1. 07 Nov, 2021 6 commits
  2. 06 Nov, 2021 34 commits
    • Linus Torvalds's avatar
      Merge tag '5.16-rc-part1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6 · b5013d08
      Linus Torvalds authored
      Pull cifs updates from Steve French:
      
       - reconnect fix for stable
      
       - minor mount option fix
      
       - debugging improvement for (TCP) connection issues
      
       - refactoring of common code to help ksmbd
      
      * tag '5.16-rc-part1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
        smb3: add dynamic trace points for socket connection
        cifs: Move SMB2_Create definitions to the shared area
        cifs: Move more definitions into the shared area
        cifs: move NEGOTIATE_PROTOCOL definitions out into the common area
        cifs: Create a new shared file holding smb2 pdu definitions
        cifs: add mount parameter tcpnodelay
        cifs: To match file servers, make sure the server hostname matches
      b5013d08
    • Linus Torvalds's avatar
      Merge tag 'fsnotify_for_v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs · 2acda754
      Linus Torvalds authored
      Pull fsnotify updates from Jan Kara:
       "Support for reporting filesystem errors through fanotify so that
        system health monitoring daemons can watch for these and act instead
        of scraping system logs"
      
      * tag 'fsnotify_for_v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: (34 commits)
        samples: remove duplicate include in fs-monitor.c
        samples: Fix warning in fsnotify sample
        docs: Fix formatting of literal sections in fanotify docs
        samples: Make fs-monitor depend on libc and headers
        docs: Document the FAN_FS_ERROR event
        samples: Add fs error monitoring example
        ext4: Send notifications on error
        fanotify: Allow users to request FAN_FS_ERROR events
        fanotify: Emit generic error info for error event
        fanotify: Report fid info for file related file system errors
        fanotify: WARN_ON against too large file handles
        fanotify: Add helpers to decide whether to report FID/DFID
        fanotify: Wrap object_fh inline space in a creator macro
        fanotify: Support merging of error events
        fanotify: Support enqueueing of error events
        fanotify: Pre-allocate pool of error events
        fanotify: Reserve UAPI bits for FAN_FS_ERROR
        fsnotify: Support FS_ERROR event type
        fanotify: Require fid_mode for any non-fd event
        fanotify: Encode empty file handle when no inode is provided
        ...
      2acda754
    • Linus Torvalds's avatar
      Merge tag 'fs_for_v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs · d8b4e5bd
      Linus Torvalds authored
      Pull quota, isofs, and reiserfs updates from Jan Kara:
       "Fixes for handling of corrupted quota files, fix for handling of
        corrupted isofs filesystem, and a small cleanup for reiserfs"
      
      * tag 'fs_for_v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
        fs: reiserfs: remove useless new_opts in reiserfs_remount
        isofs: Fix out of bound access for corrupted isofs image
        quota: correct error number in free_dqentry()
        quota: check block number when reading the block in quota file
      d8b4e5bd
    • Linus Torvalds's avatar
      Merge tag 'xtensa-20211105' of git://github.com/jcmvbkbc/linux-xtensa · 00f178e1
      Linus Torvalds authored
      Pull xtensa updates from Max Filippov:
      
       - add support for xtensa cores without windowed registers option
      
      * tag 'xtensa-20211105' of git://github.com/jcmvbkbc/linux-xtensa:
        xtensa: move section symbols to asm/sections.h
        xtensa: remove unused variable wmask
        xtensa: only build windowed register support code when needed
        xtensa: use register window specific opcodes only when present
        xtensa: implement call0 ABI support in assembly
        xtensa: definitions for call0 ABI
        xtensa: don't use a12 in __xtensa_copy_user in call0 ABI
        xtensa: don't use a12 in strncpy_user
        xtensa: use a14 instead of a15 in inline assembly
        xtensa: move _SimulateUserKernelVectorException out of WindowVectors
      00f178e1
    • Linus Torvalds's avatar
      Merge tag 's390-5.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux · 0b707e57
      Linus Torvalds authored
      Pull s390 updates from Vasily Gorbik:
      
       - Add support for ftrace with direct call and ftrace direct call
         samples.
      
       - Add support for kernel command lines longer than current 896 bytes
         and make its length configurable.
      
       - Add support for BEAR enhancement facility to improve last breaking
         event instruction tracking.
      
       - Add kprobes sanity checks and testcases to prevent kprobe in the mid
         of an instruction.
      
       - Allow concurrent access to /dev/hwc for the CPUMF users.
      
       - Various ftrace / jump label improvements.
      
       - Convert unwinder tests to KUnit.
      
       - Add s390_iommu_aperture kernel parameter to tweak the limits on
         concurrently usable DMA mappings.
      
       - Add ap.useirq AP module option which can be used to disable interrupt
         use.
      
       - Add add_disk() error handling support to block device drivers.
      
       - Drop arch specific and use generic implementation of strlcpy and
         strrchr.
      
       - Several __pa/__va usages fixes.
      
       - Various cio, crypto, pci, kernel doc and other small fixes and
         improvements all over the code.
      
