linux-stable.git/tools/perf/arch, branch v6.1.78

perf tool x86: Fix perf_env memory leak

2023-07-19T14:21:38+00:00

[ Upstream commit 99d4850062a84564f36923764bb93935ef2ed108 ]

Found by leak sanitizer:
```
==1632594==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 21 byte(s) in 1 object(s) allocated from:
    #0 0x7f2953a7077b in __interceptor_strdup ../../../../src/libsanitizer/asan/asan_interceptors.cpp:439
    #1 0x556701d6fbbf in perf_env__read_cpuid util/env.c:369
    #2 0x556701d70589 in perf_env__cpuid util/env.c:465
    #3 0x55670204bba2 in x86__is_amd_cpu arch/x86/util/env.c:14
    #4 0x5567020487a2 in arch__post_evsel_config arch/x86/util/evsel.c:83
    #5 0x556701d8f78b in evsel__config util/evsel.c:1366
    #6 0x556701ef5872 in evlist__config util/record.c:108
    #7 0x556701cd6bcd in test__PERF_RECORD tests/perf-record.c:112
    #8 0x556701cacd07 in run_test tests/builtin-test.c:236
    #9 0x556701cacfac in test_and_print tests/builtin-test.c:265
    #10 0x556701cadddb in __cmd_test tests/builtin-test.c:402
    #11 0x556701caf2aa in cmd_test tests/builtin-test.c:559
    #12 0x556701d3b557 in run_builtin tools/perf/perf.c:323
    #13 0x556701d3bac8 in handle_internal_command tools/perf/perf.c:377
    #14 0x556701d3be90 in run_argv tools/perf/perf.c:421
    #15 0x556701d3c3f8 in main tools/perf/perf.c:537
    #16 0x7f2952a46189 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58

SUMMARY: AddressSanitizer: 21 byte(s) leaked in 1 allocation(s).
```

Fixes: f7b58cbdb3ff36eb ("perf mem/c2c: Add load store event mappings for AMD")
Signed-off-by: Ian Rogers 
Acked-by: Ravi Bangoria 
Tested-by: Arnaldo Carvalho de Melo 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Link: https://lore.kernel.org/r/20230613235416.1650755-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

perf tool x86: Consolidate is_amd check into single function

2023-07-19T14:21:38+00:00

[ Upstream commit 0cd1ca4650c9cf5f318110f67d39cbebae3693b3 ]

There are multiple places where x86 specific code determines AMD vs
Intel arch and acts based on that. Consolidate those checks into a
single function.

Signed-off-by: Ravi Bangoria 
Acked-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Ali Saidi 
Cc: Ananth Narayan 
Cc: James Clark 
Cc: Jiri Olsa 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Madhavan Srinivasan 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Sandipan Das 
Cc: Santosh Shukla 
Link: https://lore.kernel.org/r/20230613095506.547-3-ravi.bangoria@amd.com
Signed-off-by: Arnaldo Carvalho de Melo 
Stable-dep-of: 99d4850062a8 ("perf tool x86: Fix perf_env memory leak")
Signed-off-by: Sasha Levin

tools headers UAPI: Sync powerpc syscall tables with the kernel sources

2022-10-25T20:40:48+00:00

To pick the changes in these csets:

  e237506238352f3b ("powerpc/32: fix syscall wrappers with 64-bit arguments of unaligned register-pairs")

That doesn't cause any changes in the perf tools.

As a reminder, this table is used in tools perf to allow features such as:

  [root@five ~]# perf trace -e set_mempolicy_home_node
  ^C[root@five ~]#
  [root@five ~]# perf trace -v -e set_mempolicy_home_node
  Using CPUID AuthenticAMD-25-21-0
  event qualifier tracepoint filter: (common_pid != 253729 && common_pid != 3585) && (id == 450)
  mmap size 528384B
  ^C[root@five ~]
  [root@five ~]# perf trace -v -e set*  --max-events 5
  Using CPUID AuthenticAMD-25-21-0
  event qualifier tracepoint filter: (common_pid != 253734 && common_pid != 3585) && (id == 38 || id == 54 || id == 105 || id == 106 || id == 109 || id == 112 || id == 113 || id == 114 || id == 116 || id == 117 || id == 119 || id == 122 || id == 123 || id == 141 || id == 160 || id == 164 || id == 170 || id == 171 || id == 188 || id == 205 || id == 218 || id == 238 || id == 273 || id == 308 || id == 450)
  mmap size 528384B
       0.000 ( 0.008 ms): bash/253735 setpgid(pid: 253735 (bash), pgid: 253735 (bash))      = 0
    6849.011 ( 0.008 ms): bash/16046 setpgid(pid: 253736 (bash), pgid: 253736 (bash))       = 0
    6849.080 ( 0.005 ms): bash/253736 setpgid(pid: 253736 (bash), pgid: 253736 (bash))      = 0
    7437.718 ( 0.009 ms): gnome-shell/253737 set_robust_list(head: 0x7f34b527e920, len: 24) = 0
   13445.986 ( 0.010 ms): bash/16046 setpgid(pid: 253738 (bash), pgid: 253738 (bash))       = 0
  [root@five ~]#

