1ERROR::FAULT(7stap)                                        ERROR::FAULT(7stap)
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NAME

6       error::fault - memory access faults
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DESCRIPTION

12       Read  or  write  faults  can  occur during the operation of a systemtap
13       script, if the script causes dereferencing of a pointer that turns  out
14       to  be  invalid.  This can be caused by using context variables that do
15       not happen to have valid values, or perhaps references to  memory  that
16       is unavailable at that moment due to paging.
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18       These  fault  conditions are benign because they are caught by the sys‐
19       temtap runtime, which cleanly terminates the script.  If quick termina‐
20       tion  is  not  desired,  consider  using  the  --skip-badvars or --sup‐
21       press-handler-errors or -DMAXERRORS=NN stap options, or wrapping  rele‐
22       vant parts of the probe handlers in a try/catch block.
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24       It may be possible to adjust the target program, to make it more likely
25       that needed context variables are paged in  when  systemtap  looks  for
26       them.   Consider  adding  some  lightweight processing on the key vari‐
27       ables, like a strlen(foo) for a string, or iterating across elements of
28       an  array  or  linked list, or touching a few bytes of a heap-allocated
29       block.  The idea is to trigger any page faults in the  target  program,
30       before systemtap would need to (but can't).
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SEE ALSO

33       stap(1),
34       error::reporting(7stap)
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38                                                           ERROR::FAULT(7stap)