      [ Merge fixup as per https://lore.kernel.org/all/YXAqZ%2FEszRisunQw@osiris/ ]
      
      * tag 's390-5.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (63 commits)
        s390: make command line configurable
        s390: support command lines longer than 896 bytes
        s390/kexec_file: move kernel image size check
        s390/pci: add s390_iommu_aperture kernel parameter
        s390/spinlock: remove incorrect kernel doc indicator
        s390/string: use generic strlcpy
        s390/string: use generic strrchr
        s390/ap: function rework based on compiler warning
        s390/cio: make ccw_device_dma_* more robust
        s390/vfio-ap: s390/crypto: fix all kernel-doc warnings
        s390/hmcdrv: fix kernel doc comments
        s390/ap: new module option ap.useirq
        s390/cpumf: Allow multiple processes to access /dev/hwc
        s390/bitops: return true/false (not 1/0) from bool functions
        s390: add support for BEAR enhancement facility
        s390: introduce nospec_uses_trampoline()
        s390: rename last_break to pgm_last_break
        s390/ptrace: add last_break member to pt_regs
        s390/sclp: sort out physical vs virtual pointers usage
        s390/setup: convert start and end initrd pointers to virtual
        ...
      0b707e57
    • Linus Torvalds's avatar
      Merge tag 'pci-v5.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci · 0c5c62dd
      Linus Torvalds authored
      Pull pci updates from Bjorn Helgaas:
       "Enumeration:
         - Conserve IRQs by setting up portdrv IRQs only when there are users
           (Jan Kiszka)
         - Rework and simplify _OSC negotiation for control of PCIe features
           (Joerg Roedel)
         - Remove struct pci_dev.driver pointer since it's redundant with the
           struct device.driver pointer (Uwe Kleine-König)
      
        Resource management:
         - Coalesce contiguous host bridge apertures from _CRS to accommodate
           BARs that cover more than one aperture (Kai-Heng Feng)
      
        Sysfs:
         - Check CAP_SYS_ADMIN before parsing user input (Krzysztof
           Wilczyński)
         - Return -EINVAL consistently from "store" functions (Krzysztof
           Wilczyński)
         - Use sysfs_emit() in endpoint "show" functions to avoid buffer
           overruns (Kunihiko Hayashi)
      
        PCIe native device hotplug:
         - Ignore Link Down/Up caused by resets during error recovery so
           endpoint drivers can remain bound to the device (Lukas Wunner)
      
        Virtualization:
         - Avoid bus resets on Atheros QCA6174, where they hang the device
           (Ingmar Klein)
         - Work around Pericom PI7C9X2G switch packet drop erratum by using
           store and forward mode instead of cut-through (Nathan Rossi)
         - Avoid trying to enable AtomicOps on VFs; the PF setting applies to
           all VFs (Selvin Xavier)
      
        MSI:
         - Document that /sys/bus/pci/devices/.../irq contains the legacy INTx
           interrupt or the IRQ of the first MSI (not MSI-X) vector (Barry
           Song)
      
        VPD:
         - Add pci_read_vpd_any() and pci_write_vpd_any() to access anywhere
           in the possible VPD space; use these to simplify the cxgb3 driver
           (Heiner Kallweit)
      
        Peer-to-peer DMA:
         - Add (not subtract) the bus offset when calculating DMA address
           (Wang Lu)
      
        ASPM:
         - Re-enable LTR at Downstream Ports so they don't report Unsupported
           Requests when reset or hot-added devices send LTR messages
           (Mingchuang Qiao)
      
        Apple PCIe controller driver:
         - Add driver for Apple M1 PCIe controller (Alyssa Rosenzweig, Marc
           Zyngier)
      
        Cadence PCIe controller driver:
         - Return success when probe succeeds instead of falling into error
           path (Li Chen)
      
        HiSilicon Kirin PCIe controller driver:
         - Reorganize PHY logic and add support for external PHY drivers
           (Mauro Carvalho Chehab)
         - Support PERST# GPIOs for HiKey970 external PEX 8606 bridge (Mauro
           Carvalho Chehab)
         - Add Kirin 970 support (Mauro Carvalho Chehab)
         - Make driver removable (Mauro Carvalho Chehab)
      
        Intel VMD host bridge driver:
         - If IOMMU supports interrupt remapping, leave VMD MSI-X remapping
           enabled (Adrian Huang)
         - Number each controller so we can tell them apart in
           /proc/interrupts (Chunguang Xu)
         - Avoid building on UML because VMD depends on x86 bare metal APIs
           (Johannes Berg)
      
        Marvell Aardvark PCIe controller driver:
         - Define macros for PCI_EXP_DEVCTL_PAYLOAD_* (Pali Rohár)
         - Set Max Payload Size to 512 bytes per Marvell spec (Pali Rohár)
         - Downgrade PIO Response Status messages to debug level (Marek Behún)
         - Preserve CRS SV (Config Request Retry Software Visibility) bit in
           emulated Root Control register (Pali Rohár)
         - Fix issue in configuring reference clock (Pali Rohár)
         - Don't clear status bits for masked interrupts (Pali Rohár)
         - Don't mask unused interrupts (Pali Rohár)
         - Avoid code repetition in advk_pcie_rd_conf() (Marek Behún)
         - Retry config accesses on CRS response (Pali Rohár)
         - Simplify emulated Root Capabilities initialization (Pali Rohár)
         - Fix several link training issues (Pali Rohár)
         - Fix link-up checking via LTSSM (Pali Rohár)
         - Fix reporting of Data Link Layer Link Active (Pali Rohár)
         - Fix emulation of W1C bits (Marek Behún)
         - Fix MSI domain .alloc() method to return zero on success (Marek
           Behún)
         - Read entire 16-bit MSI vector in MSI handler, not just low 8 bits
           (Marek Behún)
         - Clear Root Port I/O Space, Memory Space, and Bus Master Enable bits
           at startup; PCI core will set those as necessary (Pali Rohár)
         - When operating as a Root Port, set class code to "PCI Bridge"
           instead of the default "Mass Storage Controller" (Pali Rohár)
         - Add emulation for PCI_BRIDGE_CTL_BUS_RESET since aardvark doesn't
           implement this per spec (Pali Rohár)
         - Add emulation of option ROM BAR since aardvark doesn't implement
           this per spec (Pali Rohár)
      