That is the filter expression attached to the raw_syscalls:sys_{enter,exit}
tracepoints.

  $ find tools/perf/arch/ -name "syscall*tbl" | xargs grep -w set_mempolicy_home_node
  tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl:450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
  tools/perf/arch/powerpc/entry/syscalls/syscall.tbl:450 	nospu	set_mempolicy_home_node		sys_set_mempolicy_home_node
  tools/perf/arch/s390/entry/syscalls/syscall.tbl:450  common	set_mempolicy_home_node	sys_set_mempolicy_home_node	sys_set_mempolicy_home_node
  tools/perf/arch/x86/entry/syscalls/syscall_64.tbl:450	common	set_mempolicy_home_node	sys_set_mempolicy_home_node
  $

  $ grep -w set_mempolicy_home_node /tmp/build/perf/arch/x86/include/generated/asm/syscalls_64.c
	[450] = "set_mempolicy_home_node",
  $

This addresses these perf build warnings:

  Warning: Kernel ABI header at 'tools/include/uapi/asm-generic/unistd.h' differs from latest version at 'include/uapi/asm-generic/unistd.h'
  diff -u tools/include/uapi/asm-generic/unistd.h include/uapi/asm-generic/unistd.h
  Warning: Kernel ABI header at 'tools/perf/arch/x86/entry/syscalls/syscall_64.tbl' differs from latest version at 'arch/x86/entry/syscalls/syscall_64.tbl'
  diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
  Warning: Kernel ABI header at 'tools/perf/arch/powerpc/entry/syscalls/syscall.tbl' differs from latest version at 'arch/powerpc/kernel/syscalls/syscall.tbl'
  diff -u tools/perf/arch/powerpc/entry/syscalls/syscall.tbl arch/powerpc/kernel/syscalls/syscall.tbl
  Warning: Kernel ABI header at 'tools/perf/arch/s390/entry/syscalls/syscall.tbl' differs from latest version at 'arch/s390/kernel/syscalls/syscall.tbl'
  diff -u tools/perf/arch/s390/entry/syscalls/syscall.tbl arch/s390/kernel/syscalls/syscall.tbl
  Warning: Kernel ABI header at 'tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl' differs from latest version at 'arch/mips/kernel/syscalls/syscall_n64.tbl'
  diff -u tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl arch/mips/kernel/syscalls/syscall_n64.tbl

Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Link: https://lore.kernel.org/lkml/Y01HN2DGkWz8tC%2FJ@kernel.org/
Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace arm64: Add support for HiSilicon PCIe Tune and Trace device driver

2022-10-15T13:13:16+00:00

HiSilicon PCIe tune and trace device (PTT) could dynamically tune the
PCIe link's events, and trace the TLP headers).

This patch add support for PTT device in perf tool, so users could use
'perf record' to get TLP headers trace data.

Reviewed-by: Leo Yan 
Signed-off-by: Qi Liu 
Signed-off-by: Yicong Yang 
Acked-by: John Garry 
Cc: Alexander Shishkin 
Cc: Bjorn Helgaas 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jonathan Cameron 
Cc: Lorenzo Pieralisi 
Cc: Mark Rutland 
Cc: Mathieu Poirier 
Cc: Mike Leach 
Cc: Peter Zijlstra 
Cc: Qi Liu 
Cc: Shameerali Kolothum Thodi 
Cc: Shaokun Zhang 
Cc: Suzuki Poulouse 
Cc: Will Deacon 
Cc: Zeng Prime 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-pci@vger.kernel.org
Cc: linuxarm@huawei.com
Link: https://lore.kernel.org/r/20220927081400.14364-3-yangyicong@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace arm: Refactor event list iteration in auxtrace_record__init()

2022-10-15T13:13:16+00:00

Add find_pmu_for_event() and use to simplify logic in
auxtrace_record_init(). find_pmu_for_event() will be reused in
subsequent patches.

