Merge tag 'perf-core-for-mingo-20160511' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

User visible changes:

- Fix symbol insertion and callchain behavior in db-export (Chris Phlipot)

Infrastructure changes:

- Add libunwind build test (feature query), working towards supporting
  cross-platform DWARF callchains, starting with arm/arm64 (He Kuang)

- Use lsdir() more extensively (Masami Hiramatsu)

- Use SBUILD_ID_SIZE in places where the equivalent expression was
  being used (Masami Hiramatsu)

- Split some more 'perf trace' syscall arg beautifiers (Arnaldo Carvalho de Melo)
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Use new lsdir() for looking up buildid caches. This changes logic a bit
to ignore all dot files, since the build-id cache must not start with
dot.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160511135217.23943.94596.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Use lsdir() to search in kcore cache directory. This also avoids
checking hidden dot directory entries, because kcore cache directories
must always have the name from timestamps when taking the kcore
snapshots, and it never start with dot.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160511135208.23943.68071.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Use the existing SBUILD_ID_SIZE macro instead of the equivalent
BUILD_ID_SIZE * 2 + 1 expression for allocating a buffer for build-id
strings.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160511135159.23943.57120.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Fix lsdir() to set correct positive error number (ENOMEM).  Since
"errno" must have a positive error number instead of negative number,
fix lsdir to set it correctly.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: e1ce726e ("perf tools: Add lsdir() helper to read a directory")
Link: http://lkml.kernel.org/r/20160511135127.23943.40644.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To reduce the size of builtin-trace.c.

Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/n/tip-ovxifncj34ynrjjseg33lil3@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To reduce the size of builtin-trace.c.

Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/n/tip-c4c47w2a2jx13terl2p2hros@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Debug-frame for remote platforms is not related to the host platform, so
we should test each platform separately.
Signed-off-by: NHe Kuang <hekuang@huawei.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1462866037-30382-5-git-send-email-hekuang@huawei.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Currently only test for local libunwind. We should check all supported
platforms so we can use them to parse perf.data with callchain info on
different machines.
Signed-off-by: NHe Kuang <hekuang@huawei.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1462866037-30382-4-git-send-email-hekuang@huawei.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

When an IP with an unresolved symbol occurs in the callchain more than
once (ie. recursion), then duplicate symbols can be created because
the callchain nodes are never updated after they are first created.

To fix this issue we call dso__find_symbol whenever we encounter a NULL
symbol, in case we already added a symbol at that IP since we started
traversing the callchain.

This change prevents duplicate symbols from being exported when duplicate
IPs are present in the callchain.
Signed-off-by: NChris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462937209-6032-5-git-send-email-cphlipot0@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Remove the call to map_ip() to adjust al.addr, because it has already
been called when assembling the callchain, in:

  thread__resolve_callchain_sample(perf_sample)
      add_callchain_ip(ip = perf_sample->callchain->ips[j])
          thread__find_addr_location(addr = ip)
              thread__find_addr_map(addr) {
                  al->addr = addr
                  if (al->map)
                      al->addr = al->map->map_ip(al->map, al->addr);
              }

Calling it a second time can result in incorrect addresses being used.
This can have effects such as duplicate symbols being created and
exported.
Signed-off-by: NChris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462937209-6032-4-git-send-email-cphlipot0@gmail.com
[ Show the callchain where it is done, to help reviewing this change down the line ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Use the dso__insert_symbol function instead of symbols__insert() in
order to properly update the dso symbol cache.

If the cache is not updated, then duplicate symbols can be
unintentionally created, inserted, and exported.

This change prevents duplicate symbols from being exported due to
dso__find_symbol() using a stale symbol cache.
Signed-off-by: NChris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462937209-6032-3-git-send-email-cphlipot0@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The current method for inserting symbols is to use the symbols__insert()
function. However symbols__insert() does not update the dso symbol
cache.  This causes problems in the following scenario:

1. symbol not found at addr using dso__find_symbol

2. symbol inserted at addr using the existing symbols__insert function

3. symbol still not found at addr using dso__find_symbol() because cache isn't
   updated. This is undesired behavior.

