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  1. 13 10月, 2017 1 次提交
  3. 11 10月, 2017 2 次提交
  5. 07 10月, 2017 1 次提交
  7. 06 10月, 2017 4 次提交
    • S
      ftrace/kallsyms: Have /proc/kallsyms show saved mod init functions · 6171a031
      由 Steven Rostedt (VMware) 提交于 
      If a module is loaded while tracing is enabled, then there's a possibility
that the module init functions were traced. These functions have their name
and address stored by ftrace such that it can translate the function address
that is written into the buffer into a human readable function name.

As userspace tools may be doing the same, they need a way to map function
names to their address as well. This is done through reading /proc/kallsyms.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      6171a031
    • S
      ftrace: Add freeing algorithm to free ftrace_mod_maps · 6aa69784
      由 Steven Rostedt (VMware) 提交于 
      The ftrace_mod_map is a descriptor to save module init function names in
case they were traced, and the trace output needs to reference the function
name from the function address. But after the function is unloaded, it
the maps should be freed, as the rest of the function names are as well.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      6aa69784
    • S
      ftrace: Save module init functions kallsyms symbols for tracing · aba4b5c2
      由 Steven Rostedt (VMware) 提交于 
      If function tracing is active when the module init functions are freed, then
store them to be referenced by kallsyms. As module init functions can now be
traced on module load, they were useless:

 ># echo ':mod:snd_seq' > set_ftrace_filter
 ># echo function > current_tracer
 ># modprobe snd_seq
 ># cat trace
 # tracer: function
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
         modprobe-2786  [000] ....  3189.037874: 0xffffffffa0860000 <-do_one_initcall
         modprobe-2786  [000] ....  3189.037876: 0xffffffffa086004d <-0xffffffffa086000f
         modprobe-2786  [000] ....  3189.037876: 0xffffffffa086010d <-0xffffffffa0860018
         modprobe-2786  [000] ....  3189.037877: 0xffffffffa086011a <-0xffffffffa0860021
         modprobe-2786  [000] ....  3189.037877: 0xffffffffa0860080 <-0xffffffffa086002a
         modprobe-2786  [000] ....  3189.039523: 0xffffffffa0860400 <-0xffffffffa0860033
         modprobe-2786  [000] ....  3189.039523: 0xffffffffa086038a <-0xffffffffa086041c
         modprobe-2786  [000] ....  3189.039591: 0xffffffffa086038a <-0xffffffffa0860436
         modprobe-2786  [000] ....  3189.039657: 0xffffffffa086038a <-0xffffffffa0860450
         modprobe-2786  [000] ....  3189.039719: 0xffffffffa0860127 <-0xffffffffa086003c
         modprobe-2786  [000] ....  3189.039742: snd_seq_create_kernel_client <-0xffffffffa08601f6

When the output is shown, the kallsyms for the module init functions have
already been freed, and the output of the trace can not convert them to
their function names.

Now this looks like this:

 # tracer: function
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
         modprobe-2463  [002] ....   174.243237: alsa_seq_init <-do_one_initcall
         modprobe-2463  [002] ....   174.243239: client_init_data <-alsa_seq_init
         modprobe-2463  [002] ....   174.243240: snd_sequencer_memory_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.243240: snd_seq_queues_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.243240: snd_sequencer_device_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.244860: snd_seq_info_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.244861: create_info_entry <-snd_seq_info_init
         modprobe-2463  [002] ....   174.244936: create_info_entry <-snd_seq_info_init
         modprobe-2463  [002] ....   174.245003: create_info_entry <-snd_seq_info_init
         modprobe-2463  [002] ....   174.245072: snd_seq_system_client_init <-alsa_seq_init
         modprobe-2463  [002] ....   174.245094: snd_seq_create_kernel_client <-snd_seq_system_client_init
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      aba4b5c2
    • S
      ftrace: Allow module init functions to be traced · 3e234289
      由 Steven Rostedt (VMware) 提交于 
      Allow for module init sections to be traced as well as core kernel init
sections. Now that filtering modules functions can be stored, for when they
are loaded, it makes sense to be able to trace them.

