With @logbuf_lock removed, the high level printk functions for
storing messages are lockless. Messages can be stored from any
context, so there is no need for the NMI and safe buffers anymore.
Remove the NMI and safe buffers.

Although the safe buffers are removed, the NMI and safe context
tracking is still in place. In these contexts, store the message
immediately but still use irq_work to defer the console printing.

Since printk recursion tracking is in place, safe context tracking
for most of printk is not needed. Remove it. Only safe context
tracking relating to the console and console_owner locks is left
in place. This is because the console and console_owner locks are
needed for the actual printing.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210715193359.25946-4-john.ogness@linutronix.de

Currently the printk safe buffers provide a form of recursion
protection by redirecting to the safe buffers whenever printk() is
recursively called.

In preparation for removal of the safe buffers, provide an alternate
explicit recursion protection. Recursion is limited to 3 levels
per-CPU and per-context.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210715193359.25946-3-john.ogness@linutronix.de

Currently the nmi_backtrace is serialized against other CPUs because
the messages are sent to the NMI buffers. Once these buffers are
removed, only the dumped stack will be serialized against other CPUs
(via the printk_cpu_lock).

Also serialize the nmi_backtrace banner and regs using the
printk_cpu_lock so that per-CPU serialization will be preserved even
after the NMI buffers are removed.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210715193359.25946-2-john.ogness@linutronix.de

Merge misc updates from Andrew Morton:
 "191 patches.

  Subsystems affected by this patch series: kthread, ia64, scripts,
  ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
  slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
  mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
  pagealloc, and memory-failure)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (191 commits)
  mm,hwpoison: make get_hwpoison_page() call get_any_page()
  mm,hwpoison: send SIGBUS with error virutal address
  mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes
  mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
  mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
  mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
  docs: remove description of DISCONTIGMEM
  arch, mm: remove stale mentions of DISCONIGMEM
  mm: remove CONFIG_DISCONTIGMEM
  m68k: remove support for DISCONTIGMEM
  arc: remove support for DISCONTIGMEM
  arc: update comment about HIGHMEM implementation
  alpha: remove DISCONTIGMEM and NUMA
  mm/page_alloc: move free_the_page
  mm/page_alloc: fix counting of managed_pages
  mm/page_alloc: improve memmap_pages dbg msg
  mm: drop SECTION_SHIFT in code comments
  mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
  mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
  mm/page_alloc: scale the number of pages that are batch freed
  ...

Pull device properties framework updates from Rafael Wysocki:
 "These unify device properties access in some pieces of code and make
  related changes.

  Specifics:

   - Handle device properties with software node API in the ACPI IORT
     table parsing code (Heikki Krogerus).

   - Unify of_node access in the common device properties code, constify
     the acpi_dma_supported() argument pointer and fix up CONFIG_ACPI=n
     stubs of some functions related to device properties (Andy
     Shevchenko)"

* tag 'devprop-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  device property: Unify access to of_node
  ACPI: scan: Constify acpi_dma_supported() helper function
  ACPI: property: Constify stubs for CONFIG_ACPI=n case
  ACPI: IORT: Handle device properties with software node API
  device property: Retrieve fwnode from of_node via accessor

Pull PNP updates from Rafael Wysocki:
 "These get rid of unnecessary local variables and function, reduce code
  duplication and clean up message printing.

  Specifics:

   - Remove unnecessary local variables from isapnp_proc_attach_device()
     (Anupama K Patil).

   - Make the callers of pnp_alloc() use kzalloc() directly and drop the
     former (Heiner Kallweit).

   - Make two pieces of code use dev_dbg() instead of dev_printk() with
     the KERN_DEBUG message level (Heiner Kallweit).

   - Use DEVICE_ATTR_RO() instead of full DEVICE_ATTR() in some places
     in card.c (Zhen Lei).

   - Use list_for_each_entry() instead of list_for_each() in
     insert_device() (Zou Wei)"

* tag 'pnp-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PNP: pnpbios: Use list_for_each_entry() instead of list_for_each()
  PNP: use DEVICE_ATTR_RO macro
  PNP: Switch over to dev_dbg()
  PNP: Remove pnp_alloc()
  drivers: pnp: isapnp: proc.c: Remove unnecessary local variables

Pull ACPI updates from Rafael Wysocki:
 "These update the ACPICA code in the kernel to the 20210604 upstream
  revision, add preliminary support for the Platform Runtime Mechanism
  (PRM), address issues related to the handling of device dependencies
  in the ACPI device eunmeration code, improve the tracking of ACPI
  power resource states, improve the ACPI support for suspend-to-idle on
  AMD systems, continue the unification of message printing in the ACPI
  code, address assorted issues and clean up the code in a number of
  places.

