wuqiang 2b7e6a0734 kprobes: kretprobe events missing on 2-core KVM guest ... [ Upstream commit 3b7ddab8a1 ] Default value of maxactive is set as num_possible_cpus() for nonpreemptable systems. For a 2-core system, only 2 kretprobe instances would be allocated in default, then these 2 instances for execve kretprobe are very likely to be used up with a pipelined command. Here's the testcase: a shell script was added to crontab, and the content of the script is: #!/bin/sh do_something_magic `tr -dc a-z < /dev/urandom | head -c 10` cron will trigger a series of program executions (4 times every hour). Then events loss would be noticed normally after 3-4 hours of testings. The issue is caused by a burst of series of execve requests. The best number of kretprobe instances could be different case by case, and should be user's duty to determine, but num_possible_cpus() as the default value is inadequate especially for systems with small number of cpus. This patch enables the logic for preemption as default, thus increases the minimum of maxactive to 10 for nonpreemptable systems. Link: https://lore.kernel.org/all/20221110081502.492289-1-wuqiang.matt@bytedance.com/ Signed-off-by: wuqiang <wuqiang.matt@bytedance.com> Reviewed-by: Solar Designer <solar@openwall.com> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2023-01-04 11:26:27 +01:00
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coresight	coresight: docs: Fix a broken reference	2022-10-21 12:38:39 +02:00
postprocess	…
rv	rv/monitor: Add the wwnr monitor	2022-07-30 14:01:30 -04:00
boottime-trace.rst	docs/trace: fix a label of boottime-trace	2021-12-10 13:58:53 -07:00
events-kmem.rst	…
events-msr.rst	…
events-nmi.rst	…
events-power.rst	…
events.rst	tracing: Add ustring operation to filtering string pointers	2022-01-14 03:42:24 -05:00
fprobe.rst	docs: fprobe: Add fprobe description to ftrace-use.rst	2022-03-17 20:17:08 -07:00
ftrace-design.rst	…
ftrace-uses.rst	…
ftrace.rst	tracing: Add documentation for trace clock tai	2022-04-27 17:19:30 -04:00
function-graph-fold.vim	…
histogram-design.rst	…
histogram.rst	tracing/histogram: Update document for KEYS_MAX size	2022-11-10 18:17:33 +01:00
hwlat_detector.rst	…
index.rst	Documentation/rv: Add a basic documentation	2022-07-30 14:01:29 -04:00
intel_th.rst	…
kprobes.rst	kprobes: kretprobe events missing on 2-core KVM guest	2023-01-04 11:26:27 +01:00
kprobetrace.rst	tracing: Auto generate event name when creating a group of events	2022-07-24 19:11:17 -04:00
mmiotrace.rst	…
osnoise-tracer.rst	docs: Remove duplicated words in trace/osnoise-tracer	2022-02-24 10:42:20 -07:00
ring-buffer-design.rst	…
stm.rst	…
sys-t.rst	…
timerlat-tracer.rst	tracing/timerlat: Print stacktrace in the IRQ handler if needed	2022-05-26 21:13:00 -04:00
tracepoint-analysis.rst	…
tracepoints.rst	…
uprobetracer.rst	tracing: Auto generate event name when creating a group of events	2022-07-24 19:11:17 -04:00
user_events.rst	tracing/user_events: Remove eBPF interfaces	2022-04-02 08:40:09 -04:00