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SubjectRe: [Bug 10489] Kprobe smoke test lockdep warning
Thank you for reporting.

Actually, kprobes tries to fixup thread's flags in post_kprobe_handler
(which is called from kprobe_exceptions_notify) by
trace_hardirqs_fixup_flags(pt_regs->flags). However, even the irq flag
is set in pt_regs->flags, true hardirq is still off until returning
from do_debug. Thus, lockdep assumes that hardirq is off without annotation.

IMHO, one possible solution is that fixing hardirq flags right after
notify_die in do_debug instead of in post_kprobe_handler.


Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division


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