Re: [PATCH 3/3] mm/mmap.c: extract __vma_unlink_list as counter part for __vma_link_list

[Matthew Wilcox]

On Wed, Aug 21, 2019 at 08:52:34AM +0800, Wei Yang wrote:
> On Tue, Aug 20, 2019 at 10:26:29AM -0700, Matthew Wilcox wrote:
> >On Wed, Aug 14, 2019 at 11:19:37AM +0200, Vlastimil Babka wrote:
> >> On 8/14/19 8:57 AM, Wei Yang wrote:
> >> > On Tue, Aug 13, 2019 at 10:16:11PM -0700, Christoph Hellwig wrote:
> >> >>Btw, is there any good reason we don't use a list_head for vma linkage?
> >> > 
> >> > Not sure, maybe there is some historical reason?
> >> 
> >> Seems it was single-linked until 2010 commit 297c5eee3724 ("mm: make the vma
> >> list be doubly linked") and I guess it was just simpler to add the vm_prev link.
> >> 
> >> Conversion to list_head might be an interesting project for some "advanced
> >> beginner" in the kernel :)
> >
> >I'm working to get rid of vm_prev and vm_next, so it would probably be
> >wasted effort.
> 
> You mean replace it with list_head?

No, replace the rbtree with a new tree.  https://lwn.net/Articles/787629/