Hi Scott I understand what you said. I will use the function 'is_vm_hugetlb_page()' to hide the bit combinations according to your comments in the next version of patch set. But for the situation like below, there isn't an obvious structure 'vma', using 'is_vm_hugetlb_page()' maybe costly or even not possible. void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start, unsigned long end, unsigned long vmflag) { ... if (end == TLB_FLUSH_ALL || tlb_flushall_shift == -1 || vmflag & VM_HUGETLB) { local_flush_tlb(); goto flush_all; } ... } Thank you Wenwei 2015-07-07 5:34 GMT+08:00 Scott Wood <scottwood@xxxxxxxxxxxxx>: > On Fri, 2015-07-03 at 16:47 +0800, wenwei tao wrote: >> Hi Scott >> >> Thank you for your comments. >> >> Kernel already has that function: is_vm_hugetlb_page() , but the >> original code didn't use it, >> in order to keep the coding style of the original code, I didn't use it >> either. >> >> For the sentence like: "vma->vm_flags & VM_HUGETLB" , hiding it behind >> 'is_vm_hugetlb_page()' is ok, >> but the sentence like: "vma->vm_flags & >> (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)" appears in the patch 2/6, >> is it better to hide the bit combinations behind the >> is_vm_hugetlb_page() ? In my patch I just replaced it with >> "vma->vm_flags & (VM_LOCKED|VM_PFNMAP) || (vma->vm_flags & >> (VM_HUGETLB|VM_MERGEABLE)) == VM_HUGETLB". > > If you're going to do non-obvious things with the flags, it should be done in > one place rather than throughout the code. Why would you do the above and > not "vma->vm_flags & (VM_LOCKED | VM_PFNMAP) || is_vm_hugetlb_page(vma)"? > > -Scott > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>