The undesired behavior in (3) is addressed by creating a new function,
dso__insert_symbol() to both insert the symbol and update the symbol
cache if necessary.

If dso__insert_symbol() is used in (2) instead of symbols__insert(),
then the undesired behavior in (3) is avoided.
Signed-off-by: NChris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462937209-6032-2-git-send-email-cphlipot0@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

It probably is equivalent, but that seems to be the "pythonic" way of
dieing? Anyway, one less die() in the tools/perf codebase.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Chris Phlipot <cphlipot0@gmail.com>
Link: http://lkml.kernel.org/n/tip-nlzgepdv2818zs4e7faif9tu@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Merge tag 'perf-core-for-mingo-20160510' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

User visible changes:

- Recording 'dwarf' callchains do not need DWARF unwinding support (He Kuang)

- Print recently added perf_event_attr.write_backward bit flag in -vv
  verbose mode (Arnaldo Carvalho de Melo)

- Fix incorrect python db-export error message in 'perf script' (Chris Phlipot)

- Fix handling of zero-length symbols (Chris Phlipot)

- perf stat: Scale values by unit before metrics (Andi Kleen)

Infrastructure changes:

- Rewrite strbuf not to die(), making tools using it to check its
  return value instead (Masami Hiramatsu)

- Support reading from backward ring buffer, add a 'perf test' entry
  for it (Wang Nan)
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NIngo Molnar <mingo@kernel.org>

The commit b97511c5 ("perf tools: Add overhead/overhead_children
keys defaults via string") moved initialization of column headers but it
missed to check the sort__mode.  As 'perf diff' doesn't call
perf_hpp__init(), the setup_overhead() also should not be called.

Before:

  # Baseline    Delta  Children  Overhead  Shared Object        Symbol
  # ........  .......  ........  ........  ...................  .......................
  #
      28.48%  -28.47%    28.48%    28.48%  [kernel.vmlinux ]    [k] intel_idle
      11.51%  -11.47%    11.51%    11.51%  libxul.so            [.] 0x0000000001a360f7
       3.49%   -3.49%     3.49%     3.49%  [kernel.vmlinux]     [k] generic_exec_single
       2.91%   -2.89%     2.91%     2.91%  libdbus-1.so.3.8.11  [.] 0x000000000000cdc2
       2.86%   -2.85%     2.86%     2.86%  libxcb.so.1.1.0      [.] 0x000000000000c890
       2.44%   -2.39%     2.44%     2.44%  [kernel.vmlinux]     [k] perf_event_aux_ctx

After:

  # Baseline    Delta  Shared Object        Symbol
  # ........  .......  ...................  .......................
  #
      28.48%  -28.47%  [kernel.vmlinux]     [k] intel_idle
      11.51%  -11.47%  libxul.so            [.] 0x0000000001a360f7
       3.49%   -3.49%  [kernel.vmlinux]     [k] generic_exec_single
       2.91%   -2.89%  libdbus-1.so.3.8.11  [.] 0x000000000000cdc2
       2.86%   -2.85%  libxcb.so.1.1.0      [.] 0x000000000000c890
       2.44%   -2.39%  [kernel.vmlinux]     [k] perf_event_aux_ctx
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: <stable@vger.kernel.org> # 4.5+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: b97511c5 ("perf tools: Add overhead/overhead_children keys defaults via string")
Link: http://lkml.kernel.org/r/1462890384-12486-2-git-send-email-acme@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Pull PCI fixes from Bjorn Helgaas:
 "Since v4.5, we've WARNed during resume if a PCI device, including a
  Thunderbolt device, was added while we were suspended.  A change we
  merged for v4.6-rc1 turned that warning into a system hang.  These
  enumeration patches from Lukas Wunner fix this issue:

   - Fix BUG on device attach failure
   - Do not treat EPROBE_DEFER as device attach failure"

* tag 'pci-v4.6-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: Do not treat EPROBE_DEFER as device attach failure
  PCI: Fix BUG on device attach failure

Pull x86 fixes from Ingo Molnar:
 "Two topology corner case fixes, and a MAINTAINERS file update for
  mmiotrace maintenance"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/topology: Set x86_max_cores to 1 for CONFIG_SMP=n
  MAINTAINERS: Add mmiotrace entry
  x86/topology: Handle CPUID bogosity gracefully

