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From: "me at serhei dot io" <sourceware-bugzilla@sourceware.org>
To: systemtap@sourceware.org
Subject: [Bug kprobes/26755] New: recent rawhide: grabbing several
 lock:lock_* tracepoints leads to hard lockup?
Date: Mon, 19 Oct 2020 19:54:46 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D26755

            Bug ID: 26755
           Summary: recent rawhide: grabbing several lock:lock_*
                    tracepoints leads to hard lockup?
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: kprobes
          Assignee: systemtap at sourceware dot org
          Reporter: me at serhei dot io
  Target Milestone: ---

Started seeing this on the rawhide buildbot with kprobes_onthefly.exp (which
probes all possible tracepoints in the 'hardcore' case). On a lockdep enabl=
ed
kernel this grabs lock:lock_{acquire,acquired,release,contended}.

The tricky part is that the hard lockup only happens if more than one of th=
ese
tracepoints is probed.

For now I'm disabling those tracepoints in the testcase (similar to hcall_*
blacklist on ppc) but we need to figure out if something/anything needs to =
be
blacklisted for recent kernels.

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