linux-stable.git/kernel/trace/trace.c, branch v4.13.3

ring-buffer: Have ring_buffer_alloc_read_page() return error on offline CPU

2017-08-02T18:23:02+00:00

Chunyu Hu reported:
  "per_cpu trace directories and files are created for all possible cpus,
   but only the cpus which have ever been on-lined have their own per cpu
   ring buffer (allocated by cpuhp threads). While trace_buffers_open, the
   open handler for trace file 'trace_pipe_raw' is always trying to access
   field of ring_buffer_per_cpu, and would panic with the NULL pointer.

   Align the behavior of trace_pipe_raw with trace_pipe, that returns -NODEV
   when openning it if that cpu does not have trace ring buffer.

   Reproduce:
   cat /sys/kernel/debug/tracing/per_cpu/cpu31/trace_pipe_raw
   (cpu31 is never on-lined, this is a 16 cores x86_64 box)

   Tested with:
   1) boot with maxcpus=14, read trace_pipe_raw of cpu15.
      Got -NODEV.
   2) oneline cpu15, read trace_pipe_raw of cpu15.
      Get the raw trace data.

   Call trace:
   [ 5760.950995] RIP: 0010:ring_buffer_alloc_read_page+0x32/0xe0
   [ 5760.961678]  tracing_buffers_read+0x1f6/0x230
   [ 5760.962695]  __vfs_read+0x37/0x160
   [ 5760.963498]  ? __vfs_read+0x5/0x160
   [ 5760.964339]  ? security_file_permission+0x9d/0xc0
   [ 5760.965451]  ? __vfs_read+0x5/0x160
   [ 5760.966280]  vfs_read+0x8c/0x130
   [ 5760.967070]  SyS_read+0x55/0xc0
   [ 5760.967779]  do_syscall_64+0x67/0x150
   [ 5760.968687]  entry_SYSCALL64_slow_path+0x25/0x25"

This was introduced by the addition of the feature to reuse reader pages
instead of re-allocating them. The problem is that the allocation of a
reader page (which is per cpu) does not check if the cpu is online and set
up for the ring buffer.

Link: http://lkml.kernel.org/r/1500880866-1177-1-git-send-email-chuhu@redhat.com

Cc: stable@vger.kernel.org
Fixes: 73a757e63114 ("ring-buffer: Return reader page back into existing ring buffer")
Reported-by: Chunyu Hu 
Signed-off-by: Steven Rostedt (VMware)

tracing: Missing error code in tracer_alloc_buffers()

2017-08-02T18:19:57+00:00

If ring_buffer_alloc() or one of the next couple function calls fail
then we should return -ENOMEM but the current code returns success.

Link: http://lkml.kernel.org/r/20170801110201.ajdkct7vwzixahvx@mwanda

Cc: Sebastian Andrzej Siewior 
Cc: Ingo Molnar 
Cc: stable@vger.kernel.org
Fixes: b32614c03413 ('tracing/rb: Convert to hotplug state machine')
Signed-off-by: Dan Carpenter 
Signed-off-by: Steven Rostedt (VMware)

tracing: Call clear_boot_tracer() at lateinit_sync

2017-08-02T18:19:57+00:00

The clear_boot_tracer function is used to reset the default_bootup_tracer
string to prevent it from being accessed after boot, as it originally points
to init data. But since clear_boot_tracer() is called via the
init_lateinit() call, it races with the initcall for registering the hwlat
tracer. If someone adds "ftrace=hwlat" to the kernel command line, depending
on how the linker sets up the text, the saved command line may be cleared,
and the hwlat tracer never is initialized.