Pull scheduler fixes from Ingo Molnar:
 "A UP kernel cpufreq fix and a rt/dl scheduler corner case fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/rt, sched/dl: Don't push if task's scheduling class was changed
  sched/fair: Fix !CONFIG_SMP kernel cpufreq governor breakage

Remove unused xrealloc() and ALLOC_GROW() from libperf.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054801.6158.6204.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Replace ALLOC_GROW with normal realloc code in add_cmd_list() so that it
can handle errors directly.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054752.6158.30562.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Make pmu_formats_string() to check return value of strbuf APIs so that
it can detect errors in it.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054744.6158.37810.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Make topology checkers to check the return value of strbuf APIs so that
it can detect errors in it.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054735.6158.98650.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Make alias handler and sq_quote_argv to check the return value of strbuf
APIs.

In sq_quote_argv() calls die(), but this fix handles strbuf failure as a
special case and returns to caller, since the caller - handle_alias()
also has to check the return value of other strbuf APIs and those checks
can be merged to one if() statement.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054725.6158.84597.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Make check_emacsclient_version() to check the return value of strbuf
APIs so that it can handle errors in strbuf.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054716.6158.11755.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Check the return value of strbuf APIs in perf-probe
related code, so that it can handle errors in strbuf.
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054707.6158.69861.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Rewrite strbuf implementation not to use die() nor xrealloc().  Instead
of die(), now most of the API returns error code or 0 if succeeded.
Suggested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054658.6158.24080.stgit@devboxSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

We got this warning:

    WARNING: CPU: 1 PID: 2468 at kernel/sched/core.c:1161 set_task_cpu+0x1af/0x1c0
    [...]
    Call Trace:

    dump_stack+0x63/0x87
    __warn+0xd1/0xf0
    warn_slowpath_null+0x1d/0x20
    set_task_cpu+0x1af/0x1c0
    push_dl_task.part.34+0xea/0x180
    push_dl_tasks+0x17/0x30
    __balance_callback+0x45/0x5c
    __sched_setscheduler+0x906/0xb90
    SyS_sched_setattr+0x150/0x190
    do_syscall_64+0x62/0x110
    entry_SYSCALL64_slow_path+0x25/0x25

This corresponds to:

    WARN_ON_ONCE(p->state == TASK_RUNNING &&
             p->sched_class == &fair_sched_class &&
             (p->on_rq && !task_on_rq_migrating(p)))

It happens because in find_lock_later_rq(), the task whose scheduling
class was changed to fair class is still pushed away as if it were
a deadline task ...

So, check in find_lock_later_rq() after double_lock_balance(), if the
scheduling class of the deadline task was changed, break and retry.

Apply the same logic to RT tasks.
Signed-off-by: NXunlei Pang <xlpang@redhat.com>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Link: http://lkml.kernel.org/r/1462767091-1215-1-git-send-email-xlpang@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Josef reported that the uncore driver trips over with CONFIG_SMP=n because
x86_max_cores is 16 instead of 12.

The reason is, that for SMP=n the extended topology detection is a NOOP and
the cache leaf is used to determine the number of cores. That's wrong in two
aspects:

1) The cache leaf enumerates the maximum addressable number of cores in the
   package, which is obviously not correct

2) UP has no business with topology bits at all.

Make intel_num_cpu_cores() return 1 for CONFIG_SMP=n
Reported-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team <Kernel-team@fb.com>
Cc: Kan Liang <kan.liang@intel.com>
Link: http://lkml.kernel.org/r/761b4a2a-0332-7954-f030-c6639f949612@fb.com

Pull libnvdimm build fix from Dan Williams:
 "A build fix for the usage of HPAGE_SIZE in the last libnvdimm pull
  request.