        MediaTek MT7621 PCIe controller driver:
         - Add MediaTek MT7621 PCIe host controller driver and DT binding
           (Sergio Paracuellos)
      
        Qualcomm PCIe controller driver:
         - Add SC8180x compatible string (Bjorn Andersson)
         - Add endpoint controller driver and DT binding (Manivannan
           Sadhasivam)
         - Restructure to use of_device_get_match_data() (Prasad Malisetty)
         - Add SC7280-specific pcie_1_pipe_clk_src handling (Prasad Malisetty)
      
        Renesas R-Car PCIe controller driver:
         - Remove unnecessary includes (Geert Uytterhoeven)
      
        Rockchip DesignWare PCIe controller driver:
         - Add DT binding (Simon Xue)
      
        Socionext UniPhier Pro5 controller driver:
         - Serialize INTx masking/unmasking (Kunihiko Hayashi)
      
        Synopsys DesignWare PCIe controller driver:
         - Run dwc .host_init() method before registering MSI interrupt
           handler so we can deal with pending interrupts left by bootloader
           (Bjorn Andersson)
         - Clean up Kconfig dependencies (Andy Shevchenko)
         - Export symbols to allow more modular drivers (Luca Ceresoli)
      
        TI DRA7xx PCIe controller driver:
         - Allow host and endpoint drivers to be modules (Luca Ceresoli)
         - Enable external clock if present (Luca Ceresoli)
      
        TI J721E PCIe driver:
         - Disable PHY when probe fails after initializing it (Christophe
           JAILLET)
      
        MicroSemi Switchtec management driver:
         - Return error to application when command execution fails because an
           out-of-band reset has cleared the device BARs, Memory Space Enable,
           etc (Kelvin Cao)
         - Fix MRPC error status handling issue (Kelvin Cao)
         - Mask out other bits when reading of management VEP instance ID
           (Kelvin Cao)
         - Return EOPNOTSUPP instead of ENOTSUPP from sysfs show functions
           (Kelvin Cao)
         - Add check of event support (Logan Gunthorpe)
      
        Miscellaneous:
         - Remove unused pci_pool wrappers, which have been replaced by
           dma_pool (Cai Huoqing)
         - Use 'unsigned int' instead of bare 'unsigned' (Krzysztof
           Wilczyński)
         - Use kstrtobool() directly, sans strtobool() wrapper (Krzysztof
           Wilczyński)
         - Fix some sscanf(), sprintf() format mismatches (Krzysztof
           Wilczyński)
         - Update PCI subsystem information in MAINTAINERS (Krzysztof
           Wilczyński)
         - Correct some misspellings (Krzysztof Wilczyński)"
      
      * tag 'pci-v5.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (137 commits)
        PCI: Add ACS quirk for Pericom PI7C9X2G switches
        PCI: apple: Configure RID to SID mapper on device addition
        iommu/dart: Exclude MSI doorbell from PCIe device IOVA range
        PCI: apple: Implement MSI support
        PCI: apple: Add INTx and per-port interrupt support
        PCI: kirin: Allow removing the driver
        PCI: kirin: De-init the dwc driver
        PCI: kirin: Disable clkreq during poweroff sequence
        PCI: kirin: Move the power-off code to a common routine
        PCI: kirin: Add power_off support for Kirin 960 PHY
        PCI: kirin: Allow building it as a module
        PCI: kirin: Add MODULE_* macros
        PCI: kirin: Add Kirin 970 compatible
        PCI: kirin: Support PERST# GPIOs for HiKey970 external PEX 8606 bridge
        PCI: apple: Set up reference clocks when probing
        PCI: apple: Add initial hardware bring-up
        PCI: of: Allow matching of an interrupt-map local to a PCI device
        of/irq: Allow matching of an interrupt-map local to an interrupt controller
        irqdomain: Make of_phandle_args_to_fwspec() generally available
        PCI: Do not enable AtomicOps on VFs
        ...
      0c5c62dd
    • Linus Torvalds's avatar
      Merge branch 'akpm' (patches from Andrew) · 512b7931
      Linus Torvalds authored
      Merge misc updates from Andrew Morton:
       "257 patches.
      
