Since nvmem_unregister() checks for NULL, no need to repeat in
the caller. Drop duplicate NULL checks.
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-13-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Update the example to reflect the new API. I have chosen the brcm-nvram
driver since it seems to be simpler than the qfprom driver.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-12-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Since commit 795ddd18 ("nvmem: core: remove regmap dependency"),
nvmem devices do not use the regmap API. Remove references to it from
the documentation.
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-11-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support for the Security Fuse Processor found on Layerscape SoCs.
This driver implements basic read access.
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-10-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The Security Fuse Processor provides efuses and is responsible for
reading it at SoC startup and configuring it accordingly.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-9-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace unnecessary devm_kstrdup() so to avoid redundant memory allocation.
Suggested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Xiaoke Wang <xkernel.wang@foxmail.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-8-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

D1 has a smaller eFuse block than some other recent SoCs, and it no
longer requires a workaround to read the eFuse data.
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-7-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

D1 has a SID like other Allwinner SoCs, but with a unique eFuse layout.
Add a new compatible string for it.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-6-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch fixes below kernel doc warning,
warning: expecting prototype for qfprom_efuse_reg_write().
Prototype was for qfprom_reg_write() instead

No code changes.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-5-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

nvmem_unregister() frees resources and standard pattern is to allow
caller to not care if it's NULL or not. This will reduce burden on
the callers to perform this check.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-4-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Slightly simplify the devm_nvmem_register() by using the
devm_add_action_or_reset().
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-3-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There are no users and seems no will come of the devm_nvmem_unregister().
Remove the function and remove the unused devm_nvmem_match() along with it.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151527.17216-2-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Merge tag 'fsi-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/joel/fsi into char-misc-next

Joel writes:

FSI changes for v5.18

 * Improvements in SCOM and OCC drivers for error handling and retries

 * Addition of tracepoints for initialisation path

 * API for setting long running SBE FIFO operations

* tag 'fsi-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/joel/fsi:
  fsi: Add trace events in initialization path
  fsi: sbefifo: Implement FSI_SBEFIFO_READ_TIMEOUT_SECONDS ioctl
  fsi: sbefifo: Use specified value of start of response timeout
  fsi: occ: Improve response status checking
  fsi: scom: Remove retries in indirect scoms
  fsi: scom: Fix error handling

Add definitions for trace events to show the scanning flow.
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20220207161640.35605-1-eajames@linux.ibm.comSigned-off-by: Joel Stanley <joel@jms.id.au>

FSI_SBEFIFO_READ_TIMEOUT_SECONDS ioctl sets the read timeout (in
seconds) for the response received by sbefifo device from sbe.  The
timeout affects only the read operation on current sbefifo device fd.

Certain SBE operations can take long time to complete and the default
timeout of 10 seconds might not be sufficient to start receiving
response from SBE.  In such cases, allow the timeout to be set to the
maximum of 120 seconds.

The kernel does not contain the definition of the various SBE
operations, so we must expose an interface to userspace to set the
timeout for the given operation.
Signed-off-by: Amitay Isaacs <amitay@ozlabs.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20220121053816.82253-3-joel@jms.id.auSigned-off-by: Joel Stanley <joel@jms.id.au>

For some of the chip-ops where sbe needs to collect trace information,
sbe can take a long time (>30s) to respond.  Currently these chip-ops
will timeout as the start of response timeout defaults to 10s.

Instead of default value, use specified value.  The require timeout
value will be set using ioctl.
Signed-off-by: Amitay Isaacs <amitay@ozlabs.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20220121053816.82253-2-joel@jms.id.auSigned-off-by: Joel Stanley <joel@jms.id.au>

If the driver sequence number coincidentally equals the previous
command response sequence number, the driver may proceed with
fetching the entire buffer before the OCC has processed the current
command. To be sure the correct response is obtained, check the
command type and also retry if any of the response parameters have
changed when the rest of the buffer is fetched. Also initialize the
driver with a random sequence number in order to reduce the chances
of this happening.
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20220208152235.19686-1-eajames@linux.ibm.comSigned-off-by: Joel Stanley <joel@jms.id.au>

We need the char/misc fixes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Merge tag 'kbuild-fixes-v5.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix the truncated path issue for HAVE_GCC_PLUGINS test in Kconfig

 - Move -Wunsligned-access to W=1 builds to avoid sprinkling warnings
   for the latest Clang

 - Fix missing fclose() in Kconfig

 - Fix Kconfig to touch dep headers correctly when KCONFIG_AUTOCONFIG is
   overridden.