  Specifics:

   - Update ACPICA code in the kernel to upstrea revision 20210604
     including the following changes:

      - Add defines for the CXL Host Bridge Structureand and add the
        CFMWS structure definition to CEDT (Alison Schofield).
      - iASL: Finish support for the IVRS ACPI table (Bob Moore).
      - iASL: Add support for the SVKL table (Bob Moore).
      - iASL: Add full support for RGRT ACPI table (Bob Moore).
      - iASL: Add support for the BDAT ACPI table (Bob Moore).
      - iASL: add disassembler support for PRMT (Erik Kaneda).
      - Fix memory leak caused by _CID repair function (Erik Kaneda).
      - Add support for PlatformRtMechanism OpRegion (Erik Kaneda).
      - Add PRMT module header to facilitate parsing (Erik Kaneda).
      - Add _PLD panel positions (Fabian Wüthrich).
      - MADT: add Multiprocessor Wakeup Mailbox Structure and the SVKL
        table headers (Kuppuswamy Sathyanarayanan).
      - Use ACPI_FALLTHROUGH (Wei Ming Chen).

   - Add preliminary support for the Platform Runtime Mechanism (PRM) to
     allow the AML interpreter to call PRM functions (Erik Kaneda).

   - Address some issues related to the handling of device dependencies
     reported by _DEP in the ACPI device enumeration code and clean up
     some related pieces of it (Rafael Wysocki).

   - Improve the tracking of states of ACPI power resources (Rafael
     Wysocki).

   - Improve ACPI support for suspend-to-idle on AMD systems (Alex
     Deucher, Mario Limonciello, Pratik Vishwakarma).

   - Continue the unification and cleanup of message printing in the
     ACPI code (Hanjun Guo, Heiner Kallweit).

   - Fix possible buffer overrun issue with the description_show() sysfs
     attribute method (Krzysztof Wilczyński).

   - Improve the acpi_mask_gpe kernel command line parameter handling
     and clean up the core ACPI code related to sysfs (Andy Shevchenko,
     Baokun Li, Clayton Casciato).

   - Postpone bringing devices in the general ACPI PM domain to D0
     during resume from system-wide suspend until they are really needed
     (Dmitry Torokhov).

   - Make the ACPI processor driver fix up C-state latency if not
     ordered (Mario Limonciello).

   - Add support for identifying devices depening on the given one that
     are not its direct descendants with the help of _DEP (Daniel
     Scally).

   - Extend the checks related to ACPI IRQ overrides on x86 in order to
     avoid false-positives (Hui Wang).

   - Add battery DPTF participant for Intel SoCs (Sumeet Pawnikar).

   - Rearrange the ACPI fan driver and device power management code to
     use a common list of device IDs (Rafael Wysocki).

   - Fix clang CFI violation in the ACPI BGRT table parsing code and
     clean it up (Nathan Chancellor).

   - Add GPE-related quirks for some laptops to the EC driver (Chris
     Chiu, Zhang Rui).

   - Make the ACPI PPTT table parsing code populate the cache-id value
     if present in the firmware (James Morse).

   - Remove redundant clearing of context->ret.pointer from
     acpi_run_osc() (Hans de Goede).

   - Add missing acpi_put_table() in acpi_init_fpdt() (Jing Xiangfeng).

   - Make ACPI APEI handle ARM Processor Error CPER records like Memory
     Error ones to avoid user space task lockups (Xiaofei Tan).

   - Stop warning about disabled ACPI in APEI (Jon Hunter).

   - Fix fall-through warning for Clang in the SBSHC driver (Gustavo A.
     R. Silva).

   - Add custom DSDT file as Makefile prerequisite (Richard Fitzgerald).

   - Initialize local variable to avoid garbage being returned (Colin
     Ian King).

   - Simplify assorted pieces of code, address assorted coding style and
     documentation issues and comment typos (Baokun Li, Christophe
     JAILLET, Clayton Casciato, Liu Shixin, Shaokun Zhang, Wei Yongjun,
     Yang Li, Zhen Lei)"

* tag 'acpi-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (97 commits)
  ACPI: PM: postpone bringing devices to D0 unless we need them
  ACPI: tables: Add custom DSDT file as makefile prerequisite
  ACPI: bgrt: Use sysfs_emit
  ACPI: bgrt: Fix CFI violation
  ACPI: EC: trust DSDT GPE for certain HP laptop
  ACPI: scan: Simplify acpi_table_events_fn()
  ACPI: PM: Adjust behavior for field problems on AMD systems
  ACPI: PM: s2idle: Add support for new Microsoft UUID
  ACPI: PM: s2idle: Add support for multiple func mask
  ACPI: PM: s2idle: Refactor common code
  ACPI: PM: s2idle: Use correct revision id
  ACPI: sysfs: Remove tailing return statement in void function
  ACPI: sysfs: Use __ATTR_RO() and __ATTR_RW() macros
  ACPI: sysfs: Sort headers alphabetically
  ACPI: sysfs: Refactor param_get_trace_state() to drop dead code
  ACPI: sysfs: Unify pattern of memory allocations
  ACPI: sysfs: Allow bitmap list to be supplied to acpi_mask_gpe
  ACPI: sysfs: Make sparse happy about address space in use
  ACPI: scan: Fix race related to dropping dependencies
  ACPI: scan: Reorganize acpi_device_add()
  ...

Pull power management updates from Rafael Wysocki:
 "These add hybrid processors support to the intel_pstate driver and
  make it work with more processor models when HWP is disabled, make the
  intel_idle driver use special C6 idle state paremeters when package
  C-states are disabled, add cooling support to the tegra30 devfreq
  driver, rework the TEO (timer events oriented) cpuidle governor,
  extend the OPP (operating performance points) framework to use the
  required-opps DT property in more cases, fix some issues and clean up
  a number of assorted pieces of code.