        Subsystems affected by this patch series: scripts, ocfs2, vfs, and
        mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache,
        gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc,
        pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools,
        memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm,
        vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram,
        cleanups, kfence, and damon)"
      
      * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (257 commits)
        mm/damon: remove return value from before_terminate callback
        mm/damon: fix a few spelling mistakes in comments and a pr_debug message
        mm/damon: simplify stop mechanism
        Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions
        Docs/admin-guide/mm/damon/start: simplify the content
        Docs/admin-guide/mm/damon/start: fix a wrong link
        Docs/admin-guide/mm/damon/start: fix wrong example commands
        mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on
        mm/damon: remove unnecessary variable initialization
        Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM
        mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)
        selftests/damon: support watermarks
        mm/damon/dbgfs: support watermarks
        mm/damon/schemes: activate schemes based on a watermarks mechanism
        tools/selftests/damon: update for regions prioritization of schemes
        mm/damon/dbgfs: support prioritization weights
        mm/damon/vaddr,paddr: support pageout prioritization
        mm/damon/schemes: prioritize regions within the quotas
        mm/damon/selftests: support schemes quotas
        mm/damon/dbgfs: support quotas of schemes
        ...
      512b7931
    • Changbin Du's avatar
      mm/damon: remove return value from before_terminate callback · 658f9ae7
      Changbin Du authored
      Since the return value of 'before_terminate' callback is never used, we
      make it have no return value.
      
      Link: https://lkml.kernel.org/r/20211029005023.8895-1-changbin.du@gmail.comSigned-off-by: default avatarChangbin Du <changbin.du@gmail.com>
      Reviewed-by: default avatarSeongJae Park <sj@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      658f9ae7
    • Colin Ian King's avatar
    • Changbin Du's avatar
      mm/damon: simplify stop mechanism · 0f91d133
      Changbin Du authored
      A kernel thread can exit gracefully with kthread_stop().  So we don't
      need a new flag 'kdamond_stop'.  And to make sure the task struct is not
      freed when accessing it, get reference to it before termination.
      
      Link: https://lkml.kernel.org/r/20211027130517.4404-1-changbin.du@gmail.comSigned-off-by: default avatarChangbin Du <changbin.du@gmail.com>
      Reviewed-by: default avatarSeongJae Park <sj@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0f91d133
    • SeongJae Park's avatar
      Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions · 0d16cfd4
      SeongJae Park authored
      Some descriptions of page flags in 'pagemap.rst' are written in
      assumption of none-rst, which respects every new line, as below:
      
          7 - SLAB
             page is managed by the SLAB/SLOB/SLUB/SLQB kernel memory allocator
             When compound page is used, SLUB/SLQB will only set this flag on the head
      
      Because rst ignores the new line between the first sentence and second
      sentence, resulting html looks a little bit weird, as below.
      
          7 - SLAB
          page is managed by the SLAB/SLOB/SLUB/SLQB kernel memory allocator When
                                                                             ^
          compound page is used, SLUB/SLQB will only set this flag on the head
          page; SLOB will not flag it at all.
      
      This change makes it more natural and consistent with other parts in the
      rendered version.
      
      Link: https://lkml.kernel.org/r/20211022090311.3856-5-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Peter Xu <peterx@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0d16cfd4
    • SeongJae Park's avatar
      Docs/admin-guide/mm/damon/start: simplify the content · b1eee3c5
      SeongJae Park authored
      Information in 'TL; DR' section of 'Getting Started' is duplicated in
      other parts of the doc.  It is also asking readers to visit the access
      pattern visualizations gallery web site to show the results of example
      visualization commands, while the users of the commands can use terminal
      output.
      
      To make the doc simple, this removes the duplicated 'TL; DR' section and
      replaces the visualization example commands with versions using terminal
      outputs.
      
      Link: https://lkml.kernel.org/r/20211022090311.3856-4-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Peter Xu <peterx@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b1eee3c5
    • SeongJae Park's avatar
      Docs/admin-guide/mm/damon/start: fix a wrong link · 49ce7dee
      SeongJae Park authored
      The 'Getting Started' of DAMON is providing a link to DAMON's user
      interface document while saying about its user space tool's detailed
      usages.  This fixes the link.
      
      Link: https://lkml.kernel.org/r/20211022090311.3856-3-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Peter Xu <peterx@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      49ce7dee
    • SeongJae Park's avatar
      Docs/admin-guide/mm/damon/start: fix wrong example commands · 82e3fff5
      SeongJae Park authored
      Patch series "Fix trivial nits in Documentation/admin-guide/mm".
      
      This patchset fixes trivial nits in admin guide documents for DAMON and
      pagemap.
      
      This patch (of 4):
      
      Some of the example commands in DAMON getting started guide are
      outdated, missing sudo, or just wrong.  This fixes those.
      
      Link: https://lkml.kernel.org/r/20211022090311.3856-2-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Peter Xu <peterx@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      82e3fff5
    • Xin Hao's avatar
      mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on · b5ca3e83
      Xin Hao authored
      When the ctx->adaptive_targets list is empty, I did some test on
      monitor_on interface like this.
      
          # cat /sys/kernel/debug/damon/target_ids
          #
          # echo on > /sys/kernel/debug/damon/monitor_on
          # damon: kdamond (5390) starts
      
      Though the ctx->adaptive_targets list is empty, but the kthread_run
      still be called, and the kdamond.x thread still be created, this is
      meaningless.
      
      So there adds a judgment in 'dbgfs_monitor_on_write', if the
      ctx->adaptive_targets list is empty, return -EINVAL.
      
      Link: https://lkml.kernel.org/r/0a60a6e8ec9d71989e0848a4dc3311996ca3b5d4.1634720326.git.xhao@linux.alibaba.comSigned-off-by: default avatarXin Hao <xhao@linux.alibaba.com>
      Reviewed-by: default avatarSeongJae Park <sj@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b5ca3e83
    • Xin Hao's avatar
      mm/damon: remove unnecessary variable initialization · a460a360
      Xin Hao authored
      Patch series "mm/damon: Fix some small bugs", v4.
      