Cc: Jessica Yu <jeyu@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      3e234289
  9. 05 10月, 2017 8 次提交
  11. 04 10月, 2017 4 次提交
  13. 29 9月, 2017 1 次提交
  15. 25 9月, 2017 1 次提交
    • W
      blktrace: Fix potential deadlock between delete & sysfs ops · 5acb3cc2
      由 Waiman Long 提交于 
      The lockdep code had reported the following unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(s_active#228);
                               lock(&bdev->bd_mutex/1);
                               lock(s_active#228);
  lock(&bdev->bd_mutex);

 *** DEADLOCK ***

The deadlock may happen when one task (CPU1) is trying to delete a
partition in a block device and another task (CPU0) is accessing
tracing sysfs file (e.g. /sys/block/dm-1/trace/act_mask) in that
partition.

The s_active isn't an actual lock. It is a reference count (kn->count)
on the sysfs (kernfs) file. Removal of a sysfs file, however, require
a wait until all the references are gone. The reference count is
treated like a rwsem using lockdep instrumentation code.

The fact that a thread is in the sysfs callback method or in the
ioctl call means there is a reference to the opended sysfs or device
file. That should prevent the underlying block structure from being
removed.

Instead of using bd_mutex in the block_device structure, a new
blk_trace_mutex is now added to the request_queue structure to protect
access to the blk_trace structure.
Suggested-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NWaiman Long <longman@redhat.com>
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Fix typo in patch subject line, and prune a comment detailing how
the code used to work.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      5acb3cc2
  17. 24 9月, 2017 1 次提交
  19. 20 9月, 2017 3 次提交
  21. 14 9月, 2017 1 次提交
    • M
      mm: treewide: remove GFP_TEMPORARY allocation flag · 0ee931c4
      由 Michal Hocko 提交于 
      GFP_TEMPORARY was introduced by commit e12ba74d ("Group short-lived
and reclaimable kernel allocations") along with __GFP_RECLAIMABLE.  It's
primary motivation was to allow users to tell that an allocation is
short lived and so the allocator can try to place such allocations close
together and prevent long term fragmentation.  As much as this sounds
like a reasonable semantic it becomes much less clear when to use the
highlevel GFP_TEMPORARY allocation flag.  How long is temporary? Can the
context holding that memory sleep? Can it take locks? It seems there is
no good answer for those questions.

The current implementation of GFP_TEMPORARY is basically GFP_KERNEL |
__GFP_RECLAIMABLE which in itself is tricky because basically none of
the existing caller provide a way to reclaim the allocated memory.  So
this is rather misleading and hard to evaluate for any benefits.

I have checked some random users and none of them has added the flag
with a specific justification.  I suspect most of them just copied from
other existing users and others just thought it might be a good idea to
use without any measuring.  This suggests that GFP_TEMPORARY just
motivates for cargo cult usage without any reasoning.

I believe that our gfp flags are quite complex already and especially
those with highlevel semantic should be clearly defined to prevent from
confusion and abuse.  Therefore I propose dropping GFP_TEMPORARY and
replace all existing users to simply use GFP_KERNEL.  Please note that
SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and
so they will be placed properly for memory fragmentation prevention.

I can see reasons we might want some gfp flag to reflect shorterm
allocations but I propose starting from a clear semantic definition and
only then add users with proper justification.

This was been brought up before LSF this year by Matthew [1] and it
turned out that GFP_TEMPORARY really doesn't have a clear semantic.  It
seems to be a heuristic without any measured advantage for most (if not
all) its current users.  The follow up discussion has revealed that
opinions on what might be temporary allocation differ a lot between
developers.  So rather than trying to tweak existing users into a
semantic which they haven't expected I propose to simply remove the flag
and start from scratch if we really need a semantic for short term
allocations.