Reviewed-by: John Garry 
Reviewed-by: Jonathan Cameron 
Reviewed-by: Leo Yan 
Signed-off-by: Qi Liu 
Signed-off-by: Yicong Yang 
Cc: Alexander Shishkin 
Cc: Bjorn Helgaas 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Lorenzo Pieralisi 
Cc: Mark Rutland 
Cc: Mathieu Poirier 
Cc: Mike Leach 
Cc: Peter Zijlstra 
Cc: Qi Liu 
Cc: Shameerali Kolothum Thodi 
Cc: Shaokun Zhang 
Cc: Suzuki Poulouse 
Cc: Will Deacon 
Cc: Zeng Prime 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-pci@vger.kernel.org
Cc: linuxarm@huawei.com
Link: https://lore.kernel.org/r/20220927081400.14364-2-yangyicong@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix system_wide dummy event for hybrid

2022-10-15T13:13:16+00:00

User space tasks can migrate between CPUs, so when tracing selected CPUs,
system-wide sideband is still needed, however evlist->core.has_user_cpus
is not set in the hybrid case, so check the target cpu_list instead.

Fixes: 7d189cadbeebc778 ("perf intel-pt: Track sideband system-wide when needed")
Signed-off-by: Adrian Hunter 
Acked-by: Namhyung Kim 
Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20221012082259.22394-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Add missing condition flags for arm64

2022-10-14T13:47:35+00:00

According to the document [1], it can also have 'hs', 'lo', 'vc', 'vs' as a
condition code.  Let's add them too.

[1] https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/condition-codes-1-condition-flags-and-codes

Reported-by: Kevin Nomura 
Signed-off-by: Namhyung Kim 
Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jiri Olsa 
Cc: John Garry 
Cc: Leo Yan 
Cc: Mike Leach 
Cc: Peter Zijlstra 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20221006222232.266416-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

Merge tag 'perf-tools-for-v6.1-1-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux

2022-10-11T22:02:25+00:00

Pull perf tools updates from Arnaldo Carvalho de Melo:

 - Add support for AMD on 'perf mem' and 'perf c2c', the kernel
   enablement patches went via tip.

   Example:

      $ sudo perf mem record -- -c 10000
      ^C[ perf record: Woken up 227 times to write data ]
      [ perf record: Captured and wrote 58.760 MB perf.data (836978 samples) ]

      $ sudo perf mem report -F mem,sample,snoop
      Samples: 836K of event 'ibs_op//', Event count (approx.): 8418762
      Memory access                  Samples  Snoop
      N/A                             700620  N/A
      L1 hit                          126675  N/A
      L2 hit                             424  N/A
      L3 hit                             664  HitM
      L3 hit                              10  N/A
      Local RAM hit                        2  N/A
      Remote RAM (1 hop) hit            8558  N/A
      Remote Cache (1 hop) hit             3  N/A
      Remote Cache (1 hop) hit             2  HitM
      Remote Cache (2 hops) hit           10  HitM
      Remote Cache (2 hops) hit            6  N/A
      Uncached hit                         4  N/A
      $

 - "perf lock" improvements:

     - Add -E/--entries option to limit the number of entries to
       display, say to ask for just the top 5 contended locks.

     - Add -q/--quiet option to suppress header and debug messages.

     - Add a 'perf test' kernel lock contention entry to test 'perf
       lock'.

 - "perf lock contention" improvements:

     - Ask BPF's bpf_get_stackid() to skip some callchain entries.

       The ones closer to the tooling are bpf related and not that
       interesting, the ones calling the locking function are the ones
       we're interested in, example of a full, unskipped callstack:

     - Allow changing the callstack depth and number of entries to skip.

           1     10.74 us     10.74 us     10.74 us     spinlock   __bpf_trace_contention_begin+0xb
                          0xffffffffc03b5c47  bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117
                          0xffffffffc03b5c47  bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117
                          0xffffffffbb8b8e75  bpf_trace_run2+0x35
                          0xffffffffbb7eab9b  __bpf_trace_contention_begin+0xb
                          0xffffffffbb7ebe75  queued_spin_lock_slowpath+0x1f5
                          0xffffffffbc1c26ff  _raw_spin_lock+0x1f
                          0xffffffffbb841015  tick_do_update_jiffies64+0x25
                          0xffffffffbb8409ee  tick_irq_enter+0x9e

     - Show full callstack in verbose mode (-v option), sometimes this
       is desirable instead of showing just one callstack entry.

