Re: [PATCH v2 3/3] dax: use common 4k zero page for dax mmap reads

2017-06-16 Thread Ross Zwisler
On Thu, Jun 15, 2017 at 04:58:56PM +0200, Jan Kara wrote: > On Wed 14-06-17 11:22:11, Ross Zwisler wrote: > > @@ -216,17 +217,6 @@ static void dax_unlock_mapping_entry(struct > > address_space *mapping, > > dax_wake_mapping_entry_waiter(mapping, index, entry, false); > > } > > > > -static v

Re: [PATCH v2 3/3] dax: use common 4k zero page for dax mmap reads

2017-06-15 Thread Jan Kara
On Wed 14-06-17 11:22:11, Ross Zwisler wrote: > When servicing mmap() reads from file holes the current DAX code allocates > a page cache page of all zeroes and places the struct page pointer in the > mapping->page_tree radix tree. This has two major drawbacks: > > 1) It consumes memory unnecessa

[PATCH v2 3/3] dax: use common 4k zero page for dax mmap reads

2017-06-14 Thread Ross Zwisler
When servicing mmap() reads from file holes the current DAX code allocates a page cache page of all zeroes and places the struct page pointer in the mapping->page_tree radix tree. This has two major drawbacks: 1) It consumes memory unnecessarily. For every 4k page that is read via a DAX mmap() o