Simply have the clear_boot_tracer() be called by initcall_lateinit_sync() as
that's for tasks to be called after lateinit.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=196551

Cc: stable@vger.kernel.org
Fixes: e7c15cd8a ("tracing: Added hardware latency tracer")
Reported-by: Zamir SUN 
Signed-off-by: Steven Rostedt (VMware)

tracing: Fix kmemleak in instance_rmdir

2017-07-20T13:24:25+00:00

Hit the kmemleak when executing instance_rmdir, it forgot releasing
mem of tracing_cpumask. With this fix, the warn does not appear any
more.

unreferenced object 0xffff93a8dfaa7c18 (size 8):
  comm "mkdir", pid 1436, jiffies 4294763622 (age 9134.308s)
  hex dump (first 8 bytes):
    ff ff ff ff ff ff ff ff                          ........
  backtrace:
    [] kmemleak_alloc+0x4a/0xa0
    [] __kmalloc_node+0xf1/0x280
    [] alloc_cpumask_var_node+0x23/0x30
    [] alloc_cpumask_var+0xe/0x10
    [] instance_mkdir+0x90/0x240
    [] tracefs_syscall_mkdir+0x40/0x70
    [] vfs_mkdir+0x109/0x1b0
    [] SyS_mkdir+0xd0/0x100
    [] do_syscall_64+0x67/0x150
    [] return_from_SYSCALL_64+0x0/0x6a
    [] 0xffffffffffffffff

Link: http://lkml.kernel.org/r/1500546969-12594-1-git-send-email-chuhu@redhat.com

Cc: stable@vger.kernel.org
Fixes: ccfe9e42e451 ("tracing: Make tracing_cpumask available for all instances")
Signed-off-by: Chunyu Hu 
Signed-off-by: Steven Rostedt (VMware)

Merge tag 'trace-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2017-07-13T20:17:19+00:00

Pull more tracing updates from Steven Rostedt:
 "A few more minor updates:

   - Show the tgid mappings for user space trace tools to use

   - Fix and optimize the comm and tgid cache recording

   - Sanitize derived kprobe names

   - Ftrace selftest updates

   - trace file header fix

   - Update of Documentation/trace/ftrace.txt

   - Compiler warning fixes

   - Fix possible uninitialized variable"

* tag 'trace-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace: Fix uninitialized variable in match_records()
  ftrace: Remove an unneeded NULL check
  ftrace: Hide cached module code for !CONFIG_MODULES
  tracing: Do note expose stack_trace_filter without DYNAMIC_FTRACE
  tracing: Update Documentation/trace/ftrace.txt
  tracing: Fixup trace file header alignment
  selftests/ftrace: Add a testcase for kprobe event naming
  selftests/ftrace: Add a test to probe module functions
  selftests/ftrace: Update multiple kprobes test for powerpc
  trace/kprobes: Sanitize derived event names
  tracing: Attempt to record other information even if some fail
  tracing: Treat recording tgid for idle task as a success
  tracing: Treat recording comm for idle task as a success
  tracing: Add saved_tgids file to show cached pid to tgid mappings

tracing: Fixup trace file header alignment

2017-07-11T20:48:19+00:00

The addition of TGID to the tracing header added a check to see if TGID
shoudl be displayed or not, and updated the header accordingly.
Unfortunately, it broke the default header.

Also add constant strings to use for spacing. This does remove the
visibility of the header a bit, but cuts it down from the extended lines
much greater than 80 characters.

Before this change:

 # tracer: function
 #
 #                            _-----=> irqs-off
 #                           / _----=> need-resched
 #                          | / _---=> hardirq/softirq
 #                          || / _--=> preempt-depth
 #                          ||| /     delay
 #           TASK-PID   CPU#||||    TIMESTAMP  FUNCTION
 #              | |       | ||||       |         |
        swapper/0-1     [000] ....     0.277830: migration_init <-do_one_initcall
        swapper/0-1     [002] d...    13.861967: Unknown type 1201
        swapper/0-1     [002] d..1    13.861970: Unknown type 1202

After this change:

 # tracer: function
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
        swapper/0-1     [000] ....     0.278245: migration_init <-do_one_initcall
        swapper/0-1     [003] d...    13.861189: Unknown type 1201
        swapper/0-1     [003] d..1    13.861192: Unknown type 1202

Cc: Joel Fernandes 
Fixes: 441dae8f2f29 ("tracing: Add support for display of tgid in trace output")
Signed-off-by: Steven Rostedt (VMware)

Merge tag 'linux-kselftest-4.13-rc1-update' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2017-07-07T21:04:47+00:00

Pull Kselftest updates from Shuah Khan:
 "This update consists of:

   - TAP13 framework and changes to some tests to convert to TAP13.
     Converting kselftest output to standard format will help identify
     run to run differences and pin point failures easily. TAP13 format
     has been in use for several years and the output is human friendly.

