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Maintained by go/gitwatcher - Please do not modify manually. [ID: 762704]
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Description
#1As mentioned in bug 172213097 the buddy lockup detector does not provide meaningful debug information, i.e. stack dumps of the locked up core.
While a true hardlockup detector such as proposed in bug 172228850 would provide such information, not all platforms can support it. The platforms left out would still end up using the buddy lockup detector, or none at all.
Recently a series [1] that uses pseudo-NMIs on arm64 for IPIs allows getting NMI backtraces on hard locked up cores. This was tested on RK3399 on mainline [2] with:
Subsequently when an RCU stall is detected, an NMI backtrace is logged:
SysRq backtraces also work properly.
Without pseudo-NMIs enabled, only a task dump is logged:
And SysRq backtraces aren't available for all cores.
[1]https://lore.kernel.org/linux-arm-kernel/1604317487-14543-1-git-send-email-sumit.garg@linaro.org/ https://lore.kernel.org/linux-arm-kernel/CAGb2v66mVoWiCibjq25d3Z8OvbWNO9p+vMo761RJLiD-BqVbqw@mail.gmail.com/
[2]