Any chance that a device connected via serial (or an USB device which uses USB/Serial conversion)
triggers them? My cheap pl2303 device seems to send spurious BREAKs every once in a while, which
results in the described behavior, as the kernel will print the help line for any character which
is not a valid sysrq. (The probability to trigger another sysrq with random data is much lower, but
did you find any other printout of an sysrq in your logs?)
Best regards,
Arnd Hannemann
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