  I have taken note that the kbuild robot build success test does not
  include results for alpha_allmodconfig.  Thanks to Guenter for the
  report.  It's tagged for -stable since the original fix will land
  there and cause build problems"

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  libnvdimm, pfn: fix ARCH=alpha allmodconfig build failure

Allowing unprivileged kernel profiling lets any user dump follow kernel
control flow and dump kernel registers.  This most likely allows trivial
kASLR bypassing, and it may allow other mischief as well.  (Off the top
of my head, the PERF_SAMPLE_REGS_INTR output during /dev/urandom reads
could be quite interesting.)
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Merge fixes from Andrew Morton:
 "2 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  zsmalloc: fix zs_can_compact() integer overflow
  Revert "proc/base: make prompt shell start from new line after executing "cat /proc/$pid/wchan""

zs_can_compact() has two race conditions in its core calculation:

unsigned long obj_wasted = zs_stat_get(class, OBJ_ALLOCATED) -
				zs_stat_get(class, OBJ_USED);

1) classes are not locked, so the numbers of allocated and used
   objects can change by the concurrent ops happening on other CPUs
2) shrinker invokes it from preemptible context

Depending on the circumstances, thus, OBJ_ALLOCATED can become
less than OBJ_USED, which can result in either very high or
negative `total_scan' value calculated later in do_shrink_slab().

do_shrink_slab() has some logic to prevent those cases:

 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62
 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62
 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-64
 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62
 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62
 vmscan: shrink_slab: zs_shrinker_scan+0x0/0x28 [zsmalloc] negative objects to delete nr=-62

However, due to the way `total_scan' is calculated, not every
shrinker->count_objects() overflow can be spotted and handled.
To demonstrate the latter, I added some debugging code to do_shrink_slab()
(x86_64) and the results were:

 vmscan: OVERFLOW: shrinker->count_objects() == -1 [18446744073709551615]
 vmscan: but total_scan > 0: 92679974445502
 vmscan: resulting total_scan: 92679974445502
[..]
 vmscan: OVERFLOW: shrinker->count_objects() == -1 [18446744073709551615]
 vmscan: but total_scan > 0: 22634041808232578
 vmscan: resulting total_scan: 22634041808232578

Even though shrinker->count_objects() has returned an overflowed value,
the resulting `total_scan' is positive, and, what is more worrisome, it
is insanely huge. This value is getting used later on in
shrinker->scan_objects() loop:

        while (total_scan >= batch_size ||
               total_scan >= freeable) {
                unsigned long ret;
                unsigned long nr_to_scan = min(batch_size, total_scan);

                shrinkctl->nr_to_scan = nr_to_scan;
                ret = shrinker->scan_objects(shrinker, shrinkctl);
                if (ret == SHRINK_STOP)
                        break;
                freed += ret;

                count_vm_events(SLABS_SCANNED, nr_to_scan);
                total_scan -= nr_to_scan;

                cond_resched();
        }

`total_scan >= batch_size' is true for a very-very long time and
'total_scan >= freeable' is also true for quite some time, because
`freeable < 0' and `total_scan' is large enough, for example,
22634041808232578. The only break condition, in the given scheme of
things, is shrinker->scan_objects() == SHRINK_STOP test, which is a
bit too weak to rely on, especially in heavy zsmalloc-usage scenarios.

To fix the issue, take a pool stat snapshot and use it instead of
racy zs_stat_get() calls.

Link: http://lkml.kernel.org/r/20160509140052.3389-1-sergey.senozhatsky@gmail.comSigned-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>        [4.3+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This reverts the 4.6-rc1 commit 7e2bc81d ("proc/base: make prompt
shell start from new line after executing "cat /proc/$pid/wchan")
because it breaks /proc/$PID/whcan formatting in ps and top.

Revert also because the patch is inconsistent - it adds a newline at the
end of only the '0' wchan, and does not add a newline when
/proc/$PID/wchan contains a symbol name.

eg.
$ ps -eo pid,stat,wchan,comm
PID STAT WCHAN  COMMAND
...
1189 S    -      dbus-launch
1190 Ssl  0
dbus-daemon
1198 Sl   0
lightdm
1299 Ss   ep_pol systemd
1301 S    -      (sd-pam)
1304 Ss   wait   sh
Signed-off-by: NRobin Humble <plaguedbypenguins@gmail.com>
Cc: Minfei Huang <mnfhuang@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This change introduces a fix to symbols__find, so that it is able to
find symbols of length zero (where start == end).

