commit 4f612ed3f748962cbef1316ff3d323e2b9055b6e upstream.

We have observed that on very large machines with newer CPUs, the static
key/branch switching delay is on the order of milliseconds.  This is due
to the required broadcast IPIs, which simply does not scale well to
hundreds of CPUs (cores).  If done too frequently, this can adversely
affect tail latencies of various workloads.

One workaround is to increase the sample interval to several seconds,
while decreasing sampled allocation coverage, but the problem still
exists and could still increase tail latencies.

As already noted in the Kconfig help text, there are trade-offs: at
lower sample intervals the dynamic branch results in better performance;
however, at very large sample intervals, the static keys mode can result
in better performance -- careful benchmarking is recommended.

Our initial benchmarking showed that with large enough sample intervals
and workloads stressing the allocator, the static keys mode was slightly
better.  Evaluating and observing the possible system-wide side-effects
of the static-key-switching induced broadcast IPIs, however, was a blind
spot (in particular on large machines with 100s of cores).

Therefore, a major downside of the static keys mode is, unfortunately,
that it is hard to predict performance on new system architectures and
topologies, but also making conclusions about performance of new
workloads based on a limited set of benchmarks.

Most distributions will simply select the defaults, while targeting a
large variety of different workloads and system architectures.  As such,
the better default is CONFIG_KFENCE_STATIC_KEYS=n, and re-enabling it is
only recommended after careful evaluation.

For reference, on x86-64 the condition in kfence_alloc() generates
exactly
2 instructions in the kmem_cache_alloc() fast-path:

 | ...
 | cmpl   $0x0,0x1a8021c(%rip)  # ffffffff82d560d0 <kfence_allocation_gate>
 | je     ffffffff812d6003      <kmem_cache_alloc+0x243>
 | ...

which, given kfence_allocation_gate is infrequently modified, should be
well predicted by most CPUs.

Link: https://lkml.kernel.org/r/20211019102524.2807208-2-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull networking fixes from Jakub Kicinski:
 "Including fixes from WiFi (mac80211), and BPF.

  Current release - regressions:

   - skb_expand_head: adjust skb->truesize to fix socket memory
     accounting

   - mptcp: fix corrupt receiver key in MPC + data + checksum

  Previous releases - regressions:

   - multicast: calculate csum of looped-back and forwarded packets

   - cgroup: fix memory leak caused by missing cgroup_bpf_offline

   - cfg80211: fix management registrations locking, prevent list
     corruption

   - cfg80211: correct false positive in bridge/4addr mode check

   - tcp_bpf: fix race in the tcp_bpf_send_verdict resulting in reusing
     previous verdict

  Previous releases - always broken:

   - sctp: enhancements for the verification tag, prevent attackers from
     killing SCTP sessions

   - tipc: fix size validations for the MSG_CRYPTO type

   - mac80211: mesh: fix HE operation element length check, prevent out
     of bound access

   - tls: fix sign of socket errors, prevent positive error codes being
     reported from read()/write()

   - cfg80211: scan: extend RCU protection in
     cfg80211_add_nontrans_list()

   - implement ->sock_is_readable() for UDP and AF_UNIX, fix poll() for
     sockets in a BPF sockmap

   - bpf: fix potential race in tail call compatibility check resulting
     in two operations which would make the map incompatible succeeding

   - bpf: prevent increasing bpf_jit_limit above max

   - bpf: fix error usage of map_fd and fdget() in generic batch update

   - phy: ethtool: lock the phy for consistency of results

   - prevent infinite while loop in skb_tx_hash() when Tx races with
     driver reconfiguring the queue <> traffic class mapping

   - usbnet: fixes for bad HW conjured by syzbot

   - xen: stop tx queues during live migration, prevent UAF

   - net-sysfs: initialize uid and gid before calling
     net_ns_get_ownership

   - mlxsw: prevent Rx stalls under memory pressure"