* tag 'kbuild-fixes-v5.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kconfig: fix failing to generate auto.conf
  kconfig: fix missing fclose() on error paths
  Makefile.extrawarn: Move -Wunaligned-access to W=1
  kconfig: let 'shell' return enough output for deep path names

Pull irq fixes from Thomas Gleixner:
 "Interrupt chip driver fixes:

   - Don't install an hotplug notifier for GICV3-ITS on systems which do
     not need it to prevent a warning in the notifier about inconsistent
     state

   - Add the missing device tree matching for the T-HEAD PLIC variant so
     the related SoC is properly supported"

* tag 'irq-urgent-2022-02-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/sifive-plic: Add missing thead,c900-plic match string
  dt-bindings: update riscv plic compatible string
  irqchip/gic-v3-its: Skip HP notifier when no ITS is registered

Pull objtool fix from Borislav Petkov:
 "Fix a case where objtool would mistakenly warn about instructions
  being unreachable"

* tag 'objtool_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/bug: Merge annotate_reachable() into _BUG_FLAGS() asm

Pull scheduler fix from Borislav Petkov:
 "Fix a NULL-ptr dereference when recalculating a sched entity's weight"

* tag 'sched_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix fault in reweight_entity

Pull perf fix from Borislav Petkov:
 "Prevent cgroup event list corruption when switching events"

* tag 'perf_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Fix list corruption in perf_cgroup_switch()

Pull x86 fix from Borislav Petkov:
 "Prevent softlockups when tearing down large SGX enclaves"

* tag 'x86_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sgx: Silence softlockup detection when releasing large enclaves

Pull cifs fixes from Steve French:
 "Three small smb3 reconnect fixes and an error log clarification"

* tag '5.17-rc4-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: mark sessions for reconnection in helper function
  cifs: call helper functions for marking channels for reconnect
  cifs: call cifs_reconnect when a connection is marked
  [smb3] improve error message when mount options conflict with posix

Merge tag 'irqchip-fixes-5.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent

Pull irqchip fixes from Marc Zyngier:

 - Don't register a hotplug notifier on GICv3 systems that advertise
   LPI support, but have no ITS to make use of it

 - Add missing DT matching for the thead,c900-plic variant of the
   SiFive PLIC

Link: https://lore.kernel.org/r/20220211110038.1179155-1-maz@kernel.org

Pull SCSI fixes from James Bottomley:
 "Two minor fixes in the lpfc driver. One changing the classification of
  trace messages and the other fixing a build issue when NVME_FC is
  disabled"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: lpfc: Reduce log messages seen after firmware download
  scsi: lpfc: Remove NVMe support if kernel has NVME_FC disabled

Pull char/misc driver fixes from Greg KH:
 "Here are a small number of char/misc driver fixes for 5.17-rc4 for
  reported issues. They contain:

   - phy driver fixes

   - iio driver fix

   - eeprom driver fix

   - speakup regression fix

   - fastrpc fix

  All of these have been in linux-next with no reported issues"

* tag 'char-misc-5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  iio: buffer: Fix file related error handling in IIO_BUFFER_GET_FD_IOCTL
  speakup-dectlk: Restore pitch setting
  bus: mhi: pci_generic: Add mru_default for Cinterion MV31-W
  bus: mhi: pci_generic: Add mru_default for Foxconn SDX55
  eeprom: ee1004: limit i2c reads to I2C_SMBUS_BLOCK_MAX
  misc: fastrpc: avoid double fput() on failed usercopy
  phy: dphy: Correct clk_pre parameter
  phy: phy-mtk-tphy: Fix duplicated argument in phy-mtk-tphy
  phy: stm32: fix a refcount leak in stm32_usbphyc_pll_enable()
  phy: xilinx: zynqmp: Fix bus width setting for SGMII
  phy: cadence: Sierra: fix error handling bugs in probe()
  phy: ti: Fix missing sentinel for clk_div_table
  phy: broadcom: Kconfig: Fix PHY_BRCM_USB config option
  phy: usb: Leave some clocks running during suspend