     Please find the specification:
       https://testanything.org/tap-version-13-specification.html

     Credit goes to Tim Bird for recommending TAP13 as a suitable
     format, and to Grag KH for kick starting the work with help from
     Paul Elder and Alice Ferrazzi

     The first phase of the TAp13 conversion is included in this update.
     Future updates will include updates to rest of the tests.

   - Masami Hiramatsu fixed ftrace to run on 4.9 stable kernels.

   - Kselftest documnetation has been converted to ReST format. Document
     now has a new home under Documentation/dev-tools.

   - kselftest_harness.h is now available for general use as a result of
     Mickaël Salaün's work.

   - Several fixes to skip and/or fail tests gracefully on older
     releases"

* tag 'linux-kselftest-4.13-rc1-update' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (48 commits)
  selftests: membarrier: use ksft_* var arg msg api
  selftests: breakpoints: breakpoint_test_arm64: convert test to use TAP13
  selftests: breakpoints: step_after_suspend_test use ksft_* var arg msg api
  selftests: breakpoint_test: use ksft_* var arg msg api
  kselftest: add ksft_print_msg() function to output general information
  kselftest: make ksft_* output functions variadic
  selftests/capabilities: Fix the test_execve test
  selftests: intel_pstate: add .gitignore
  selftests: fix memory-hotplug test
  selftests: add missing test name in memory-hotplug test
  selftests: check percentage range for memory-hotplug test
  selftests: check hot-pluggagble memory for memory-hotplug test
  selftests: typo correction for memory-hotplug test
  selftests: ftrace: Use md5sum to take less time of checking logs
  tools/testing/selftests/sysctl: Add pre-check to the value of writes_strict
  kselftest.rst: do some adjustments after ReST conversion
  selftest/net/Makefile: Specify output with $(OUTPUT)
  selftest/intel_pstate/aperf: Use LDLIBS instead of LDFLAGS
  selftest/memfd/Makefile: Fix build error
  selftests: lib: Skip tests on missing test modules
  ...

tracing: Attempt to record other information even if some fail

2017-07-07T13:11:34+00:00

In recent patches where we record comm and tgid at the same time, we skip
continuing to record if any fail. Fix that by trying to record as many things
as we can even if some couldn't be recorded. If any information isn't recorded,
then we don't set trace_taskinfo_save as before.

Link: http://lkml.kernel.org/r/20170706230023.17942-3-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar 
Signed-off-by: Joel Fernandes 
Signed-off-by: Steven Rostedt (VMware)

tracing: Treat recording tgid for idle task as a success

2017-07-07T13:04:23+00:00

Currently we stop recording tgid for non-idle tasks when switching from/to idle
task since we treat that as a record failure. Fix that by treat recording of
tgid for idle task as a success.

Link: http://lkml.kernel.org/r/20170706230023.17942-2-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar 
Reported-by: Michael Sartain 
Signed-off-by: Joel Fernandes 
Signed-off-by: Steven Rostedt (VMware)

tracing: Treat recording comm for idle task as a success

2017-07-07T13:04:14+00:00

Currently we stop recording comm for non-idle tasks when switching from/to idle
task since we treat that as a record failure. Fix that by treat recording of
comm for idle task as a success.

Link: http://lkml.kernel.org/r/20170706230023.17942-1-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar 
Reported-by: Michael Sartain 
Signed-off-by: Joel Fernandes 
Signed-off-by: Steven Rostedt (VMware)