* tag 'net-5.15-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (67 commits)
  Revert "net: hns3: fix pause config problem after autoneg disabled"
  mptcp: fix corrupt receiver key in MPC + data + checksum
  riscv, bpf: Fix potential NULL dereference
  octeontx2-af: Fix possible null pointer dereference.
  octeontx2-af: Display all enabled PF VF rsrc_alloc entries.
  octeontx2-af: Check whether ipolicers exists
  net: ethernet: microchip: lan743x: Fix skb allocation failure
  net/tls: Fix flipped sign in async_wait.err assignment
  net/tls: Fix flipped sign in tls_err_abort() calls
  net/smc: Correct spelling mistake to TCPF_SYN_RECV
  net/smc: Fix smc_link->llc_testlink_time overflow
  nfp: bpf: relax prog rejection for mtu check through max_pkt_offset
  vmxnet3: do not stop tx queues after netif_device_detach()
  r8169: Add device 10ec:8162 to driver r8169
  ptp: Document the PTP_CLK_MAGIC ioctl number
  usbnet: fix error return code in usbnet_probe()
  net: hns3: adjust string spaces of some parameters of tx bd info in debugfs
  net: hns3: expand buffer len for some debugfs command
  net: hns3: add more string spaces for dumping packets number of queue info in debugfs
  net: hns3: fix data endian problem of some functions of debugfs
  ...

Add PTP_CLK_MAGIC to the userspace-api/ioctl/ioctl-number.rst
documentation file.

Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20211024163831.10200-1-rdunlap@infradead.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pull pin control fixes from Linus Walleij:
 "Some late pin control fixes, the most generally annoying will probably
  be the AMD IRQ storm fix affecting the Microsoft surface.

  Summary:

   - Three fixes pertaining to Broadcom DT bindings. Some stuff didn't
     work out as inteded, we need to back out

   - A resume bug fix in the STM32 driver

   - Disable and mask the interrupts on probe in the AMD pinctrl driver,
     affecting Microsoft surface"

* tag 'pinctrl-v5.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: amd: disable and mask interrupts on probe
  pinctrl: stm32: use valid pin identifier in stm32_pinctrl_resume()
  Revert "pinctrl: bcm: ns: support updated DT binding as syscon subnode"
  dt-bindings: pinctrl: brcm,ns-pinmux: drop unneeded CRU from example
  Revert "dt-bindings: pinctrl: bcm4708-pinmux: rework binding to use syscon"

Pull networking fixes from Jakub Kicinski:
 "Including fixes from netfilter, and can.

  We'll have one more fix for a socket accounting regression, it's still
  getting polished. Otherwise things look fine.

  Current release - regressions:

   - revert "vrf: reset skb conntrack connection on VRF rcv", there are
     valid uses for previous behavior

   - can: m_can: fix iomap_read_fifo() and iomap_write_fifo()

  Current release - new code bugs:

   - mlx5: e-switch, return correct error code on group creation failure

  Previous releases - regressions:

   - sctp: fix transport encap_port update in sctp_vtag_verify

   - stmmac: fix E2E delay mechanism (in PTP timestamping)

  Previous releases - always broken:

   - netfilter: ip6t_rt: fix out-of-bounds read of ipv6_rt_hdr

   - netfilter: xt_IDLETIMER: fix out-of-bound read caused by lack of
     init

   - netfilter: ipvs: make global sysctl read-only in non-init netns

   - tcp: md5: fix selection between vrf and non-vrf keys

   - ipv6: count rx stats on the orig netdev when forwarding

   - bridge: mcast: use multicast_membership_interval for IGMPv3

   - can:
      - j1939: fix UAF for rx_kref of j1939_priv abort sessions on
        receiving bad messages

      - isotp: fix TX buffer concurrent access in isotp_sendmsg() fix
        return error on FC timeout on TX path

   - ice: fix re-init of RDMA Tx queues and crash if RDMA was not inited

   - hns3: schedule the polling again when allocation fails, prevent
     stalls

   - drivers: add missing of_node_put() when aborting
     for_each_available_child_of_node()

   - ptp: fix possible memory leak and UAF in ptp_clock_register()

   - e1000e: fix packet loss in burst mode on Tiger Lake and later

   - mlx5e: ipsec: fix more checksum offload issues"

* tag 'net-5.15-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (75 commits)
  usbnet: sanity check for maxpacket
  net: enetc: make sure all traffic classes can send large frames
  net: enetc: fix ethtool counter name for PM0_TERR
  ptp: free 'vclock_index' in ptp_clock_release()
  sfc: Don't use netif_info before net_device setup
  sfc: Export fibre-specific supported link modes
  net/mlx5e: IPsec: Fix work queue entry ethernet segment checksum flags
  net/mlx5e: IPsec: Fix a misuse of the software parser's fields
  net/mlx5e: Fix vlan data lost during suspend flow
  net/mlx5: E-switch, Return correct error code on group creation failure
  net/mlx5: Lag, change multipath and bonding to be mutually exclusive
  ice: Add missing E810 device ids
  igc: Update I226_K device ID
  e1000e: Fix packet loss on Tiger Lake and later
  e1000e: Separate TGP board type from SPT
  ptp: Fix possible memory leak in ptp_clock_register()
  net: stmmac: Fix E2E delay mechanism
  nfc: st95hf: Make spi remove() callback return zero
  net: hns3: disable sriov before unload hclge layer
  net: hns3: fix vf reset workqueue cannot exit
  ...