  Specifics:

   - Make intel_pstate support hybrid processors using abstract
     performance units in the HWP interface (Rafael Wysocki).

   - Add Icelake servers and Cometlake support in no-HWP mode to
     intel_pstate (Giovanni Gherdovich).

   - Make cpufreq_online() error path be consistent with the CPU device
     removal path in cpufreq (Rafael Wysocki).

   - Clean up 3 cpufreq drivers and the statistics code (Hailong Liu,
     Randy Dunlap, Shaokun Zhang).

   - Make intel_idle use special idle state parameters for C6 when
     package C-states are disabled (Chen Yu).

   - Rework the TEO (timer events oriented) cpuidle governor to address
     some theoretical shortcomings in it (Rafael Wysocki).

   - Drop unneeded semicolon from the TEO governor (Wan Jiabing).

   - Modify the runtime PM framework to accept unassigned suspend and
     resume callback pointers (Ulf Hansson).

   - Improve pm_runtime_get_sync() documentation (Krzysztof Kozlowski).

   - Improve device performance states support in the generic power
     domains (genpd) framework (Ulf Hansson).

   - Fix some documentation issues in genpd (Yang Yingliang).

   - Make the operating performance points (OPP) framework use the
     required-opps DT property in use cases that are not related to
     genpd (Hsin-Yi Wang).

   - Make lazy_link_required_opp_table() use list_del_init instead of
     list_del/INIT_LIST_HEAD (Yang Yingliang).

   - Simplify wake IRQs handling in the core system-wide sleep support
     code and clean up some coding style inconsistencies in it (Tian
     Tao, Zhen Lei).

   - Add cooling support to the tegra30 devfreq driver and improve its
     DT bindings (Dmitry Osipenko).

   - Fix some assorted issues in the devfreq core and drivers (Chanwoo
     Choi, Dong Aisheng, YueHaibing)"

* tag 'pm-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (39 commits)
  PM / devfreq: passive: Fix get_target_freq when not using required-opp
  cpufreq: Make cpufreq_online() call driver->offline() on errors
  opp: Allow required-opps to be used for non genpd use cases
  cpuidle: teo: remove unneeded semicolon in teo_select()
  dt-bindings: devfreq: tegra30-actmon: Add cooling-cells
  dt-bindings: devfreq: tegra30-actmon: Convert to schema
  PM / devfreq: userspace: Use DEVICE_ATTR_RW macro
  PM: runtime: Clarify documentation when callbacks are unassigned
  PM: runtime: Allow unassigned ->runtime_suspend|resume callbacks
  PM: runtime: Improve path in rpm_idle() when no callback
  PM: hibernate: remove leading spaces before tabs
  PM: sleep: remove trailing spaces and tabs
  PM: domains: Drop/restore performance state votes for devices at runtime PM
  PM: domains: Return early if perf state is already set for the device
  PM: domains: Split code in dev_pm_genpd_set_performance_state()
  cpuidle: teo: Use kerneldoc documentation in admin-guide
  cpuidle: teo: Rework most recent idle duration values treatment
  cpuidle: teo: Change the main idle state selection logic
  cpuidle: teo: Cosmetic modification of teo_select()
  cpuidle: teo: Cosmetic modifications of teo_update()
  ...

Pull x86 entry code related updates from Thomas Gleixner:

 - Consolidate the macros for .byte ... opcode sequences

 - Deduplicate register offset defines in include files

 - Simplify the ia32,x32 compat handling of the related syscall tables
   to get rid of #ifdeffery.

 - Clear all EFLAGS which are not required for syscall handling

 - Consolidate the syscall tables and switch the generation over to the
   generic shell script and remove the CFLAGS tweaks which are not
   longer required.

 - Use 'int' type for system call numbers to match the generic code.

 - Add more selftests for syscalls

* tag 'x86-entry-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/syscalls: Don't adjust CFLAGS for syscall tables
  x86/syscalls: Remove -Wno-override-init for syscall tables
  x86/uml/syscalls: Remove array index from syscall initializers
  x86/syscalls: Clear 'offset' and 'prefix' in case they are set in env
  x86/entry: Use int everywhere for system call numbers
  x86/entry: Treat out of range and gap system calls the same
  x86/entry/64: Sign-extend system calls on entry to int
  selftests/x86/syscall: Add tests under ptrace to syscall_numbering_64
  selftests/x86/syscall: Simplify message reporting in syscall_numbering
  selftests/x86/syscall: Update and extend syscall_numbering_64
  x86/syscalls: Switch to generic syscallhdr.sh
  x86/syscalls: Use __NR_syscalls instead of __NR_syscall_max
  x86/unistd: Define X32_NR_syscalls only for 64-bit kernel
  x86/syscalls: Stop filling syscall arrays with *_sys_ni_syscall
  x86/syscalls: Switch to generic syscalltbl.sh
  x86/entry/x32: Rename __x32_compat_sys_* to __x64_compat_sys_*

Pull x86 interrupt related updates from Thomas Gleixner:

 - Consolidate the VECTOR defines and the usage sites.

 - Cleanup GDT/IDT related code and replace open coded ASM with proper
   native helper functions.