      This patch (of 2):
      
      In 'damon_va_apply_three_regions' there is no need to set variable 'i'
      to zero.
      
      Link: https://lkml.kernel.org/r/b7df8d3dad0943a37e01f60c441b1968b2b20354.1634720326.git.xhao@linux.alibaba.com
      Link: https://lkml.kernel.org/r/cover.1634720326.git.xhao@linux.alibaba.comSigned-off-by: default avatarXin Hao <xhao@linux.alibaba.com>
      Reviewed-by: default avatarSeongJae Park <sj@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a460a360
    • SeongJae Park's avatar
      Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM · bec976b6
      SeongJae Park authored
      This adds an admin-guide document for DAMON-based Reclamation.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-16-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bec976b6
    • SeongJae Park's avatar
      mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM) · 43b0536c
      SeongJae Park authored
      This implements a new kernel subsystem that finds cold memory regions
      using DAMON and reclaims those immediately.  It is intended to be used
      as proactive lightweigh reclamation logic for light memory pressure.
      For heavy memory pressure, it could be inactivated and fall back to the
      traditional page-scanning based reclamation.
      
      It's implemented on top of DAMON framework to use the DAMON-based
      Operation Schemes (DAMOS) feature.  It utilizes all the DAMOS features
      including speed limit, prioritization, and watermarks.
      
      It could be enabled and tuned in boot time via the kernel boot
      parameter, and in run time via its module parameters
      ('/sys/module/damon_reclaim/parameters/') interface.
      
      [yangyingliang@huawei.com: fix error return code in damon_reclaim_turn()]
        Link: https://lkml.kernel.org/r/20211025124500.2758060-1-yangyingliang@huawei.com
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-15-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      43b0536c
    • SeongJae Park's avatar
      selftests/damon: support watermarks · 1dc90ccd
      SeongJae Park authored
      This updates DAMON selftests for 'schemes' debugfs file to reflect the
      changes in the format.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-14-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1dc90ccd
    • SeongJae Park's avatar
      mm/damon/dbgfs: support watermarks · ae666a6d
      SeongJae Park authored
      This updates DAMON debugfs interface to support the watermarks based
      schemes activation.  For this, now 'schemes' file receives five more
      values.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-13-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ae666a6d
    • SeongJae Park's avatar
      mm/damon/schemes: activate schemes based on a watermarks mechanism · ee801b7d
      SeongJae Park authored
      DAMON-based operation schemes need to be manually turned on and off.  In
      some use cases, however, the condition for turning a scheme on and off
      would depend on the system's situation.  For example, schemes for
      proactive pages reclamation would need to be turned on when some memory
      pressure is detected, and turned off when the system has enough free
      memory.
      
      For easier control of schemes activation based on the system situation,
      this introduces a watermarks-based mechanism.  The client can describe
      the watermark metric (e.g., amount of free memory in the system),
      watermark check interval, and three watermarks, namely high, mid, and
      low.  If the scheme is deactivated, it only gets the metric and compare
      that to the three watermarks for every check interval.  If the metric is
      higher than the high watermark, the scheme is deactivated.  If the
      metric is between the mid watermark and the low watermark, the scheme is
      activated.  If the metric is lower than the low watermark, the scheme is
      deactivated again.  This is to allow users fall back to traditional
      page-granularity mechanisms.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-12-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ee801b7d
    • SeongJae Park's avatar
      tools/selftests/damon: update for regions prioritization of schemes · 5a0d6a08
      SeongJae Park authored
      This updates the DAMON selftests for 'schemes' debugfs file, as the file
      format is updated.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-11-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5a0d6a08
    • SeongJae Park's avatar
      mm/damon/dbgfs: support prioritization weights · f4a68b4a
      SeongJae Park authored
      This allows DAMON debugfs interface users set the prioritization weights
      by putting three more numbers to the 'schemes' file.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-10-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f4a68b4a
    • SeongJae Park's avatar
      mm/damon/vaddr,paddr: support pageout prioritization · 198f0f4c
      SeongJae Park authored
      This makes the default monitoring primitives for virtual address spaces
      and the physical address sapce to support memory regions prioritization
      for 'PAGEOUT' DAMOS action.  It calculates hotness of each region as
      weighted sum of 'nr_accesses' and 'age' of the region and get the
      priority score as reverse of the hotness, so that cold regions can be
      paged out first.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-9-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      198f0f4c
    • SeongJae Park's avatar
      mm/damon/schemes: prioritize regions within the quotas · 38683e00
      SeongJae Park authored
      This makes DAMON apply schemes to regions having higher priority first,
      if it cannot apply schemes to all regions due to the quotas.
      
      The prioritization function should be implemented in the monitoring
      primitives.  Those would commonly calculate the priority of the region
      using attributes of regions, namely 'size', 'nr_accesses', and 'age'.
      For example, some primitive would calculate the priority of each region
      using a weighted sum of 'nr_accesses' and 'age' of the region.
      
