On Thu, 2016-08-04 at 13:38 +0000, Ilya Lesokhin wrote: > You are right I just realized that this patch causes a memory leak, so sorry > for the spam. > > I just had problem understanding when compound pages are needed and when It > is enough to use an high order pages. > I thought that that high order pages are enough for this use case, tested it > and saw no problems. > > Unfortunately it seems you must use compound pages to keep track of the page > order. > put_page assumes that the order of a non-compound page is always 0. > It would be nice to document it somewhere but I'm not sure where.
Please do not top-post on netdev mailing list. ( Documentation/development-process/2.Process : line 422 ) AFAIK, only when we can call free_pages(p, order) and provide @order, we can avoid using __GFP_COMP at alloc time. But if some path has to use put_page(), then we are forced to use __GFP_COMP for high order pages. Thanks.