* tag 'x86-irq-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kexec: Set_[gi]dt() -> native_[gi]dt_invalidate() in machine_kexec_*.c
  x86: Add native_[ig]dt_invalidate()
  x86/idt: Remove address argument from idt_invalidate()
  x86/irq: Add and use NR_EXTERNAL_VECTORS and NR_SYSTEM_VECTORS
  x86/irq: Remove unused vectors defines

Pull timer updates from Thomas Gleixner:
 "Time and clocksource/clockevent related updates:

  Core changes:

   - Infrastructure to support per CPU "broadcast" devices for per CPU
     clockevent devices which stop in deep idle states. This allows us
     to utilize the more efficient architected timer on certain ARM SoCs
     for normal operation instead of permanentely using the slow to
     access SoC specific clockevent device.

   - Print the name of the broadcast/wakeup device in /proc/timer_list

   - Make the clocksource watchdog more robust against delays between
     reading the current active clocksource and the watchdog
     clocksource. Such delays can be caused by NMIs, SMIs and vCPU
     preemption.

     Handle this by reading the watchdog clocksource twice, i.e. before
     and after reading the current active clocksource. In case that the
     two watchdog reads shows an excessive time delta, the read sequence
     is repeated up to 3 times.

   - Improve the debug output and add a test module for the watchdog
     mechanism.

   - Reimplementation of the venerable time64_to_tm() function with a
     faster and significantly smaller version. Straight from the source,
     i.e. the author of the related research paper contributed this!

  Driver changes:

   - No new drivers, not even new device tree bindings!

   - Fixes, improvements and cleanups and all over the place"

* tag 'timers-core-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
  time/kunit: Add missing MODULE_LICENSE()
  time: Improve performance of time64_to_tm()
  clockevents: Use list_move() instead of list_del()/list_add()
  clocksource: Print deviation in nanoseconds when a clocksource becomes unstable
  clocksource: Provide kernel module to test clocksource watchdog
  clocksource: Reduce clocksource-skew threshold
  clocksource: Limit number of CPUs checked for clock synchronization
  clocksource: Check per-CPU clock synchronization when marked unstable
  clocksource: Retry clock read if long delays detected
  clockevents: Add missing parameter documentation
  clocksource/drivers/timer-ti-dm: Drop unnecessary restore
  clocksource/arm_arch_timer: Improve Allwinner A64 timer workaround
  clocksource/drivers/arm_global_timer: Remove duplicated argument in arm_global_timer
  clocksource/drivers/arm_global_timer: Make symbol 'gt_clk_rate_change_nb' static
  arm: zynq: don't disable CONFIG_ARM_GLOBAL_TIMER due to CONFIG_CPU_FREQ anymore
  clocksource/drivers/arm_global_timer: Implement rate compensation whenever source clock changes
  clocksource/drivers/ingenic: Rename unreasonable array names
  clocksource/drivers/timer-ti-dm: Save and restore timer TIOCP_CFG
  clocksource/drivers/mediatek: Ack and disable interrupts on suspend
  clocksource/drivers/samsung_pwm: Constify source IO memory
  ...

Pull irq updates from Thomas Gleixner:
 "Updates for the interrupt subsystem:

  Core changes:

   - Cleanup and simplification of common code to invoke the low level
     interrupt flow handlers when this invocation requires irqdomain
     resolution. Add the necessary core infrastructure.

   - Provide a proper interface for modular PMU drivers to set the
     interrupt affinity.

   - Add a request flag which allows to exclude interrupts from spurious
     interrupt detection. Useful especially for IPI handlers which
     always return IRQ_HANDLED which turns the spurious interrupt
     detection into a pointless waste of CPU cycles.

  Driver changes:

   - Bulk convert interrupt chip drivers to the new irqdomain low level
     flow handler invocation mechanism.

   - Add device tree bindings for the Renesas R-Car M3-W+ SoC

   - Enable modular build of the Qualcomm PDC driver

   - The usual small fixes and improvements"

* tag 'irq-core-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
  dt-bindings: interrupt-controller: arm,gic-v3: Describe GICv3 optional properties
  irqchip: gic-pm: Remove redundant error log of clock bulk
  irqchip/sun4i: Remove unnecessary oom message
  irqchip/irq-imx-gpcv2: Remove unnecessary oom message
  irqchip/imgpdc: Remove unnecessary oom message
  irqchip/gic-v3-its: Remove unnecessary oom message
  irqchip/gic-v2m: Remove unnecessary oom message
  irqchip/exynos-combiner: Remove unnecessary oom message
  irqchip: Bulk conversion to generic_handle_domain_irq()
  genirq: Move non-irqdomain handle_domain_irq() handling into ARM's handle_IRQ()
  genirq: Add generic_handle_domain_irq() helper
  irqchip/nvic: Convert from handle_IRQ() to handle_domain_irq()
  irqdesc: Fix __handle_domain_irq() comment
  genirq: Use irq_resolve_mapping() to implement __handle_domain_irq() and co
  irqdomain: Introduce irq_resolve_mapping()
  irqdomain: Protect the linear revmap with RCU
  irqdomain: Cache irq_data instead of a virq number in the revmap
  irqdomain: Use struct_size() helper when allocating irqdomain
  irqdomain: Make normal and nomap irqdomains exclusive
  powerpc: Move the use of irq_domain_add_nomap() behind a config option
  ...