      The optimal weights would depend on give environments, so this makes
      those customizable.  Nevertheless, the score calculation functions are
      only encouraged to respect the weights, not mandated.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-8-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      38683e00
    • SeongJae Park's avatar
      mm/damon/selftests: support schemes quotas · a2cb4dd0
      SeongJae Park authored
      This updates DAMON selftests to support updated schemes debugfs file
      format for the quotas.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-7-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a2cb4dd0
    • SeongJae Park's avatar
      mm/damon/dbgfs: support quotas of schemes · d7d0ec85
      SeongJae Park authored
      This makes the debugfs interface of DAMON support the scheme quotas by
      chaning the format of the input for the schemes file.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-6-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d7d0ec85
    • SeongJae Park's avatar
      mm/damon/schemes: implement time quota · 1cd24303
      SeongJae Park authored
      The size quota feature of DAMOS is useful for IO resource-critical
      systems, but not so intuitive for CPU time-critical systems.  Systems
      using zram or zswap-like swap device would be examples.
      
      To provide another intuitive ways for such systems, this implements
      time-based quota for DAMON-based Operation Schemes.  If the quota is
      set, DAMOS tries to use only up to the user-defined quota of CPU time
      within a given time window.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-5-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1cd24303
    • SeongJae Park's avatar
      mm/damon/schemes: skip already charged targets and regions · 50585192
      SeongJae Park authored
      If DAMOS has stopped applying action in the middle of a group of memory
      regions due to its size quota, it starts the work again from the
      beginning of the address space in the next charge window.  If there is a
      huge memory region at the beginning of the address space and it fulfills
      the scheme's target data access pattern always, the action will applied
      to only the region.
      
      This mitigates the case by skipping memory regions that charged in
      current charge window at the beginning of next charge window.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-4-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      50585192
    • SeongJae Park's avatar
      mm/damon/schemes: implement size quota for schemes application speed control · 2b8a248d
      SeongJae Park authored
      There could be arbitrarily large memory regions fulfilling the target
      data access pattern of a DAMON-based operation scheme.  In the case,
      applying the action of the scheme could incur too high overhead.  To
      provide an intuitive way for avoiding it, this implements a feature
      called size quota.  If the quota is set, DAMON tries to apply the action
      only up to the given amount of memory regions within a given time
      window.
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-3-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2b8a248d
    • SeongJae Park's avatar
      mm/damon/paddr: support the pageout scheme · 57223ac2
      SeongJae Park authored
      Introduction
      ============
      
      This patchset 1) makes the engine for general data access
      pattern-oriented memory management (DAMOS) be more useful for production
      environments, and 2) implements a static kernel module for lightweight
      proactive reclamation using the engine.
      
      Proactive Reclamation
      ---------------------
      
      On general memory over-committed systems, proactively reclaiming cold
      pages helps saving memory and reducing latency spikes that incurred by
      the direct reclaim or the CPU consumption of kswapd, while incurring
      only minimal performance degradation[2].
      
      A Free Pages Reporting[8] based memory over-commit virtualization system
      would be one more specific use case.  In the system, the guest VMs
      reports their free memory to host, and the host reallocates the reported
      memory to other guests.  As a result, the system's memory utilization
      can be maximized.  However, the guests could be not so memory-frugal,
      because some kernel subsystems and user-space applications are designed
      to use as much memory as available.  Then, guests would report only
      small amount of free memory to host, results in poor memory utilization.
      Running the proactive reclamation in such guests could help mitigating
      this problem.
      
      Google has also implemented this idea and using it in their data center.
      They further proposed upstreaming it in LSFMM'19, and "the general
      consensus was that, while this sort of proactive reclaim would be useful
      for a number of users, the cost of this particular solution was too high
      to consider merging it upstream"[3].  The cost mainly comes from the
      coldness tracking.  Roughly speaking, the implementation periodically
      scans the 'Accessed' bit of each page.  For the reason, the overhead
      linearly increases as the size of the memory and the scanning frequency
      grows.  As a result, Google is known to dedicating one CPU for the work.
      That's a reasonable option to someone like Google, but it wouldn't be so
      to some others.
      
      DAMON and DAMOS: An engine for data access pattern-oriented memory management
      -----------------------------------------------------------------------------
      
      DAMON[4] is a framework for general data access monitoring.  Its
      adaptive monitoring overhead control feature minimizes its monitoring
      overhead.  It also let the upper-bound of the overhead be configurable
      by clients, regardless of the size of the monitoring target memory.
      While monitoring 70 GiB memory of a production system every 5
      milliseconds, it consumes less than 1% single CPU time.  For this, it
      could sacrify some of the quality of the monitoring results.
      Nevertheless, the lower-bound of the quality is configurable, and it
      uses a best-effort algorithm for better quality.  Our test results[5]
      show the quality is practical enough.  From the production system
      monitoring, we were able to find a 4 KiB region in the 70 GiB memory
      that shows highest access frequency.
      
      We normally don't monitor the data access pattern just for fun but to
      improve something like memory management.  Proactive reclamation is one
      such usage.  For such general cases, DAMON provides a feature called
      DAMon-based Operation Schemes (DAMOS)[6].  It makes DAMON an engine for
      general data access pattern oriented memory management.  Using this,
      clients can ask DAMON to find memory regions of specific data access
      pattern and apply some memory management action (e.g., page out, move to
      head of the LRU list, use huge page, ...).  We call the request
      'scheme'.
      
      Proactive Reclamation on top of DAMON/DAMOS
      -------------------------------------------
      
      Therefore, by using DAMON for the cold pages detection, the proactive
      reclamation's monitoring overhead issue can be solved.  Actually, we
      previously implemented a version of proactive reclamation using DAMOS
      and achieved noticeable improvements with our evaluation setup[5].
      Nevertheless, it more for a proof-of-concept, rather than production
      uses.  It supports only virtual address spaces of processes, and require
      additional tuning efforts for given workloads and the hardware.  For the
      tuning, we introduced a simple auto-tuning user space tool[8].  Google
      is also known to using a ML-based similar approach for their fleets[2].
      But, making it just works with intuitive knobs in the kernel would be
      helpful for general users.
      