 - Allow multiple time ranges in 'perf record --delay' to help in
   reducing the amount of data collected from hardware tracing (Intel
   PT, etc) when there is a rough idea of periods of time where events
   of interest take time.

 - Add Intel PT to record only decoder debug messages when error
   happens.

 - Improve layout of Intel PT man page.

 - Add new branch types: alignment, data and inst faults and arch
   specific ones, such as fiq, debug_halt, debug_exit, debug_inst and
   debug_data on arm64.

   Kernel enablement went thru the tip tree.

 - Fix 'perf probe' error log check in 'perf test' when no debuginfo is
   available.

 - Fix 'perf stat' aggregation mode logic, it should be looking at the
   CPU not at the core number.

 - Fix flags parsing in 'perf trace' filters.

 - Introduce compact encoding of CPU range encoding on perf.data, to
   avoid having a bitmap with all the CPUs.

 - Improvements to the 'perf stat' metrics, including adding
   "core_wide", and computing "smt" from the CPU topology.

 - Add support to the new PERF_FORMAT_LOST perf_event_attr.read_format,
   that allows tooling to ask for the precise number of lost samples for
   a given event.

 - Add 'addr' sort key to see just the address of sampled instructions:

      $ perf record -o- true | perf report -i- -s addr
      [ perf record: Woken up 1 times to write data ]
      [ perf record: Captured and wrote 0.000 MB - ]
      # Samples: 12  of event 'cycles:u'
      # Event count (approx.): 252512
      #
      # Overhead  Address
      # ........  ..................
          42.96%  0x7f96f08443d7
          29.55%  0x7f96f0859b50
          14.76%  0x7f96f0852e02
           8.30%  0x7f96f0855028
           4.43%  0xffffffff8de01087

      perf annotate: Toggle full address <-> offset display

 - Add 'f' hotkey to the 'perf annotate' TUI interface when in
   'disassembler output' mode ('o' hotkey) to toggle showing full
   virtual address or just the offset.

 - Cache DSO build-ids when synthesizing PERF_RECORD_MMAP records for
   pre-existing threads, at the start of a 'perf record' session,
   speeding up that record startup phase.

 - Add a command line option to specify build ids in 'perf inject'.

 - Update JSON event files for the Intel alderlake, broadwell,
   broadwellde, broadwellx, cascadelakex, haswell, haswellx, icelake,
   icelakex, ivybridge, ivytown, jaketown, sandybridge, sapphirerapids,
   skylake, skylakex, and tigerlake processors.

 - Update vendor JSON event files for the ARM Neoverse V1 and E1
   platforms.

 - Add a 'perf test' entry for 'perf mem' where a struct has false
   sharing and this gets detected in the 'perf mem' output, tested with
   Intel, AMD and ARM64 systems.

 - Add a 'perf test' entry to test the resolution of java symbols, where
   an output like this is expected:

       8.18%  jshell    jitted-50116-29.so    [.] Interpreter
       0.75%  Thread-1  jitted-83602-1670.so  [.] jdk.internal.jimage.BasicImageReader.getString(int)

 - Add tests for the ARM64 CoreSight hardware tracing feature, with
   specially crafted pureloop, memcpy, thread loop and unroll tread that
   then gets traced and the output compared with expected output.

   Documentation explaining it is also included.

 - Add per thread Intel PT 'perf test' entry to check that
   PERF_RECORD_TEXT_POKE events are recorded per CPU, resulting in a
   mixture of per thread and per CPU events and mmaps, verify that this
   gets all recorded correctly.

 - Introduce pthread mutex wrappers to allow for building with clang's
   -Wthread-safety, i.e. using the "guarded_by" "pt_guarded_by"
   "lockable", "exclusive_lock_function", "exclusive_trylock_function",
   "exclusive_locks_required", and "no_thread_safety_analysis" compiler
   function attributes.

 - Fix empty version number when building outside of a git repo.

 - Improve feature detection display when multiple versions of a feature
   are present, such as for binutils libbfd, that has a mix of possible
   ways to detect according to the Linux distribution.

