process memory usage

vm_stat_account

void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
{
    mm->total_vm += npages;

    if (is_exec_mapping(flags))
        mm->exec_vm += npages;
    else if (is_stack_mapping(flags))
        mm->stack_vm += npages;
    else if (is_data_mapping(flags))
        mm->data_vm += npages;
}

Initially these pages are anonymous pages or file pages

239 /*
240  * Executable code area - executable, not writable, not stack
241  */
242 static inline bool is_exec_mapping(vm_flags_t flags)　－－－－　这里使用的是文件页
243 {
244     return (flags & (VM_EXEC | VM_WRITE | VM_STACK)) == VM_EXEC;
245 }
246
247 /*  
248  * Stack area - atomatically grows in one direction
249  *  
250  * VM_GROWSUP / VM_GROWSDOWN VMAs are always private anonymous:
251  * do_mmap() forbids all other combinations.
252  */
253 static inline bool is_stack_mapping(vm_flags_t flags)　－－－－　匿名页
254 {
255     return (flags & VM_STACK) == VM_STACK;
256 }
257
258 /*
259  * Data area - private, writable, not stack
260  */
261 static inline bool is_data_mapping(vm_flags_t flags)　　－－－－　匿名页
262 {
263     return (flags & (VM_WRITE | VM_SHARED | VM_STACK)) == VM_WRITE;
264 }