[1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org

[akpm@linux-foundation.org: fix typo]
[akpm@linux-foundation.org: coding-style fixes]
[sfr@canb.auug.org.au: drm/i915: fix up]
  Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Neil Brown <neilb@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0ee931c4
  23. 12 9月, 2017 1 次提交
  25. 09 9月, 2017 1 次提交
  27. 07 9月, 2017 1 次提交
  29. 06 9月, 2017 1 次提交
  31. 05 9月, 2017 1 次提交
    • S
      tracing: Add barrier to trace_printk() buffer nesting modification · 3d9622c1
      由 Steven Rostedt (VMware) 提交于 
      trace_printk() uses 4 buffers, one for each context (normal, softirq, irq
and NMI), such that it does not need to worry about one context preempting
the other. There's a nesting counter that gets incremented to figure out
which buffer to use. If the context gets preempted by another context which
calls trace_printk() it will increment the counter and use the next buffer,
and restore the counter when it is finished.

The problem is that gcc may optimize the modification of the buffer nesting
counter and it may not be incremented in memory before the buffer is used.
If this happens, and the context gets interrupted by another context, it
could pick the same buffer and corrupt the one that is being used.

Compiler barriers need to be added after the nesting variable is incremented
and before it is decremented to prevent usage of the context buffers by more
than one context at the same time.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: stable@vger.kernel.org
Fixes: e2ace001 ("tracing: Choose static tp_printk buffer by explicit nesting count")
Hat-tip-to: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      3d9622c1
  33. 02 9月, 2017 2 次提交
    • S
      ftrace: Fix memleak when unregistering dynamic ops when tracing disabled · edb096e0
      由 Steven Rostedt (VMware) 提交于 
      If function tracing is disabled by the user via the function-trace option or
the proc sysctl file, and a ftrace_ops that was allocated on the heap is
unregistered, then the shutdown code exits out without doing the proper
clean up. This was found via kmemleak and running the ftrace selftests, as
one of the tests unregisters with function tracing disabled.

 # cat kmemleak
unreferenced object 0xffffffffa0020000 (size 4096):
  comm "swapper/0", pid 1, jiffies 4294668889 (age 569.209s)
  hex dump (first 32 bytes):
    55 ff 74 24 10 55 48 89 e5 ff 74 24 18 55 48 89  U.t$.UH...t$.UH.
    e5 48 81 ec a8 00 00 00 48 89 44 24 50 48 89 4c  .H......H.D$PH.L
  backtrace:
    [<ffffffff81d64665>] kmemleak_vmalloc+0x85/0xf0
    [<ffffffff81355631>] __vmalloc_node_range+0x281/0x3e0
    [<ffffffff8109697f>] module_alloc+0x4f/0x90
    [<ffffffff81091170>] arch_ftrace_update_trampoline+0x160/0x420
    [<ffffffff81249947>] ftrace_startup+0xe7/0x300
    [<ffffffff81249bd2>] register_ftrace_function+0x72/0x90
    [<ffffffff81263786>] trace_selftest_ops+0x204/0x397
    [<ffffffff82bb8971>] trace_selftest_startup_function+0x394/0x624
    [<ffffffff81263a75>] run_tracer_selftest+0x15c/0x1d7
    [<ffffffff82bb83f1>] init_trace_selftests+0x75/0x192
    [<ffffffff81002230>] do_one_initcall+0x90/0x1e2
    [<ffffffff82b7d620>] kernel_init_freeable+0x350/0x3fe
    [<ffffffff81d61ec3>] kernel_init+0x13/0x122
    [<ffffffff81d72c6a>] ret_from_fork+0x2a/0x40
    [<ffffffffffffffff>] 0xffffffffffffffff

Cc: stable@vger.kernel.org
Fixes: 12cce594 ("ftrace/x86: Allow !CONFIG_PREEMPT dynamic ops to use allocated trampolines")
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      edb096e0
    • S
      ftrace: Fix selftest goto location on error · 46320a6a
      由 Steven Rostedt (VMware) 提交于 
      In the second iteration of trace_selftest_ops(), the error goto label is
wrong in the case where trace_selftest_test_global_cnt is off. In the
case of error, it leaks the dynamic ops that was allocated.

