it into a released kernel"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  KEYS: Fix for erroneous trust of incorrectly signed X.509 certs
  pefile: Fix the failure of calculation for digest
  PKCS#7: Fix panic when referring to the empty AKID when DEBUG defined

Pull input fixes from Dmitry Torokhov:
 "A few more fixes for the input subsystem:

   - restore naming for tsc2005 touchscreens as some userspace match on it
   - fix out of bound access in legacy keyboard driver
   - fixup in RMI4 driver

  Everything is tagged for stable as well"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: tsc200x - report proper input_dev name
  tty/vt/keyboard: fix OOB access in do_compute_shiftstate()
  Input: synaptics-rmi4 - fix maximum size check for F12 control register 8

Pull libnvdimm fix from Dan Williams:
 "This contains a regression fix for a problem that was introduced in
  v4.7-rc6.

  In 4.7-rc1 we introduced auto-probing for the ACPI DSM (device-
  specific-method) format that the platform firmware implements for
  nvdimm devices.  We initially fixed a regression in probing the QEMU
  DSM implementation by making acpi_check_dsm() tolerant of the way QEMU
  reports the "0 DSMs supported" condition.

  However, that broke HPE platforms since that tolerance caused the
  driver to mistakenly match the 1-zero-byte response those platforms
  give to "unknown" commands.  Instead, we simply make the driver
  tolerant of not finding any supported DSMs.  This has been tested to
  work with both QEMU and HPE platforms.

  This commit has appeared in a -next release with no reported issues"

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  nfit: make DIMM DSMs optional

Pull GPIO fix from Linus Walleij:
 "Compile problem fix for Tegra,

  Sorry to send this in the last minute but Ingo says this build failure
  is very prominent so I'm not going to wait for v4.7 before sending it.

  It is a case of COMPILE_TEST causing more problems than it solves and
  I'm already swearing about me shooting myself in the foot with that
  gun :("

* tag 'gpio-v4.7-6' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: tegra: don't auto-enable for COMPILE_TEST

Pull clk fixes from Michael Turquette:
 "Fix a bug in the at91 clk driver, two compile time warnings in sunxi
  clk drivers, and one bug in a sunxi clk driver introduced in the 4.7
  merge window"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: at91: fix clk_programmable_set_parent()
  clk: sunxi: remove unused variable
  clk: sunxi: display: Add per-clock flags
  clk: sunxi: tcon-ch1: Do not return a negative error in get_parent

Pull libata fix from Tejun Heo:
 "Another fallout from max_sectors bump a couple years ago.  The lite-on
  optical drive times out on large requests"

* 'for-4.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  libata: LITE-ON CX1-JB256-HP needs lower max_sectors

Pull MMC fixes from Ulf Hansson:
 "Here are a few late mmc fixes intended for v4.7 final.

  MMC core:
   - Fix eMMC packed command header endianness
   - Fix free of uninitialized buffer for mmc ioctl

  MMC host:
   - pxamci: Fix potential oops in ->probe()"

* tag 'mmc-v4.7-rc7' of git://git.linaro.org/people/ulf.hansson/mmc:
  mmc: pxamci: fix potential oops
  mmc: block: fix packed command header endianness
  mmc: block: fix free of uninitialized 'idata->buf'

Pull sound fixes from Takashi Iwai:
 "No surprise, just a few small fixes: a couple of changes are seen in
  the core part, and both of them are rather for unusual error paths.

  The rest are the regular HD-audio fixes and one USB-audio regression
  fix"

* tag 'sound-4.7-fix2' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: usb-audio: Fix quirks code is not called
  ALSA: hda: add AMD Stoney PCI ID with proper driver caps
  ALSA: hda - fix use-after-free after module unload
  ALSA: pcm: Free chmap at PCM free callback, too
  ALSA: ctl: Stop notification after disconnection
  ALSA: hda/realtek - add new pin definition in alc225 pin quirk table

Pull NVMe fix from Jens Axboe:
 "Late addition here, it's basically a revert of a patch that was added
  in this merge window, but has proven to cause problems.

  This is swapping out the RCU based namespace protection with a good
  old mutex instead"

* 'for-linus' of git://git.kernel.dk/linux-block:
  nvme: Remove RCU namespace protection

With this command sequence:

  modprobe plip
  modprobe pps_parport
  rmmod pps_parport

the partport_pps modules causes this crash:

  BUG: unable to handle kernel NULL pointer dereference at (null)
  IP: parport_detach+0x1d/0x60 [pps_parport]
  Oops: 0000 [#1] SMP
  ...
  Call Trace:
    parport_unregister_driver+0x65/0xc0 [parport]
    SyS_delete_module+0x187/0x210

The sequence that builds up to this is:

 1) plip is loaded and takes the parport device for exclusive use:

    plip0: Parallel port at 0x378, using IRQ 7.

