STINNER Victor <vstin...@redhat.com> added the comment:
"""
...
_PyObject_FastCallDict(callable = (nil), args = 0x2008bf70, nargs = 540036208,
kwargs = 0x0000014d), line 100 in "call.c"
object_vacall(callable = 0x100de658, vargs = warning: Unable to access address
0xdbdbdbdb from core
(invalid char ptr (0xdbdbdbdb))), line 1200 in "call.c"
_PyObject_CallMethodIdObjArgs(obj = 0x30061db0, name = 0x20039710, ... =
0x304e9fa8, 0x3003a7a0, 0x0, 0x4deb7, 0xcb, 0x306aee88), line 1250 in "call.c"
import_find_and_load(abs_name = 0x3097abf8), line 1652 in "import.c"
...
"""
Extract of _PyObject_CallMethodIdObjArgs:
PyObject *
_PyObject_CallMethodIdObjArgs(PyObject *obj,
struct _Py_Identifier *name, ...)
{
va_list vargs;
PyObject *callable, *result;
if (obj == NULL || name == NULL) {
return null_error();
}
callable = _PyObject_GetAttrId(obj, name);
if (callable == NULL) {
return NULL;
}
va_start(vargs, name);
result = object_vacall(callable, vargs);
va_end(vargs);
Py_DECREF(callable);
return result;
}
I don't know how va_list and va_start are implemented in XLC, but 0xDBDBDBDB
looks like the byte pattern for released memory in Python: you can now use
_PyMem_IsPtrFreed() function from pycore_pymem.h to check if a pointer looks
like "freed":
static inline int _PyMem_IsPtrFreed(void *ptr)
{
uintptr_t value = (uintptr_t)ptr;
#if SIZEOF_VOID_P == 8
return (value == (uintptr_t)0xCDCDCDCDCDCDCDCD
|| value == (uintptr_t)0xDDDDDDDDDDDDDDDD
|| value == (uintptr_t)0xFDFDFDFDFDFDFDFD);
#elif SIZEOF_VOID_P == 4
return (value == (uintptr_t)0xCDCDCDCD
|| value == (uintptr_t)0xDDDDDDDD
|| value == (uintptr_t)0xFDFDFDFD);
#else
# error "unknown pointer size"
#endif
}
Maybe modify object_vacall() to add "assert(!_PyMem_IsPtrFreed(vargs));". You
may need #include "pycore_pymem.h".
Good luck with debug :-(
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<https://bugs.python.org/issue35828>
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