Pullstaging driver fixes from Greg KH:
 "Here are two staging driver fixes for 5.17-rc4.  These are:

   - fbtft error path fix

   - vc04_services rcu dereference fix

  Both of these have been in linux-next for a while with no reported
  issues"

* tag 'staging-5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: fbtft: Fix error path in fbtft_driver_module_init()
  staging: vc04_services: Fix RCU dereference check

Pull tty/serial fixes from Greg KH:
 "Here are four small tty/serial fixes for 5.17-rc4.  They are:

   - 8250_pericom change revert to fix a reported regression

   - two speculation fixes for vt_ioctl

   - n_tty regression fix for polling

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  vt_ioctl: add array_index_nospec to VT_ACTIVATE
  vt_ioctl: fix array_index_nospec in vt_setactivate
  serial: 8250_pericom: Revert "Re-enable higher baud rates"
  n_tty: wake up poll(POLLRDNORM) on receiving data

Pull USB fixes from Greg KH:
 "Here are some small USB driver fixes for 5.17-rc4 that resolve some
  reported issues and add new device ids:

   - usb-serial new device ids

   - ulpi cleanup fixes

   - f_fs use-after-free fix

   - dwc3 driver fixes

   - ax88179_178a usb network driver fix

   - usb gadget fixes

  There is a revert at the end of this series to resolve a build problem
  that 0-day found yesterday. Most of these have been in linux-next,
  except for the last few, and all have now passed 0-day tests"

* tag 'usb-5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  Revert "usb: dwc2: drd: fix soft connect when gadget is unconfigured"
  usb: dwc2: drd: fix soft connect when gadget is unconfigured
  usb: gadget: rndis: check size of RNDIS_MSG_SET command
  USB: gadget: validate interface OS descriptor requests
  usb: core: Unregister device on component_add() failure
  net: usb: ax88179_178a: Fix out-of-bounds accesses in RX fixup
  usb: dwc3: gadget: Prevent core from processing stale TRBs
  USB: serial: cp210x: add CPI Bulk Coin Recycler id
  USB: serial: cp210x: add NCR Retail IO box id
  USB: serial: ftdi_sio: add support for Brainboxes US-159/235/320
  usb: gadget: f_uac2: Define specific wTerminalType
  usb: gadget: udc: renesas_usb3: Fix host to USB_ROLE_NONE transition
  usb: raw-gadget: fix handling of dual-direction-capable endpoints
  usb: usb251xb: add boost-up property support
  usb: ulpi: Call of_node_put correctly
  usb: ulpi: Move of_node_put to ulpi_dev_release
  USB: serial: option: add ZTE MF286D modem
  USB: serial: ch341: add support for GW Instek USB2.0-Serial devices
  usb: f_fs: Fix use-after-free for epfile
  usb: dwc3: xilinx: fix uninitialized return value

Pull s390 updates from Vasily Gorbik:
 "Maintainers and reviewers changes:

    - Add Alexander Gordeev as maintainer for s390.

    - Christian Borntraeger will focus on s390 KVM maintainership and
      stays as s390 reviewer.

  Fixes:

   - Fix clang build of modules loader KUnit test.

   - Fix kernel panic in CIO code on FCES path-event when no driver is
     attached to a device or the driver does not provide the path_event
     function"

* tag 's390-5.17-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/cio: verify the driver availability for path_event call
  s390/module: fix building test_modules_helpers.o with clang
  MAINTAINERS: downgrade myself to Reviewer for s390
  MAINTAINERS: add Alexander Gordeev as maintainer for s390

Pull xen fixes from Juergen Gross:

 - Two small cleanups

 - Another fix for addressing the EFI framebuffer above 4GB when running
   as Xen dom0

 - A patch to let Xen guests use reserved bits in MSI- and IO-APIC-
   registers for extended APIC-IDs the same way KVM guests are doing it
   already

* tag 'for-linus-5.17a-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/pci: Make use of the helper macro LIST_HEAD()
  xen/x2apic: Fix inconsistent indenting
  xen/x86: detect support for extended destination ID
  xen/x86: obtain full video frame buffer address for Dom0 also under EFI

Pull seccomp fixes from Kees Cook:
 "This fixes a corner case of fatal SIGSYS being ignored since v5.15.
  Along with the signal fix is a change to seccomp so that seeing
  another syscall after a fatal filter result will cause seccomp to kill
  the process harder.