Pull CPU hotplug fix from Thomas Gleixner:
 "A fix for the CPU hotplug and cpusets interaction:

  cpusets delegate the hotplug work to a workqueue to prevent a lock
  order inversion vs. the CPU hotplug lock. The work is not flushed
  before the hotplug operation returns which creates user visible
  inconsistent state. Prevent this by flushing the work after dropping
  CPU hotplug lock and before releasing the outer mutex which serializes
  the CPU hotplug related sysfs interface operations"

* tag 'smp-urgent-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Cure the cpusets trainwreck

Pull CPU hotplug cleanup from Thomas Gleixner:
 "A simple cleanup for the CPU hotplug code to avoid per_cpu_ptr()
  reevaluation"

* tag 'smp-core-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Simplify access to percpu cpuhp_state

Pull printk updates from Petr Mladek:

 - Add %pt[RT]s modifier to vsprintf(). It overrides ISO 8601 separator
   by using ' ' (space). It produces "YYYY-mm-dd HH:MM:SS" instead of
   "YYYY-mm-ddTHH:MM:SS".

 - Correctly parse long row of numbers by sscanf() when using the field
   width. Add extensive sscanf() selftest.

 - Generalize re-entrant CPU lock that has already been used to
   serialize dump_stack() output. It is part of the ongoing printk
   rework. It will allow to remove the obsoleted printk_safe buffers and
   introduce atomic consoles.

 - Some code clean up and sparse warning fixes.

* tag 'printk-for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printk: fix cpu lock ordering
  lib/dump_stack: move cpu lock to printk.c
  printk: Remove trailing semicolon in macros
  random32: Fix implicit truncation warning in prandom_seed_state()
  lib: test_scanf: Remove pointless use of type_min() with unsigned types
  selftests: lib: Add wrapper script for test_scanf
  lib: test_scanf: Add tests for sscanf number conversion
  lib: vsprintf: Fix handling of number field widths in vsscanf
  lib: vsprintf: scanf: Negative number must have field width > 1
  usb: host: xhci-tegra: Switch to use %ptTs
  nilfs2: Switch to use %ptTs
  kdb: Switch to use %ptTs
  lib/vsprintf: Allow to override ISO 8601 date and time separator

Merge tag 'hyperv-next-signed-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv updates from Wei Liu:
 "Just a few minor enhancement patches and bug fixes"

* tag 'hyperv-next-signed-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  PCI: hv: Add check for hyperv_initialized in init_hv_pci_drv()
  Drivers: hv: Move Hyper-V extended capability check to arch neutral code
  drivers: hv: Fix missing error code in vmbus_connect()
  x86/hyperv: fix logical processor creation
  hv_utils: Fix passing zero to 'PTR_ERR' warning
  scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs
  Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer
  hv_balloon: Remove redundant assignment to region_start

__get_hwpoison_page() could fail to grab refcount by some race condition,
so it's helpful if we can handle it by retrying.  We already have retry
logic, so make get_hwpoison_page() call get_any_page() when called from
memory_failure().

As a result, get_hwpoison_page() can return negative values (i.e.  error
code), so some callers are also changed to handle error cases.
soft_offline_page() does nothing for -EBUSY because that's enough and
users in userspace can easily handle it.  unpoison_memory() is also
unchanged because it's broken and need thorough fixes (will be done
later).

Link: https://lkml.kernel.org/r/20210603233632.2964832-3-nao.horiguchi@gmail.comSigned-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Now an action required MCE in already hwpoisoned address surely sends a
SIGBUS to current process, but the SIGBUS doesn't convey error virtual
address.  That's not optimal for hwpoison-aware applications.

To fix the issue, make memory_failure() call kill_accessing_process(),
that does pagetable walk to find the error virtual address.  It could find
multiple virtual addresses for the same error page, and it seems hard to
tell which virtual address is correct one.  But that's rare and sending
incorrect virtual address could be better than no address.  So let's
report the first found virtual address for now.

[naoya.horiguchi@nec.com: fix walk_page_range() return]
  Link: https://lkml.kernel.org/r/20210603051055.GA244241@hori.linux.bs1.fc.nec.co.jp

Link: https://lkml.kernel.org/r/20210521030156.2612074-4-nao.horiguchi@gmail.comSigned-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Aili Yao <yaoaili@kingsoft.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jue Wang <juew@google.com>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Dave Hansen reported the following about Feng Tang's tests on a machine
with persistent memory onlined as a DRAM-like device.

  Feng Tang tossed these on a "Cascade Lake" system with 96 threads and
  ~512G of persistent memory and 128G of DRAM.  The PMEM is in "volatile
  use" mode and being managed via the buddy just like the normal RAM.

  The PMEM zones are big ones:

        present  65011712 = 248 G
        high       134595 = 525 M

  The PMEM nodes, of course, don't have any CPUs in them.

  With your series, the pcp->high value per-cpu is 69584 pages or about
  270MB per CPU.  Scaled up by the 96 CPU threads, that's ~26GB of
  worst-case memory in the pcps per zone, or roughly 10% of the size of
  the zone.