Cc: stable@vger.kernel.org
Fixes: 95950c2e ("ftrace: Add self-tests for multiple function trace users")
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      46320a6a
  35. 01 9月, 2017 2 次提交
    • S
      ftrace: Zero out ftrace hashes when a module is removed · 2a5bfe47
      由 Steven Rostedt (VMware) 提交于 
      When a ftrace filter has a module function, and that module is removed, the
filter still has its address as being enabled. This can cause interesting
side effects. Nothing dangerous, but unwanted functions can be traced
because of it.

 # cd /sys/kernel/tracing
 # echo ':mod:snd_seq' > set_ftrace_filter
 # cat set_ftrace_filter
snd_use_lock_sync_helper [snd_seq]
check_event_type_and_length [snd_seq]
snd_seq_ioctl_pversion [snd_seq]
snd_seq_ioctl_client_id [snd_seq]
snd_seq_ioctl_get_queue_tempo [snd_seq]
update_timestamp_of_queue [snd_seq]
snd_seq_ioctl_get_queue_status [snd_seq]
snd_seq_set_queue_tempo [snd_seq]
snd_seq_ioctl_set_queue_tempo [snd_seq]
snd_seq_ioctl_get_queue_timer [snd_seq]
seq_free_client1 [snd_seq]
[..]
 # rmmod snd_seq
 # cat set_ftrace_filter

 # modprobe kvm
 # cat set_ftrace_filter
kvm_set_cr4 [kvm]
kvm_emulate_hypercall [kvm]
kvm_set_dr [kvm]

This is because removing the snd_seq module after it was being filtered,
left the address of the snd_seq functions in the hash. When the kvm module
was loaded, some of its functions were loaded at the same address as the
snd_seq module. This would enable them to be filtered and traced.

Now we don't want to clear the hash completely. That would cause removing a
module where only its functions are filtered, to cause the tracing to enable
all functions, as an empty filter means to trace all functions. Instead,
just set the hash ip address to zero. Then it will never match any function.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      2a5bfe47
    • S
      tracing: Only have rmmod clear buffers that its events were active in · 065e63f9
      由 Steven Rostedt (VMware) 提交于 
      Currently, when a module event is enabled, when that module is removed, it
clears all ring buffers. This is to prevent another module from being loaded
and having one of its trace event IDs from reusing a trace event ID of the
removed module. This could cause undesirable effects as the trace event of
the new module would be using its own processing algorithms to process raw
data of another event. To prevent this, when a module is loaded, if any of
its events have been used (signified by the WAS_ENABLED event call flag,
which is never cleared), all ring buffers are cleared, just in case any one
of them contains event data of the removed event.

The problem is, there's no reason to clear all ring buffers if only one (or
less than all of them) uses one of the events. Instead, only clear the ring
buffers that recorded the events of a module that is being removed.

To do this, instead of keeping the WAS_ENABLED flag with the trace event
call, move it to the per instance (per ring buffer) event file descriptor.
The event file descriptor maps each event to a separate ring buffer
instance. Then when the module is removed, only the ring buffers that
activated one of the module's events get cleared. The rest are not touched.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      065e63f9
  37. 29 8月, 2017 1 次提交
    • Z
      perf/ftrace: Fix double traces of perf on ftrace:function · 75e83876
      由 Zhou Chengming 提交于 
      When running perf on the ftrace:function tracepoint, there is a bug
which can be reproduced by:

  perf record -e ftrace:function -a sleep 20 &
  perf record -e ftrace:function ls
  perf script

              ls 10304 [005]   171.853235: ftrace:function:
  perf_output_begin
              ls 10304 [005]   171.853237: ftrace:function:
  perf_output_begin
              ls 10304 [005]   171.853239: ftrace:function:
  task_tgid_nr_ns
              ls 10304 [005]   171.853240: ftrace:function:
  task_tgid_nr_ns
              ls 10304 [005]   171.853242: ftrace:function:
  __task_pid_nr_ns
              ls 10304 [005]   171.853244: ftrace:function:
  __task_pid_nr_ns

We can see that all the function traces are doubled.