      To this end, this patchset improves DAMOS to be ready for such
      production usages, and implements another version of the proactive
      reclamation, namely DAMON_RECLAIM, on top of it.
      
      DAMOS Improvements: Aggressiveness Control, Prioritization, and Watermarks
      --------------------------------------------------------------------------
      
      First of all, the current version of DAMOS supports only virtual address
      spaces.  This patchset makes it supports the physical address space for
      the page out action.
      
      Next major problem of the current version of DAMOS is the lack of the
      aggressiveness control, which can results in arbitrary overhead.  For
      example, if huge memory regions having the data access pattern of
      interest are found, applying the requested action to all of the regions
      could incur significant overhead.  It can be controlled by tuning the
      target data access pattern with manual or automated approaches[2,7].
      But, some people would prefer the kernel to just work with only
      intuitive tuning or default values.
      
      For such cases, this patchset implements a safeguard, namely time/size
      quota.  Using this, the clients can specify up to how much time can be
      used for applying the action, and/or up to how much memory regions the
      action can be applied within a user-specified time duration.  A followup
      question is, to which memory regions should the action applied within
      the limits? We implement a simple regions prioritization mechanism for
      each action and make DAMOS to apply the action to high priority regions
      first.  It also allows clients tune the prioritization mechanism to use
      different weights for size, access frequency, and age of memory regions.
      This means we could use not only LRU but also LFU or some fancy
      algorithms like CAR[9] with lightweight overhead.
      
      Though DAMON is lightweight, someone would want to remove even the cold
      pages monitoring overhead when it is unnecessary.  Currently, it should
      manually turned on and off by clients, but some clients would simply
      want to turn it on and off based on some metrics like free memory ratio
      or memory fragmentation.  For such cases, this patchset implements a
      watermarks-based automatic activation feature.  It allows the clients
      configure the metric of their interest, and three watermarks of the
      metric.  If the metric is higher than the high watermark or lower than
      the low watermark, the scheme is deactivated.  If the metric is lower
      than the mid watermark but higher than the low watermark, the scheme is
      activated.
      
      DAMON-based Reclaim
      -------------------
      
      Using the improved version of DAMOS, this patchset implements a static
      kernel module called 'damon_reclaim'.  It finds memory regions that
      didn't accessed for specific time duration and page out.  Consuming too
      much CPU for the paging out operations, or doing pageout too frequently
      can be critical for systems configuring their swap devices with
      software-defined in-memory block devices like zram/zswap or total number
      of writes limited devices like SSDs, respectively.  To avoid the
      problems, the time/size quotas can be configured.  Under the quotas, it
      pages out memory regions that didn't accessed longer first.  Also, to
      remove the monitoring overhead under peaceful situation, and to fall
      back to the LRU-list based page granularity reclamation when it doesn't
      make progress, the three watermarks based activation mechanism is used,
      with the free memory ratio as the watermark metric.
      
      For convenient configurations, it provides several module parameters.
      Using these, sysadmins can enable/disable it, and tune its parameters
      including the coldness identification time threshold, the time/size
      quotas and the three watermarks.
      
      Evaluation
      ==========
      
      In short, DAMON_RECLAIM with 50ms/s time quota and regions
      prioritization on v5.15-rc5 Linux kernel with ZRAM swap device achieves
      38.58% memory saving with only 1.94% runtime overhead.  For this,
      DAMON_RECLAIM consumes only 4.97% of single CPU time.
      
      Setup
      -----
      
      We evaluate DAMON_RECLAIM to show how each of the DAMOS improvements
      make effect.  For this, we measure DAMON_RECLAIM's CPU consumption,
      entire system memory footprint, total number of major page faults, and
      runtime of 24 realistic workloads in PARSEC3 and SPLASH-2X benchmark
      suites on my QEMU/KVM based virtual machine.  The virtual machine runs
      on an i3.metal AWS instance, has 130GiB memory, and runs a linux kernel
      built on latest -mm tree[1] plus this patchset.  It also utilizes a 4
      GiB ZRAM swap device.  We repeats the measurement 5 times and use
      averages.
      
      [1] https://github.com/hnaz/linux-mm/tree/v5.15-rc5-mmots-2021-10-13-19-55
      
      Detailed Results
      ----------------
      
      The results are summarized in the below table.
      
      With coldness identification threshold of 5 seconds, DAMON_RECLAIM
      without the time quota-based speed limit achieves 47.21% memory saving,
      but incur 4.59% runtime slowdown to the workloads on average.  For this,
      DAMON_RECLAIM consumes about 11.28% single CPU time.
      
      Applying time quotas of 200ms/s, 50ms/s, and 10ms/s without the regions
      prioritization reduces the slowdown to 4.89%, 2.65%, and 1.5%,
      respectively.  Time quota of 200ms/s (20%) makes no real change compared
      to the quota unapplied version, because the quota unapplied version
      consumes only 11.28% CPU time.  DAMON_RECLAIM's CPU utilization also
      similarly reduced: 11.24%, 5.51%, and 2.01% of single CPU time.  That
      is, the overhead is proportional to the speed limit.  Nevertheless, it
      also reduces the memory saving because it becomes less aggressive.  In
      detail, the three variants show 48.76%, 37.83%, and 7.85% memory saving,
      respectively.
      