 2) pps_parport then fails to grab the device:

    pps_parport: parallel port PPS client
    parport0: cannot grant exclusive access for device pps_parport
    pps_parport: couldn't register with parport0

 3) rmmod of pps_parport is then killed because it tries to access
    pardev->name, but pardev (taken from port->cad) is NULL.

So add a check for NULL in the test there too.

Link: http://lkml.kernel.org/r/20160714115245.12651-1-jslaby@suse.czSigned-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The curly braces are missing here so we print stuff unintentionally.

Fixes: 9da4714a ('slub: slabinfo update for cmpxchg handling')
Link: http://lkml.kernel.org/r/20160715211243.GE19522@mwandaSigned-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There are no parentheses around this macro and it causes a problem when
we do:

	index = rand() % THRASH_SIZE;

Link: http://lkml.kernel.org/r/20160715210953.GC19522@mwandaSigned-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

radix_tree_iter_retry() resets slot to NULL, but it doesn't reset tags.
Then NULL slot and non-zero iter.tags passed to radix_tree_next_slot()
leading to crash:

  RIP: radix_tree_next_slot include/linux/radix-tree.h:473
    find_get_pages_tag+0x334/0x930 mm/filemap.c:1452
  ....
  Call Trace:
    pagevec_lookup_tag+0x3a/0x80 mm/swap.c:960
    mpage_prepare_extent_to_map+0x321/0xa90 fs/ext4/inode.c:2516
    ext4_writepages+0x10be/0x2b20 fs/ext4/inode.c:2736
    do_writepages+0x97/0x100 mm/page-writeback.c:2364
    __filemap_fdatawrite_range+0x248/0x2e0 mm/filemap.c:300
    filemap_write_and_wait_range+0x121/0x1b0 mm/filemap.c:490
    ext4_sync_file+0x34d/0xdb0 fs/ext4/fsync.c:115
    vfs_fsync_range+0x10a/0x250 fs/sync.c:195
    vfs_fsync fs/sync.c:209
    do_fsync+0x42/0x70 fs/sync.c:219
    SYSC_fdatasync fs/sync.c:232
    SyS_fdatasync+0x19/0x20 fs/sync.c:230
    entry_SYSCALL_64_fastpath+0x23/0xc1 arch/x86/entry/entry_64.S:207

We must reset iterator's tags to bail out from radix_tree_next_slot()
and go to the slow-path in radix_tree_next_chunk().

Fixes: 46437f9a ("radix-tree: fix race in gang lookup")
Link: http://lkml.kernel.org/r/1468495196-10604-1-git-send-email-aryabinin@virtuozzo.comSigned-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The memory controller has quite a bit of state that usually outlives the
cgroup and pins its CSS until said state disappears.  At the same time
it imposes a 16-bit limit on the CSS ID space to economically store IDs
in the wild.  Consequently, when we use cgroups to contain frequent but
small and short-lived jobs that leave behind some page cache, we quickly
run into the 64k limitations of outstanding CSSs.  Creating a new cgroup
fails with -ENOSPC while there are only a few, or even no user-visible
cgroups in existence.

Although pinning CSSs past cgroup removal is common, there are only two
instances that actually need an ID after a cgroup is deleted: cache
shadow entries and swapout records.

Cache shadow entries reference the ID weakly and can deal with the CSS
having disappeared when it's looked up later.  They pose no hurdle.

Swap-out records do need to pin the css to hierarchically attribute
swapins after the cgroup has been deleted; though the only pages that
remain swapped out after offlining are tmpfs/shmem pages.  And those
references are under the user's control, so they are manageable.

This patch introduces a private 16-bit memcg ID and switches swap and
cache shadow entries over to using that.  This ID can then be recycled
after offlining when the CSS remains pinned only by objects that don't
specifically need it.

This script demonstrates the problem by faulting one cache page in a new
cgroup and deleting it again:

  set -e
  mkdir -p pages
  for x in `seq 128000`; do
    [ $((x % 1000)) -eq 0 ] && echo $x
    mkdir /cgroup/foo
    echo $$ >/cgroup/foo/cgroup.procs
    echo trex >pages/$x
    echo $$ >/cgroup/cgroup.procs
    rmdir /cgroup/foo
  done

When run on an unpatched kernel, we eventually run out of possible IDs
even though there are no visible cgroups:

  [root@ham ~]# ./cssidstress.sh
  [...]
  65000
  mkdir: cannot create directory '/cgroup/foo': No space left on device

After this patch, the IDs get released upon cgroup destruction and the
cache and css objects get released once memory reclaim kicks in.

[hannes@cmpxchg.org: init the IDR]
  Link: http://lkml.kernel.org/r/20160621154601.GA22431@cmpxchg.org
Fixes: b2052564 ("mm: memcontrol: continue cache reclaim from offlined groups")
Link: http://lkml.kernel.org/r/20160617162516.GD19084@cmpxchg.orgSigned-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: John Garcia <john.garcia@mesosphere.io>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Nikolay Borisov <kernel@kyup.com>
Cc: <stable@vger.kernel.org>	[3.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>