   Previously in some cases we had:

      Auto-detecting system features
      
      ...                                  libbfd: [ on  ]
      ...                          libbfd-liberty: [ on  ]
      ...                        libbfd-liberty-z: [ on  ]
      

   Now for this case we show just the main feature:

      Auto-detecting system features
      
      ...                                  libbfd: [ on  ]
      

 - Remove some unused structs, variables, macros, function prototypes
   and includes from various places.

* tag 'perf-tools-for-v6.1-1-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (169 commits)
  perf script: Add missing fields in usage hint
  perf mem: Print "LFB/MAB" for PERF_MEM_LVLNUM_LFB
  perf mem/c2c: Avoid printing empty lines for unsupported events
  perf mem/c2c: Add load store event mappings for AMD
  perf mem/c2c: Set PERF_SAMPLE_WEIGHT for LOAD_STORE events
  perf mem: Add support for printing PERF_MEM_LVLNUM_{CXL|IO}
  perf amd ibs: Sync arch/x86/include/asm/amd-ibs.h header with the kernel
  tools headers UAPI: Sync include/uapi/linux/perf_event.h header with the kernel
  perf stat: Fix cpu check to use id.cpu.cpu in aggr_printout()
  perf test coresight: Add relevant documentation about ARM64 CoreSight testing
  perf test: Add git ignore for tmp and output files of ARM CoreSight tests
  perf test coresight: Add unroll thread test shell script
  perf test coresight: Add unroll thread test tool
  perf test coresight: Add thread loop test shell scripts
  perf test coresight: Add thread loop test tool
  perf test coresight: Add memcpy thread test shell script
  perf test coresight: Add memcpy thread test tool
  perf test: Add git ignore for perf data generated by the ARM CoreSight tests
  perf test: Add arm64 asm pureloop test shell script
  perf test: Add asm pureloop test tool
  ...

perf mem/c2c: Add load store event mappings for AMD

2022-10-06T19:30:06+00:00

The 'perf mem' and 'perf c2c' tools are wrappers around 'perf record'
with mem load/ store events. IBS tagged load/store sample provides most
of the information needed for these tools. Wire in the "ibs_op//" event
as mem-ldst event for AMD.

There are some limitations though: Only load/store micro-ops provide
mem/c2c information. Whereas, IBS does not have a way to choose a
particular type of micro-op to tag. This results in many non-LS
micro-ops being tagged which appear as N/A in the perf report. IBS,
being an uncore pmu from kernel point of view[1], does not support per
process monitoring. Thus, perf mem/c2c on AMD are currently supported in
per-cpu mode only.

Example:

  $ sudo perf mem record -- -c 10000
  ^C[ perf record: Woken up 227 times to write data ]
  [ perf record: Captured and wrote 58.760 MB perf.data (836978 samples) ]

  $ sudo perf mem report -F mem,sample,snoop
  Samples: 836K of event 'ibs_op//', Event count (approx.): 8418762
  Memory access                  Samples  Snoop
  N/A                             700620  N/A
  L1 hit                          126675  N/A
  L2 hit                             424  N/A
  L3 hit                             664  HitM
  L3 hit                              10  N/A
  Local RAM hit                        2  N/A
  Remote RAM (1 hop) hit            8558  N/A
  Remote Cache (1 hop) hit             3  N/A
  Remote Cache (1 hop) hit             2  HitM
  Remote Cache (2 hops) hit           10  HitM
  Remote Cache (2 hops) hit            6  N/A
  Uncached hit                         4  N/A
  $

[1]: https://lore.kernel.org/lkml/20220829113347.295-1-ravi.bangoria@amd.com

Signed-off-by: Ravi Bangoria 
Acked-by: Jiri Olsa 
Cc: Alexander Shishkin 
Cc: Ali Saidi 
Cc: Ananth Narayan 
Cc: Andi Kleen 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Ian Rogers 
Cc: Ingo Molnar 
Cc: Joe Mario 
Cc: Kan Liang 
Cc: Kim Phillips 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Sandipan Das 
Cc: Santosh Shukla 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: x86@kernel.org
Link: https://lore.kernel.org/r/20221006153946.7816-6-ravi.bangoria@amd.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add evlist__add_sched_switch()

2022-10-06T11:03:53+00:00

Add a help to create a system-wide sched_switch event.  One merit is
that it sets the system-wide bit before adding it to evlist so that
the libperf can handle the cpu and thread maps correctly.

Reviewed-by: Adrian Hunter 
Signed-off-by: Namhyung Kim 
Cc: Ian Rogers 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Peter Zijlstra 
Link: https://lore.kernel.org/r/20221003204647.1481128-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo