Panic while using userstacktrace.
Issue
- When enable mm_kernel_pagefault trace event with userstacktrace option enabled, we got panic.
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The cause should be, userstacktrace itself can pagefault, so it can lead to dead-loop.
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Step to Reproduce:
- mount -t debugfs xxx /sys/kernel/debug
- echo userstacktrace > /sys/kernel/debug/tracing/trace_options
- echo 1 > /sys/kernel/debug/tracing/events/enable (or: echo 1 > /sys/kernel/debug/tracing/events/kmem/mm_kernel_pagefault/enable)
- We got panic immediately.
Environment
- Red Hat Enterprise Linux 6.0
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