  Summary:

   - Force HANDLER_EXIT even for SIGNAL_UNKILLABLE

   - Make seccomp self-destruct after fatal filter results

   - Update seccomp samples for easier behavioral demonstration"

* tag 'seccomp-v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  samples/seccomp: Adjust sample to also provide kill option
  seccomp: Invalidate seccomp mode to catch death failures
  signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE

Merge misc fixes from Andrew Morton:
 "5 patches.

  Subsystems affected by this patch series: binfmt, procfs, and mm
  (vmscan, memcg, and kfence)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  kfence: make test case compatible with run time set sample interval
  mm: memcg: synchronize objcg lists with a dedicated spinlock
  mm: vmscan: remove deadlock due to throttling failing to make progress
  fs/proc: task_mmu.c: don't read mapcount for migration entry
  fs/binfmt_elf: fix PT_LOAD p_align values for loaders

When the KCONFIG_AUTOCONFIG is specified (e.g. export \
KCONFIG_AUTOCONFIG=output/config/auto.conf), the directory of
include/config/ will not be created, so kconfig can't create deps
files in it and auto.conf can't be generated.
Signed-off-by: Jing Leng <jleng@ambarella.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

This reverts commit 269cbcf7.

It causes build errors as reported by the kernel test robot.

Link: https://lore.kernel.org/r/202202112236.AwoOTtHO-lkp@intel.comReported-by: kernel test robot <lkp@intel.com>
Fixes: 269cbcf7 ("usb: dwc2: drd: fix soft connect when gadget is unconfigured")
Cc: stable@kernel.org
Cc: Amelie Delaunay <amelie.delaunay@foss.st.com>
Cc: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Cc: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The parameter kfence_sample_interval can be set via boot parameter and
late shell command, which is convenient for automated tests and KFENCE
parameter optimization.  However, KFENCE test case just uses
compile-time CONFIG_KFENCE_SAMPLE_INTERVAL, which will make KFENCE test
case not run as users desired.  Export kfence_sample_interval, so that
KFENCE test case can use run-time-set sample interval.

Link: https://lkml.kernel.org/r/20220207034432.185532-1-liupeng256@huawei.comSigned-off-by: Peng Liu <liupeng256@huawei.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Christian Knig <christian.koenig@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Alexander reported a circular lock dependency revealed by the mmap1 ltp
test:

