[Bug testsuite/10212] System hangs on running check.exp in systemtap snapshot : 0.9.7/0.141 commit release-0.9.7-167-geee30f4

["fche at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

------- Additional Comments From fche at redhat dot com  2009-06-06 14:21 -------
I see signs of two different problems in the kernel bug list.

First, the arch_arm_kprobe->"BUG: using smp_processor_id() in preemptible"
path, it seems like a kernel kprobe-implementation bug, in that it calls
get_kprobe_ctlblk() without an active disable_preempt().  Systemtap could
conceivably work around this by wrapping our kprobe registration calls
in a preempt_disable/enable.


Second, the stp_strncpy_from_user->__might_sleep path, this could be
a runtime bug, or perhaps the absence of a suitable s390x facility to
atomically copy data out.  In fact, runtime/copy.c says:

#elif defined (__s390__) || defined (__s390x__)
#define __stp_strncpy_from_user(dst,src,count,res) \
        do { res = strncpy_from_user(dst, src, count); } while(0)

#endif

which includes a might_sleep().  So it seems the s390x kernel needs
some more code.


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http://sourceware.org/bugzilla/show_bug.cgi?id=10212

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