The problem is caused by the inconsistency of the register
function perf_ftrace_event_register() with the probe function
perf_ftrace_function_call(). The former registers one probe
for every perf_event. And the latter handles all perf_events
on the current cpu. So when two perf_events on the current cpu,
the traces of them will be doubled.

So this patch adds an extra parameter "event" for perf_tp_event,
only send sample data to this event when it's not NULL.
Signed-off-by: NZhou Chengming <zhouchengming1@huawei.com>
Reviewed-by: NJiri Olsa <jolsa@kernel.org>
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: alexander.shishkin@linux.intel.com
Cc: huawei.libin@huawei.com
Link: http://lkml.kernel.org/r/1503668977-12526-1-git-send-email-zhouchengming1@huawei.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      75e83876
  39. 24 8月, 2017 3 次提交
    • S
      tracing: Fix freeing of filter in create_filter() when set_str is false · 8b0db1a5
      由 Steven Rostedt (VMware) 提交于 
      Performing the following task with kmemleak enabled:

 # cd /sys/kernel/tracing/events/irq/irq_handler_entry/
 # echo 'enable_event:kmem:kmalloc:3 if irq >' > trigger
 # echo 'enable_event:kmem:kmalloc:3 if irq > 31' > trigger
 # echo scan > /sys/kernel/debug/kmemleak
 # cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff8800b9290308 (size 32):
  comm "bash", pid 1114, jiffies 4294848451 (age 141.139s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff81cef5aa>] kmemleak_alloc+0x4a/0xa0
    [<ffffffff81357938>] kmem_cache_alloc_trace+0x158/0x290
    [<ffffffff81261c09>] create_filter_start.constprop.28+0x99/0x940
    [<ffffffff812639c9>] create_filter+0xa9/0x160
    [<ffffffff81263bdc>] create_event_filter+0xc/0x10
    [<ffffffff812655e5>] set_trigger_filter+0xe5/0x210
    [<ffffffff812660c4>] event_enable_trigger_func+0x324/0x490
    [<ffffffff812652e2>] event_trigger_write+0x1a2/0x260
    [<ffffffff8138cf87>] __vfs_write+0xd7/0x380
    [<ffffffff8138f421>] vfs_write+0x101/0x260
    [<ffffffff8139187b>] SyS_write+0xab/0x130
    [<ffffffff81cfd501>] entry_SYSCALL_64_fastpath+0x1f/0xbe
    [<ffffffffffffffff>] 0xffffffffffffffff

The function create_filter() is passed a 'filterp' pointer that gets
allocated, and if "set_str" is true, it is up to the caller to free it, even
on error. The problem is that the pointer is not freed by create_filter()
when set_str is false. This is a bug, and it is not up to the caller to free
the filter on error if it doesn't care about the string.

Link: http://lkml.kernel.org/r/1502705898-27571-2-git-send-email-chuhu@redhat.com

Cc: stable@vger.kernel.org
Fixes: 38b78eb8 ("tracing: Factorize filter creation")
Reported-by: NChunyu Hu <chuhu@redhat.com>
Tested-by: NChunyu Hu <chuhu@redhat.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      8b0db1a5
    • C
      tracing: Fix kmemleak in tracing_map_array_free() · 475bb3c6
      由 Chunyu Hu 提交于 
      kmemleak reported the below leak when I was doing clear of the hist
trigger. With this patch, the kmeamleak is gone.