The current code has the following problem:

- The current implementation of symbols__find is unable to find any symbols
  of length zero.

- The db-export framework explicitly creates zero length symbols at
  locations where no symbol currently exists.

The combination of the two above behaviors results in behavior similar
to the example below.

1. addr_location is created for a sample, but symbol is unable to be
   resolved.

2. db export creates an "unknown" symbol of length zero at that address
   and inserts it into the dso.

3. A new sample comes in at the same address, but symbol__find is unable
   to find the zero length symbol, so it is still unresolved.

4. db export sees the symbol is unresolved, and allocated a duplicate
   symbol, even though it already did this in step 2.

This behavior continues every time an address without symbol information
is seen, which causes a very large number of these symbols to be
allocated.

The effect of this fix can be observed by looking at the contents of an
exported database before/after the fix (generated with
scripts/python/export-to-postgresql.py)

Ex.
BEFORE THE CHANGE:

  example_db=# select count(*) from symbols;
   count
  --------
   900213
  (1 row)

  example_db=# select count(*) from symbols where symbols.name='unknown';
   count
  --------
   897355
  (1 row)

  example_db=# select count(*) from symbols where symbols.name!='unknown';
   count
  -------
    2858
  (1 row)

AFTER THE CHANGE:

  example_db=# select count(*) from symbols;
   count
  -------
   25217
  (1 row)

  example_db=# select count(*) from symbols where name='unknown';
   count
  -------
   22359
  (1 row)

  example_db=# select count(*) from symbols where name!='unknown';
   count
  -------
    2858
  (1 row)
Signed-off-by: NChris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462612620-25008-1-git-send-email-cphlipot0@gmail.com
[ Moved the test to later in the rb_tree tests, as this not the likely case ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Now we can see if it is set when using verbose mode in various tools,
such as 'perf test':

  # perf test -vv back
  45: Test backward reading from ring buffer                   :
  --- start ---
  <SNIP>
  ------------------------------------------------------------
  perf_event_attr:
    type                             2
    size                             112
    config                           0x98
    { sample_period, sample_freq }   1
    sample_type                      IP|TID|TIME|CPU|PERIOD|RAW
    disabled                         1
    mmap                             1
    comm                             1
    task                             1
    sample_id_all                    1
    exclude_guest                    1
    mmap2                            1
    comm_exec                        1
    write_backward                   1
  ------------------------------------------------------------
  sys_perf_event_open: pid 20911  cpu -1  group_fd -1  flags 0x8
  <SNIP>
  ---- end ----
  Test backward reading from ring buffer: Ok
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-kxv05kv9qwl5of7rzfeiiwbv@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This test checks reading from backward ring buffer.

Test result:

  # ~/perf test 'ring buffer'
  45: Test backward reading from ring buffer                   : Ok

The test case is a while loop which calls prctl(PR_SET_NAME) multiple
times.  Each prctl should issue 2 events: one PERF_RECORD_SAMPLE, one
PERF_RECORD_COMM.

The first round creates a relative large ring buffer (256 pages). It can
afford all events. Read from it and check the count of each type of
events.

The second round creates a small ring buffer (1 page) and makes it
overwritable. Check the correctness of the buffer.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1462758471-89706-3-git-send-email-wangnan0@huawei.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

perf_evlist__mmap_read_backward() is introduced for reading backward
ring buffer. Since direction for reading such ring buffer is different
from the direction kernel writing to it, and since user need to fetch
most recent record from it, a perf_evlist__mmap_read_catchup() is
introduced to move the reading pointer to the end of the buffer.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1462758471-89706-2-git-send-email-wangnan0@huawei.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Pull crypto fixes from Herbert Xu:
 "This fixes the following issues:

   - bug in ahash SG list walking that may lead to crashes

   - resource leak in qat

   - missing RSA dependency that causes it to fail"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: rsa - select crypto mgr dependency
  crypto: hash - Fix page length clamping in hash walk
  crypto: qat - fix adf_ctl_drv.c:undefined reference to adf_init_pf_wq
  crypto: qat - fix invalid pf2vf_resp_wq logic