This should not cause a problem as such although it could trigger reclaim
due to pages being stored on per-cpu lists for CPUs remote to a node.  It
is not possible to treat cpuless nodes exactly the same as normal nodes
but the worst-case scenario can be mitigated by splitting pcp->high across
all online CPUs for cpuless memory nodes.

Link: https://lkml.kernel.org/r/20210616110743.GK30378@techsingularity.netSuggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Tang, Feng" <feng.tang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The per-cpu page allocator (PCP) only stores order-0 pages.  This means
that all THP and "cheap" high-order allocations including SLUB contends on
the zone->lock.  This patch extends the PCP allocator to store THP and
"cheap" high-order pages.  Note that struct per_cpu_pages increases in
size to 256 bytes (4 cache lines) on x86-64.

Note that this is not necessarily a universal performance win because of
how it is implemented.  High-order pages can cause pcp->high to be
exceeded prematurely for lower-orders so for example, a large number of
THP pages being freed could release order-0 pages from the PCP lists.
Hence, much depends on the allocation/free pattern as observed by a single
CPU to determine if caching helps or hurts a particular workload.

That said, basic performance testing passed.  The following is a netperf
UDP_STREAM test which hits the relevant patches as some of the network
allocations are high-order.

netperf-udp
                                 5.13.0-rc2             5.13.0-rc2
                           mm-pcpburst-v3r4   mm-pcphighorder-v1r7
Hmean     send-64         261.46 (   0.00%)      266.30 *   1.85%*
Hmean     send-128        516.35 (   0.00%)      536.78 *   3.96%*
Hmean     send-256       1014.13 (   0.00%)     1034.63 *   2.02%*
Hmean     send-1024      3907.65 (   0.00%)     4046.11 *   3.54%*
Hmean     send-2048      7492.93 (   0.00%)     7754.85 *   3.50%*
Hmean     send-3312     11410.04 (   0.00%)    11772.32 *   3.18%*
Hmean     send-4096     13521.95 (   0.00%)    13912.34 *   2.89%*
Hmean     send-8192     21660.50 (   0.00%)    22730.72 *   4.94%*
Hmean     send-16384    31902.32 (   0.00%)    32637.50 *   2.30%*

Functionally, a patch like this is necessary to make bulk allocation of
high-order pages work with similar performance to order-0 bulk
allocations.  The bulk allocator is not updated in this series as it would
have to be determined by bulk allocation users how they want to track the
order of pages allocated with the bulk allocator.

Link: https://lkml.kernel.org/r/20210611135753.GC30378@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

After removal of the DISCONTIGMEM memory model the FLAT_NODE_MEM_MAP
configuration option is equivalent to FLATMEM.

Drop CONFIG_FLAT_NODE_MEM_MAP and use CONFIG_FLATMEM instead.

Link: https://lkml.kernel.org/r/20210608091316.3622-10-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

After removal of DISCINTIGMEM the NEED_MULTIPLE_NODES and NUMA
configuration options are equivalent.

Drop CONFIG_NEED_MULTIPLE_NODES and use CONFIG_NUMA instead.

Done with

	$ sed -i 's/CONFIG_NEED_MULTIPLE_NODES/CONFIG_NUMA/' \
		$(git grep -wl CONFIG_NEED_MULTIPLE_NODES)
	$ sed -i 's/NEED_MULTIPLE_NODES/NUMA/' \
		$(git grep -wl NEED_MULTIPLE_NODES)

with manual tweaks afterwards.

[rppt@linux.ibm.com: fix arm boot crash]
  Link: https://lkml.kernel.org/r/YMj9vHhHOiCVN4BF@linux.ibm.com

Link: https://lkml.kernel.org/r/20210608091316.3622-9-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Remove description of DISCONTIGMEM from the "Memory Models" document and
update VM sysctl description so that it won't mention DISCONIGMEM.

Link: https://lkml.kernel.org/r/20210608091316.3622-8-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There are several places that mention DISCONIGMEM in comments or have
stale code guarded by CONFIG_DISCONTIGMEM.

Remove the dead code and update the comments.

Link: https://lkml.kernel.org/r/20210608091316.3622-7-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There are no architectures that support DISCONTIGMEM left.

Remove the configuration option and the dead code it was guarding in the
generic memory management code.

Link: https://lkml.kernel.org/r/20210608091316.3622-6-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

DISCONTIGMEM was replaced by FLATMEM with freeing of the unused memory map
in v5.11.

Remove the support for DISCONTIGMEM entirely.

Link: https://lkml.kernel.org/r/20210608091316.3622-5-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

DISCONTIGMEM was replaced by FLATMEM with freeing of the unused memory map
in v5.11.

Remove the support for DISCONTIGMEM entirely.

Link: https://lkml.kernel.org/r/20210608091316.3622-4-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Arc does not use DISCONTIGMEM to implement high memory, update the comment
describing how high memory works to reflect this.

Link: https://lkml.kernel.org/r/20210608091316.3622-3-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "Remove DISCONTIGMEM memory model", v3.

SPARSEMEM memory model was supposed to entirely replace DISCONTIGMEM a
(long) while ago.  The last architectures that used DISCONTIGMEM were
updated to use other memory models in v5.11 and it is about the time to
entirely remove DISCONTIGMEM from the kernel.

This set removes DISCONTIGMEM from alpha, arc and m68k, simplifies memory
model selection in mm/Kconfig and replaces usage of redundant
CONFIG_NEED_MULTIPLE_NODES and CONFIG_FLAT_NODE_MEM_MAP with CONFIG_NUMA
and CONFIG_FLATMEM respectively.

I've also removed NUMA support on alpha that was BROKEN for more than 15
years.

There were also minor updates all over arch/ to remove mentions of
DISCONTIGMEM in comments and #ifdefs.

This patch (of 9):

NUMA is marked broken on alpha for more than 15 years and DISCONTIGMEM was
replaced with SPARSEMEM in v5.11.

Remove both NUMA and DISCONTIGMEM support from alpha.

Link: https://lkml.kernel.org/r/20210608091316.3622-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20210608091316.3622-2-rppt@kernel.orgSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "Allow high order pages to be stored on PCP", v2.

The per-cpu page allocator (PCP) only handles order-0 pages.  With the
series "Use local_lock for pcp protection and reduce stat overhead" and
"Calculate pcp->high based on zone sizes and active CPUs", it's now
feasible to store high-order pages on PCP lists.

This small series allows PCP to store "cheap" orders where cheap is
determined by PAGE_ALLOC_COSTLY_ORDER and THP-sized allocations.

This patch (of 2):

In the next page, free_compount_page is going to use the common helper
free_the_page.  This patch moves the definition to ease review.  No
functional change.

Link: https://lkml.kernel.org/r/20210603142220.10851-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20210603142220.10851-2-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

commit f6366156 ("mm/page_alloc.c: clear out zone->lowmem_reserve[] if
the zone is empty") clears out zone->lowmem_reserve[] if zone is empty.
But when zone is not empty and sysctl_lowmem_reserve_ratio[i] is set to
zero, zone_managed_pages(zone) is not counted in the managed_pages either.
This is inconsistent with the description of lowmem_reserve, so fix it.

Link: https://lkml.kernel.org/r/20210527125707.3760259-1-liushixin2@huawei.com
Fixes: f6366156 ("mm/page_alloc.c: clear out zone->lowmem_reserve[] if the zone is empty")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reported-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Make debug message more accurate.

Link: https://lkml.kernel.org/r/20210531091908.1738465-6-aisheng.dong@nxp.comSigned-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Actually SECTIONS_SHIFT is used in the kernel code, so the code comments
is strictly incorrect.  And since commit bbeae5b0 ("mm: move page
flags layout to separate header"), SECTIONS_SHIFT definition has been
moved to include/linux/page-flags-layout.h, since code itself looks quite
straighforward, instead of moving the code comment into the new place as
well, we just simply remove it.

This also fixed a checkpatch complain derived from the original code:
WARNING: please, no space before tabs
+ * SECTIONS_SHIFT    ^I^I#bits space required to store a section #$

Link: https://lkml.kernel.org/r/20210531091908.1738465-2-aisheng.dong@nxp.comSigned-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Suggested-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This introduces a new sysctl vm.percpu_pagelist_high_fraction.  It is
similar to the old vm.percpu_pagelist_fraction.  The old sysctl increased
both pcp->batch and pcp->high with the higher pcp->high potentially
reducing zone->lock contention.  However, the higher pcp->batch value also
potentially increased allocation latency while the PCP was refilled.  This
sysctl only adjusts pcp->high so that zone->lock contention is potentially
reduced but allocation latency during a PCP refill remains the same.

  # grep -E "high:|batch" /proc/zoneinfo | tail -2
              high:  649
              batch: 63

  # sysctl vm.percpu_pagelist_high_fraction=8
  # grep -E "high:|batch" /proc/zoneinfo | tail -2
              high:  35071
              batch: 63

  # sysctl vm.percpu_pagelist_high_fraction=64
              high:  4383
              batch: 63

  # sysctl vm.percpu_pagelist_high_fraction=0
              high:  649
              batch: 63

[mgorman@techsingularity.net: fix documentation]
  Link: https://lkml.kernel.org/r/20210528151010.GQ30378@techsingularity.net

Link: https://lkml.kernel.org/r/20210525080119.5455-7-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When kswapd is active then direct reclaim is potentially active.  In
either case, it is possible that a zone would be balanced if pages were
not trapped on PCP lists.  Instead of draining remote pages, simply limit
the size of the PCP lists while kswapd is active.

Link: https://lkml.kernel.org/r/20210525080119.5455-6-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When a task is freeing a large number of order-0 pages, it may acquire the
zone->lock multiple times freeing pages in batches.  This may
unnecessarily contend on the zone lock when freeing very large number of
pages.  This patch adapts the size of the batch based on the recent
pattern to scale the batch size for subsequent frees.

As the machines I used were not large enough to test this are not large
enough to illustrate a problem, a debugging patch shows patterns like the
following (slightly editted for clarity)

Baseline vanilla kernel
  time-unmap-14426   [...] free_pcppages_bulk: free   63 count  378 high  378
  time-unmap-14426   [...] free_pcppages_bulk: free   63 count  378 high  378
  time-unmap-14426   [...] free_pcppages_bulk: free   63 count  378 high  378
  time-unmap-14426   [...] free_pcppages_bulk: free   63 count  378 high  378
  time-unmap-14426   [...] free_pcppages_bulk: free   63 count  378 high  378

With patches
  time-unmap-7724    [...] free_pcppages_bulk: free  126 count  814 high  814
  time-unmap-7724    [...] free_pcppages_bulk: free  252 count  814 high  814
  time-unmap-7724    [...] free_pcppages_bulk: free  504 count  814 high  814
  time-unmap-7724    [...] free_pcppages_bulk: free  751 count  814 high  814
  time-unmap-7724    [...] free_pcppages_bulk: free  751 count  814 high  814

Link: https://lkml.kernel.org/r/20210525080119.5455-5-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The PCP high watermark is based on the number of online CPUs so the
watermarks must be adjusted during CPU hotplug.  At the time of
hot-remove, the number of online CPUs is already adjusted but during
hot-add, a delta needs to be applied to update PCP to the correct value.
After this patch is applied, the high watermarks are adjusted correctly.

  # grep high: /proc/zoneinfo  | tail -1
              high:  649
  # echo 0 > /sys/devices/system/cpu/cpu4/online
  # grep high: /proc/zoneinfo  | tail -1
              high:  664
  # echo 1 > /sys/devices/system/cpu/cpu4/online
  # grep high: /proc/zoneinfo  | tail -1
              high:  649

Link: https://lkml.kernel.org/r/20210525080119.5455-4-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The pcp high watermark is based on the batch size but there is no
relationship between them other than it is convenient to use early in
boot.

This patch takes the first step and bases pcp->high on the zone low
watermark split across the number of CPUs local to a zone while the batch
size remains the same to avoid increasing allocation latencies.  The
intent behind the default pcp->high is "set the number of PCP pages such
that if they are all full that background reclaim is not started
prematurely".

Note that in this patch the pcp->high values are adjusted after memory
hotplug events, min_free_kbytes adjustments and watermark scale factor
adjustments but not CPU hotplug events which is handled later in the
series.

On a test KVM instance;

Before grep -E "high:|batch" /proc/zoneinfo | tail -2
              high:  378
              batch: 63

After grep -E "high:|batch" /proc/zoneinfo | tail -2
              high:  649
              batch: 63

[mgorman@techsingularity.net:  fix __setup_per_zone_wmarks for parallel memory
hotplug]
  Link: https://lkml.kernel.org/r/20210528105925.GN30378@techsingularity.net

Link: https://lkml.kernel.org/r/20210525080119.5455-3-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "Calculate pcp->high based on zone sizes and active CPUs", v2.

The per-cpu page allocator (PCP) is meant to reduce contention on the zone
lock but the sizing of batch and high is archaic and neither takes the
zone size into account or the number of CPUs local to a zone.  With larger
zones and more CPUs per node, the contention is getting worse.
Furthermore, the fact that vm.percpu_pagelist_fraction adjusts both batch
and high values means that the sysctl can reduce zone lock contention but
also increase allocation latencies.

This series disassociates pcp->high from pcp->batch and then scales
pcp->high based on the size of the local zone with limited impact to
reclaim and accounting for active CPUs but leaves pcp->batch static.  It
also adapts the number of pages that can be on the pcp list based on
recent freeing patterns.

The motivation is partially to adjust to larger memory sizes but is also
driven by the fact that large batches of page freeing via release_pages()
often shows zone contention as a major part of the problem.  Another is a
bug report based on an older kernel where a multi-terabyte process can
takes several minutes to exit.  A workaround was to use
vm.percpu_pagelist_fraction to increase the pcp->high value but testing
indicated that a production workload could not use the same values because
of an increase in allocation latencies.  Unfortunately, I cannot reproduce
this test case myself as the multi-terabyte machines are in active use but
it should alleviate the problem.

The series aims to address both and partially acts as a pre-requisite.
pcp only works with order-0 which is useless for SLUB (when using high
orders) and THP (unconditionally).  To store high-order pages on PCP, the
pcp->high values need to be increased first.

This patch (of 6):

The vm.percpu_pagelist_fraction is used to increase the batch and high
limits for the per-cpu page allocator (PCP).  The intent behind the sysctl
is to reduce zone lock acquisition when allocating/freeing pages but it
has a problem.  While it can decrease contention, it can also increase
latency on the allocation side due to unreasonably large batch sizes.
This leads to games where an administrator adjusts
percpu_pagelist_fraction on the fly to work around contention and
allocation latency problems.

This series aims to alleviate the problems with zone lock contention while
avoiding the allocation-side latency problems.  For the purposes of
review, it's easier to remove this sysctl now and reintroduce a similar
sysctl later in the series that deals only with pcp->high.

Link: https://lkml.kernel.org/r/20210525080119.5455-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20210525080119.5455-2-mgorman@techsingularity.netSigned-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

alloc_contig_dump_pages() aims for helping debugging page migration
failure by elevated page refcount compared to expected_count.  (for the
detail, please look at migrate_page_move_mapping)

However, -ENOMEM is just the case that system is under memory pressure
state, not relevant with page refcount at all.  Thus, the dumping page
list is not helpful for the debugging point of view.

Link: https://lkml.kernel.org/r/YKa2Wyo9xqIErpfa@google.comSigned-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: John Dias <joaodias@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>