unreferenced object 0xffff94322b63d760 (size 32):
  comm "bash", pid 1522, jiffies 4403687962 (age 2442.311s)
  hex dump (first 32 bytes):
    00 01 00 00 04 00 00 00 08 00 00 00 ff 00 00 00  ................
    10 00 00 00 00 00 00 00 80 a8 7a f2 31 94 ff ff  ..........z.1...
  backtrace:
    [<ffffffff9e96c27a>] kmemleak_alloc+0x4a/0xa0
    [<ffffffff9e424cba>] kmem_cache_alloc_trace+0xca/0x1d0
    [<ffffffff9e377736>] tracing_map_array_alloc+0x26/0x140
    [<ffffffff9e261be0>] kretprobe_trampoline+0x0/0x50
    [<ffffffff9e38b935>] create_hist_data+0x535/0x750
    [<ffffffff9e38bd47>] event_hist_trigger_func+0x1f7/0x420
    [<ffffffff9e38893d>] event_trigger_write+0xfd/0x1a0
    [<ffffffff9e44dfc7>] __vfs_write+0x37/0x170
    [<ffffffff9e44f552>] vfs_write+0xb2/0x1b0
    [<ffffffff9e450b85>] SyS_write+0x55/0xc0
    [<ffffffff9e203857>] do_syscall_64+0x67/0x150
    [<ffffffff9e977ce7>] return_from_SYSCALL_64+0x0/0x6a
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff9431f27aa880 (size 128):
  comm "bash", pid 1522, jiffies 4403687962 (age 2442.311s)
  hex dump (first 32 bytes):
    00 00 8c 2a 32 94 ff ff 00 f0 8b 2a 32 94 ff ff  ...*2......*2...
    00 e0 8b 2a 32 94 ff ff 00 d0 8b 2a 32 94 ff ff  ...*2......*2...
  backtrace:
    [<ffffffff9e96c27a>] kmemleak_alloc+0x4a/0xa0
    [<ffffffff9e425348>] __kmalloc+0xe8/0x220
    [<ffffffff9e3777c1>] tracing_map_array_alloc+0xb1/0x140
    [<ffffffff9e261be0>] kretprobe_trampoline+0x0/0x50
    [<ffffffff9e38b935>] create_hist_data+0x535/0x750
    [<ffffffff9e38bd47>] event_hist_trigger_func+0x1f7/0x420
    [<ffffffff9e38893d>] event_trigger_write+0xfd/0x1a0
    [<ffffffff9e44dfc7>] __vfs_write+0x37/0x170
    [<ffffffff9e44f552>] vfs_write+0xb2/0x1b0
    [<ffffffff9e450b85>] SyS_write+0x55/0xc0
    [<ffffffff9e203857>] do_syscall_64+0x67/0x150
    [<ffffffff9e977ce7>] return_from_SYSCALL_64+0x0/0x6a
    [<ffffffffffffffff>] 0xffffffffffffffff

Link: http://lkml.kernel.org/r/1502705898-27571-1-git-send-email-chuhu@redhat.com

Cc: stable@vger.kernel.org
Fixes: 08d43a5f ("tracing: Add lock-free tracing_map")
Signed-off-by: NChunyu Hu <chuhu@redhat.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      475bb3c6
    • S
      ftrace: Check for null ret_stack on profile function graph entry function · a8f0f9e4
      由 Steven Rostedt (VMware) 提交于 
      There's a small race when function graph shutsdown and the calling of the
registered function graph entry callback. The callback must not reference
the task's ret_stack without first checking that it is not NULL. Note, when
a ret_stack is allocated for a task, it stays allocated until the task exits.
The problem here, is that function_graph is shutdown, and a new task was
created, which doesn't have its ret_stack allocated. But since some of the
functions are still being traced, the callbacks can still be called.

The normal function_graph code handles this, but starting with commit
8861dd30 ("ftrace: Access ret_stack->subtime only in the function
profiler") the profiler code references the ret_stack on function entry, but
doesn't check if it is NULL first.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=196611

Cc: stable@vger.kernel.org
Fixes: 8861dd30 ("ftrace: Access ret_stack->subtime only in the function profiler")
Reported-by: lilydjwg@gmail.com
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
      a8f0f9e4