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linux/kernel/trace
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Steven Rostedt (VMware) 785e3c0a3a tracing: Map all PIDs to command lines 
The default max PID is set by PID_MAX_DEFAULT, and the tracing
infrastructure uses this number to map PIDs to the comm names of the
tasks, such output of the trace can show names from the recorded PIDs in
the ring buffer. This mapping is also exported to user space via the
"saved_cmdlines" file in the tracefs directory.

But currently the mapping expects the PIDs to be less than
PID_MAX_DEFAULT, which is the default maximum and not the real maximum.
Recently, systemd will increases the maximum value of a PID on the system,
and when tasks are traced that have a PID higher than PID_MAX_DEFAULT, its
comm is not recorded. This leads to the entire trace to have "<...>" as
the comm name, which is pretty useless.

Instead, keep the array mapping the size of PID_MAX_DEFAULT, but instead
of just mapping the index to the comm, map a mask of the PID
(PID_MAX_DEFAULT - 1) to the comm, and find the full PID from the
map_cmdline_to_pid array (that already exists).

This bug goes back to the beginning of ftrace, but hasn't been an issue
until user space started increasing the maximum value of PIDs.

Link: https://lkml.kernel.org/r/20210427113207.3c601884@gandalf.local.home

Cc: stable@vger.kernel.org
Fixes: bc0c38d139 ("ftrace: latency tracer infrastructure")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-04-28 13:20:04 -04:00
..
blktrace.c block-5.12-2021-02-27 2021-02-28 11:23:38 -08:00
bpf_trace.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
bpf_trace.h bpf: Use dedicated bpf_trace_printk event instead of trace_printk() 2020-07-13 16:55:49 -07:00
error_report-traces.c tracing: add error_report_end trace point 2021-02-26 09:41:02 -08:00
fgraph.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
ftrace.c ftrace: Simplify the calculation of page number for ftrace_page->records some more 2021-04-01 16:56:47 -04:00
ftrace_internal.h x86/ftrace: Have ftrace trampolines turn read-only at the end of system boot up 2020-05-12 18:24:34 -04:00
Kconfig tracing: Fix help text of TRACEPOINT_BENCHMARK in Kconfig 2021-03-04 09:45:17 -05:00
kprobe_event_gen_test.c tracing: Add kprobe event command generation test module 2020-01-30 09:46:28 -05:00
Makefile tracing: add error_report_end trace point 2021-02-26 09:41:02 -08:00
power-traces.c
preemptirq_delay_test.c kernel: trace: preemptirq_delay_test: add cpu affinity 2021-02-02 17:02:07 -05:00
ring_buffer.c tracing: Remove unused argument from "ring_buffer_time_stamp() 2021-04-01 14:18:32 -04:00
ring_buffer_benchmark.c sched,tracing: Convert to sched_set_fifo() 2020-07-29 11:43:53 +02:00
rpm-traces.c
synth_event_gen_test.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace.c tracing: Map all PIDs to command lines 2021-04-28 13:20:04 -04:00
trace.h tracing: Add method for recording "func_repeats" events 2021-04-15 14:50:02 -04:00
trace_benchmark.c tracing: Fix some typos in comments 2020-11-10 20:39:40 -05:00
trace_benchmark.h
trace_boot.c tracing: Disable ftrace selftests when any tracer is running 2020-12-14 12:05:03 -05:00
trace_branch.c tracing: Merge irqflags + preempt counter. 2021-02-02 17:02:06 -05:00
trace_clock.c
trace_dynevent.c tracing/dynevent: Delegate parsing to create function 2021-02-09 12:52:15 -05:00
trace_dynevent.h tracing/dynevent: Delegate parsing to create function 2021-02-09 12:52:15 -05:00
trace_entries.h tracing: Define new ftrace event "func_repeats" 2021-04-15 14:50:01 -04:00
trace_event_perf.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_events.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_events_filter.c tracing: Update create_system_filter() kernel-doc comment 2021-03-25 16:04:35 -04:00
trace_events_filter_test.h
trace_events_hist.c tracing: Use a no_filter_buffering_ref to stop using the filter buffer 2021-03-18 12:58:26 -04:00
trace_events_inject.c tracing: Merge irqflags + preempt counter. 2021-02-02 17:02:06 -05:00
trace_events_synth.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_events_trigger.c tracing: Pass buffer of event to trigger operations 2021-03-18 12:58:26 -04:00
trace_export.c tracing: Fix some typos in comments 2020-11-10 20:39:40 -05:00
trace_functions.c tracing: Add "func_no_repeats" option for function tracing 2021-04-15 14:50:02 -04:00
trace_functions_graph.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_hwlat.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_irqsoff.c tracing: Merge irqflags + preempt counter. 2021-02-02 17:02:06 -05:00
trace_kdb.c tracing: Rename trace_buffer to array_buffer 2020-01-13 13:19:38 -05:00
trace_kprobe.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_kprobe_selftest.c
trace_kprobe_selftest.h
trace_mmiotrace.c tracing: Remove definition of DEBUG in trace_mmiotrace.c 2021-02-02 17:02:07 -05:00
trace_nop.c
trace_output.c ftrace: Reuse the output of the function tracer for func_repeats 2021-04-15 16:34:26 -04:00
trace_output.h ftrace: Add recording of functions that caused recursion 2020-11-06 08:42:26 -05:00
trace_preemptirq.c lockdep: fix order in trace_hardirqs_off_caller() 2020-09-14 10:08:07 +02:00
trace_printk.c tracing: Add a verifier to check string pointers for trace events 2021-03-18 12:58:27 -04:00
trace_probe.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_probe.h tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_probe_tmpl.h tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_recursion_record.c ftrace: Add recording of functions that caused recursion 2020-11-06 08:42:26 -05:00
trace_sched_switch.c tracing: Fix sched switch start/stop refcount racy updates 2020-01-30 09:46:10 -05:00
trace_sched_wakeup.c tracing: Merge irqflags + preempt counter. 2021-02-02 17:02:06 -05:00
trace_selftest.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_selftest_dynamic.c
trace_seq.c tracing: Fix various typos in comments 2021-03-23 14:08:18 -04:00
trace_stack.c ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs 2020-11-13 12:14:55 -05:00
trace_stat.c tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer 2020-09-18 22:17:14 -04:00
trace_stat.h tracing: Use generic type for comparator function 2019-11-14 13:15:11 -05:00
trace_synth.h tracing: Add support for dynamic strings to synthetic events 2020-10-05 19:32:18 -04:00
trace_syscalls.c tracing: Merge irqflags + preempt counter. 2021-02-02 17:02:06 -05:00
trace_uprobe.c tracing/dynevent: Delegate parsing to create function 2021-02-09 12:52:15 -05:00
tracing_map.c tracing: Fix some typos in comments 2020-11-10 20:39:40 -05:00
tracing_map.h tracing: Fix some typos in comments 2020-11-10 20:39:40 -05:00