      Applying the regions prioritization (page out regions that not accessed
      longer first within the time quota) further reduces the performance
      degradation.  Runtime slowdowns and total number of major page faults
      increase has been 4.89%/218,690% -> 4.39%/166,136% (200ms/s),
      2.65%/111,886% -> 1.94%/59,053% (50ms/s), and 1.5%/34,973.40% ->
      2.08%/8,781.75% (10ms/s).  The runtime under 10ms/s time quota has
      increased with prioritization, but apparently that's under the margin of
      error.
      
          time quota   prioritization  memory_saving  cpu_util  slowdown  pgmajfaults overhead
          N            N               47.21%         11.28%    4.59%     194,802%
          200ms/s      N               48.76%         11.24%    4.89%     218,690%
          50ms/s       N               37.83%         5.51%     2.65%     111,886%
          10ms/s       N               7.85%          2.01%     1.5%      34,793.40%
          200ms/s      Y               50.08%         10.38%    4.39%     166,136%
          50ms/s       Y               38.58%         4.97%     1.94%     59,053%
          10ms/s       Y               3.63%          1.73%     2.08%     8,781.75%
      
      Baseline and Complete Git Trees
      ===============================
      
      The patches are based on the latest -mm tree
      (v5.15-rc5-mmots-2021-10-13-19-55).  You can also clone the complete git tree
      from:
      
          $ git clone git://github.com/sjp38/linux -b damon_reclaim/patches/v1
      
      The web is also available:
      https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git/tag/?h=damon_reclaim/patches/v1
      
      Sequence Of Patches
      ===================
      
      The first patch makes DAMOS support the physical address space for the
      page out action.  Following five patches (patches 2-6) implement the
      time/size quotas.  Next four patches (patches 7-10) implement the memory
      regions prioritization within the limit.  Then, three following patches
      (patches 11-13) implement the watermarks-based schemes activation.
      
      Finally, the last two patches (patches 14-15) implement and document the
      DAMON-based reclamation using the advanced DAMOS.
      
      [1] https://www.kernel.org/doc/html/v5.15-rc1/vm/damon/index.html
      [2] https://research.google/pubs/pub48551/
      [3] https://lwn.net/Articles/787611/
      [4] https://damonitor.github.io
      [5] https://damonitor.github.io/doc/html/latest/vm/damon/eval.html
      [6] https://lore.kernel.org/linux-mm/20211001125604.29660-1-sj@kernel.org/
      [7] https://github.com/awslabs/damoos
      [8] https://www.kernel.org/doc/html/latest/vm/free_page_reporting.html
      [9] https://www.usenix.org/conference/fast-04/car-clock-adaptive-replacement
      
      This patch (of 15):
      
      This makes the DAMON primitives for physical address space support the
      pageout action for DAMON-based Operation Schemes.  With this commit,
      hence, users can easily implement system-level data access-aware
      reclamations using DAMOS.
      
      [sj@kernel.org: fix missing-prototype build warning]
        Link: https://lkml.kernel.org/r/20211025064220.13904-1-sj@kernel.org
      
      Link: https://lkml.kernel.org/r/20211019150731.16699-1-sj@kernel.org
      Link: https://lkml.kernel.org/r/20211019150731.16699-2-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Marco Elver <elver@google.com>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      57223ac2
    • Rongwei Wang's avatar
      mm/damon/dbgfs: remove unnecessary variables · 9210622a
      Rongwei Wang authored
      In some functions, it's unnecessary to declare 'err' and 'ret' variables
      at the same time.  This patch mainly to simplify the issue of such
      declarations by reusing one variable.
      
      Link: https://lkml.kernel.org/r/20211014073014.35754-1-sj@kernel.orgSigned-off-by: default avatarRongwei Wang <rongwei.wang@linux.alibaba.com>
      Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9210622a
    • Rikard Falkeborn's avatar
      mm/damon/vaddr: constify static mm_walk_ops · 199b50f4
      Rikard Falkeborn authored
      The only usage of these structs is to pass their addresses to
      walk_page_range(), which takes a pointer to const mm_walk_ops as
      argument.  Make them const to allow the compiler to put them in
      read-only memory.
      
      Link: https://lkml.kernel.org/r/20211014075042.17174-2-rikard.falkeborn@gmail.comSigned-off-by: default avatarRikard Falkeborn <rikard.falkeborn@gmail.com>
      Reviewed-by: default avatarSeongJae Park <sj@kernel.org>
      Reviewed-by: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      199b50f4
    • SeongJae Park's avatar
      Docs/DAMON: document physical memory monitoring support · c6380721
      SeongJae Park authored
      This updates the DAMON documents for the physical memory address space
      monitoring support.
      
      Link: https://lkml.kernel.org/r/20211012205711.29216-8-sj@kernel.orgSigned-off-by: default avatarSeongJae Park <sj@kernel.org>
      Cc: Amit Shah <amit@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Brendan Higgins <brendanhiggins@google.com>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: David Rienjes <rientjes@google.com>
      Cc: David Woodhouse <dwmw@amazon.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Leonard Foerster <foersleo@amazon.de>
      Cc: Marco Elver <elver@google.com>
      Cc: Markus Boehme <markubo@amazon.de>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c6380721