  LOCKDEP_CIRCULAR (suite: ltp, case: mtest06 (mmap1))
          WARNING: possible circular locking dependency detected
          5.17.0-20220113.rc0.git0.f2211f194038.300.fc35.s390x+debug #1 Not tainted
          ------------------------------------------------------
          mmap1/202299 is trying to acquire lock:
          00000001892c0188 (css_set_lock){..-.}-{2:2}, at: obj_cgroup_release+0x4a/0xe0
          but task is already holding lock:
          00000000ca3b3818 (&sighand->siglock){-.-.}-{2:2}, at: force_sig_info_to_task+0x38/0x180
          which lock already depends on the new lock.
          the existing dependency chain (in reverse order) is:
          -> #1 (&sighand->siglock){-.-.}-{2:2}:
                 __lock_acquire+0x604/0xbd8
                 lock_acquire.part.0+0xe2/0x238
                 lock_acquire+0xb0/0x200
                 _raw_spin_lock_irqsave+0x6a/0xd8
                 __lock_task_sighand+0x90/0x190
                 cgroup_freeze_task+0x2e/0x90
                 cgroup_migrate_execute+0x11c/0x608
                 cgroup_update_dfl_csses+0x246/0x270
                 cgroup_subtree_control_write+0x238/0x518
                 kernfs_fop_write_iter+0x13e/0x1e0
                 new_sync_write+0x100/0x190
                 vfs_write+0x22c/0x2d8
                 ksys_write+0x6c/0xf8
                 __do_syscall+0x1da/0x208
                 system_call+0x82/0xb0
          -> #0 (css_set_lock){..-.}-{2:2}:
                 check_prev_add+0xe0/0xed8
                 validate_chain+0x736/0xb20
                 __lock_acquire+0x604/0xbd8
                 lock_acquire.part.0+0xe2/0x238
                 lock_acquire+0xb0/0x200
                 _raw_spin_lock_irqsave+0x6a/0xd8
                 obj_cgroup_release+0x4a/0xe0
                 percpu_ref_put_many.constprop.0+0x150/0x168
                 drain_obj_stock+0x94/0xe8
                 refill_obj_stock+0x94/0x278
                 obj_cgroup_charge+0x164/0x1d8
                 kmem_cache_alloc+0xac/0x528
                 __sigqueue_alloc+0x150/0x308
                 __send_signal+0x260/0x550
                 send_signal+0x7e/0x348
                 force_sig_info_to_task+0x104/0x180
                 force_sig_fault+0x48/0x58
                 __do_pgm_check+0x120/0x1f0
                 pgm_check_handler+0x11e/0x180
          other info that might help us debug this:
           Possible unsafe locking scenario:
                 CPU0                    CPU1
                 ----                    ----
            lock(&sighand->siglock);
                                         lock(css_set_lock);
                                         lock(&sighand->siglock);
            lock(css_set_lock);
           *** DEADLOCK ***
          2 locks held by mmap1/202299:
           #0: 00000000ca3b3818 (&sighand->siglock){-.-.}-{2:2}, at: force_sig_info_to_task+0x38/0x180
           #1: 00000001892ad560 (rcu_read_lock){....}-{1:2}, at: percpu_ref_put_many.constprop.0+0x0/0x168
          stack backtrace:
          CPU: 15 PID: 202299 Comm: mmap1 Not tainted 5.17.0-20220113.rc0.git0.f2211f194038.300.fc35.s390x+debug #1
          Hardware name: IBM 3906 M04 704 (LPAR)
          Call Trace:
            dump_stack_lvl+0x76/0x98
            check_noncircular+0x136/0x158
            check_prev_add+0xe0/0xed8
            validate_chain+0x736/0xb20
            __lock_acquire+0x604/0xbd8
            lock_acquire.part.0+0xe2/0x238
            lock_acquire+0xb0/0x200
            _raw_spin_lock_irqsave+0x6a/0xd8
            obj_cgroup_release+0x4a/0xe0
            percpu_ref_put_many.constprop.0+0x150/0x168
            drain_obj_stock+0x94/0xe8
            refill_obj_stock+0x94/0x278
            obj_cgroup_charge+0x164/0x1d8
            kmem_cache_alloc+0xac/0x528
            __sigqueue_alloc+0x150/0x308
            __send_signal+0x260/0x550
            send_signal+0x7e/0x348
            force_sig_info_to_task+0x104/0x180
            force_sig_fault+0x48/0x58
            __do_pgm_check+0x120/0x1f0
            pgm_check_handler+0x11e/0x180
          INFO: lockdep is turned off.

In this example a slab allocation from __send_signal() caused a
refilling and draining of a percpu objcg stock, resulted in a releasing
of another non-related objcg.  Objcg release path requires taking the
css_set_lock, which is used to synchronize objcg lists.

This can create a circular dependency with the sighandler lock, which is
taken with the locked css_set_lock by the freezer code (to freeze a
task).

In general it seems that using css_set_lock to synchronize objcg lists
makes any slab allocations and deallocation with the locked css_set_lock
and any intervened locks risky.

To fix the problem and make the code more robust let's stop using
css_set_lock to synchronize objcg lists and use a new dedicated spinlock
instead.

Link: https://lkml.kernel.org/r/Yfm1IHmoGdyUR81T@carbon.dhcp.thefacebook.com
Fixes: bf4f0599 ("mm: memcg/slab: obj_cgroup API")
Signed-off-by: Roman Gushchin <guro@fb.com>
Reported-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Tested-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>