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7717c6be69
While cleaning the stacktrace code I unintentially changed the skip depth of
trace_buffer_unlock_commit_regs() from 0 to 6. kprobes uses this function,
and with skipping 6 call backs, it can easily produce no stack.
Here's how I tested it:
# echo 'p:ext4_sync_fs ext4_sync_fs ' > /sys/kernel/debug/tracing/kprobe_events
# echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable
# cat /sys/kernel/debug/trace
sync-2394 [005] 502.457060: ext4_sync_fs: (ffffffff81317650)
sync-2394 [005] 502.457063: kernel_stack: <stack trace>
sync-2394 [005] 502.457086: ext4_sync_fs: (ffffffff81317650)
sync-2394 [005] 502.457087: kernel_stack: <stack trace>
sync-2394 [005] 502.457091: ext4_sync_fs: (ffffffff81317650)
After putting back the skip stack to zero, we have:
sync-2270 [000] 748.052693: ext4_sync_fs: (ffffffff81317650)
sync-2270 [000] 748.052695: kernel_stack: <stack trace>
=> iterate_supers (ffffffff8126412e)
=> sys_sync (ffffffff8129c4b6)
=> entry_SYSCALL_64_fastpath (ffffffff8181f0b2)
sync-2270 [000] 748.053017: ext4_sync_fs: (ffffffff81317650)
sync-2270 [000] 748.053019: kernel_stack: <stack trace>
=> iterate_supers (ffffffff8126412e)
=> sys_sync (ffffffff8129c4b6)
=> entry_SYSCALL_64_fastpath (ffffffff8181f0b2)
sync-2270 [000] 748.053381: ext4_sync_fs: (ffffffff81317650)
sync-2270 [000] 748.053383: kernel_stack: <stack trace>
=> iterate_supers (ffffffff8126412e)
=> sys_sync (ffffffff8129c4b6)
=> entry_SYSCALL_64_fastpath (ffffffff8181f0b2)
Cc: stable@vger.kernel.org # v4.4+
Fixes:
|
||
---|---|---|
.. | ||
blktrace.c | ||
bpf_trace.c | ||
ftrace.c | ||
Kconfig | ||
Makefile | ||
power-traces.c | ||
ring_buffer_benchmark.c | ||
ring_buffer.c | ||
rpm-traces.c | ||
trace_benchmark.c | ||
trace_benchmark.h | ||
trace_branch.c | ||
trace_clock.c | ||
trace_entries.h | ||
trace_event_perf.c | ||
trace_events_filter_test.h | ||
trace_events_filter.c | ||
trace_events_trigger.c | ||
trace_events.c | ||
trace_export.c | ||
trace_functions_graph.c | ||
trace_functions.c | ||
trace_irqsoff.c | ||
trace_kdb.c | ||
trace_kprobe.c | ||
trace_mmiotrace.c | ||
trace_nop.c | ||
trace_output.c | ||
trace_output.h | ||
trace_printk.c | ||
trace_probe.c | ||
trace_probe.h | ||
trace_sched_switch.c | ||
trace_sched_wakeup.c | ||
trace_selftest_dynamic.c | ||
trace_selftest.c | ||
trace_seq.c | ||
trace_stack.c | ||
trace_stat.c | ||
trace_stat.h | ||
trace_syscalls.c | ||
trace_uprobe.c | ||
trace.c | ||
trace.h |