Use the more precise __kernel_sa_family_t for smctp_family, to match
struct sockaddr.

Also, use an unsigned int for the network member; negative networks
don't make much sense. We're already using unsigned for mctp_dev and
mctp_skb_cb, but need to change mctp_sock to suit.

Fixes: 60fc63981693 ("mctp: Add sockaddr_mctp to uapi")
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Acked-by: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull virtio fixes from Michael Tsirkin:
 "Fixes up some issues in rc5"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  vhost-vdpa: Fix the wrong input in config_cb
  VDUSE: fix documentation underline warning
  Revert "virtio-blk: Add validation for block size in config space"
  vhost_vdpa: unset vq irq before freeing irq
  virtio: write back F_VERSION_1 before validate

Tony Nguyen says:

====================
Intel Wired LAN Driver Updates 2021-10-14

Brett ensures RDMA nodes are removed during release and rebuild. He also
corrects fw.mgmt.api to include the patch number for proper
identification.

Dave stops ida_free() being called when an IDA has not been allocated.

Michal corrects the order of parameters being provided and the number of
entries skipped for UDP tunnels.
====================

Link: https://lore.kernel.org/r/20211014181953.3538330-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pull spi fixes from Mark Brown:
 "A few small fixes.

  Mostly driver specific but there's one in the core which fixes a
  deadlock when adding devices on spi-mux that's triggered because
  spi-mux is a SPI device which is itself a SPI controller and so can
  instantiate devices when registered.

  We were using a global lock to protect against reusing chip selects
  but they're a per controller thing so moving the lock per controller
  resolves that"

* tag 'spi-fix-v5.15-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi-mux: Fix false-positive lockdep splats
  spi: Fix deadlock when adding SPI controllers on SPI buses
  spi: bcm-qspi: clear MSPI spifie interrupt during probe
  spi: spi-nxp-fspi: don't depend on a specific node name erratum workaround
  spi: mediatek: skip delays if they are 0
  spi: atmel: Fix PDC transfer setup bug
  spi: spidev: Add SPI ID table
  spi: Use 'flash' node name instead of 'spi-flash' in example

Pull ntfs3 fixes from Konstantin Komarov:
 "Use the new api for mounting as requested by Christoph.

  Also fixed:

   - some memory leaks and panic

   - xfstests (tested on x86_64) generic/016 generic/021 generic/022
     generic/041 generic/274 generic/423

   - some typos, wrong returned error codes, dead code, etc"

* tag 'ntfs3_for_5.15' of git://github.com/Paragon-Software-Group/linux-ntfs3: (70 commits)
  fs/ntfs3: Check for NULL pointers in ni_try_remove_attr_list
  fs/ntfs3: Refactor ntfs_read_mft
  fs/ntfs3: Refactor ni_parse_reparse
  fs/ntfs3: Refactor ntfs_create_inode
  fs/ntfs3: Refactor ntfs_readlink_hlp
  fs/ntfs3: Rework ntfs_utf16_to_nls
  fs/ntfs3: Fix memory leak if fill_super failed
  fs/ntfs3: Keep prealloc for all types of files
  fs/ntfs3: Remove unnecessary functions
  fs/ntfs3: Forbid FALLOC_FL_PUNCH_HOLE for normal files
  fs/ntfs3: Refactoring of ntfs_set_ea
  fs/ntfs3: Remove locked argument in ntfs_set_ea
  fs/ntfs3: Use available posix_acl_release instead of ntfs_posix_acl_release
  fs/ntfs3: Check for NULL if ATTR_EA_INFO is incorrect
  fs/ntfs3: Refactoring of ntfs_init_from_boot
  fs/ntfs3: Reject mount if boot's cluster size < media sector size
  fs/ntfs3: Refactoring lock in ntfs_init_acl
  fs/ntfs3: Change posix_acl_equiv_mode to posix_acl_update_mode
  fs/ntfs3: Pass flags to ntfs_set_ea in ntfs_set_acl_ex
  fs/ntfs3: Refactor ntfs_get_acl_ex for better readability
  ...