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static int copy_mm(unsigned long clone_flags, struct task_struct *tsk){ struct mm_struct *mm, *oldmm; int retval;  tsk->min_flt = tsk->maj_flt = 0; tsk->nvcsw = tsk->nivcsw = 0;#ifdef CONFIG_DETECT_HUNG_TASK tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;#endif  tsk->mm = NULL; tsk->active_mm = NULL;  /*  * Are we cloning a kernel thread?  *  * We need to steal a active VM for that..  */ oldmm = current->mm; if (!oldmm)  return 0;  /* initialize the new vmacache entries */ vmacache_flush(tsk);  if (clone_flags & CLONE_VM) {  atomic_inc(&oldmm->mm_users);  mm = oldmm;  goto good_mm; }  retval = -ENOMEM; mm = dup_mm(tsk); if (!mm)  goto fail_nomem; good_mm: tsk->mm = mm; tsk->active_mm = mm; return 0; fail_nomem: return retval;} /* * Allocate a new mm structure and copy contents from the * mm structure of the passed in task structure. */static struct mm_struct *dup_mm(struct task_struct *tsk){ struct mm_struct *mm, *oldmm = current->mm; int err;  mm = allocate_mm(); if (!mm)  goto fail_nomem;  memcpy(mm, oldmm, sizeof(*mm));  if (!mm_init(mm, tsk))  goto fail_nomem;  err = dup_mmap(mm, oldmm); if (err)  goto free_pt;  mm->hiwater_rss = get_mm_rss(mm); mm->hiwater_vm = mm->total_vm;  if (mm->binfmt && !try_module_get(mm->binfmt->module))  goto free_pt;  return mm; free_pt: /* don't put binfmt in mmput, we haven't got module yet */ mm->binfmt = NULL; mmput(mm); fail_nomem: return NULL;}  

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