On Wed, Jul 31, 2013 at 2:37 PM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote: > On Wed, Jul 31, 2013 at 02:21:38PM +0800, Hillf Danton wrote: >> On Wed, Jul 31, 2013 at 12:41 PM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote: >> > On Wed, Jul 31, 2013 at 10:49:24AM +0800, Hillf Danton wrote: >> >> On Wed, Jul 31, 2013 at 10:27 AM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote: >> >> > On Mon, Jul 29, 2013 at 03:24:46PM +0800, Hillf Danton wrote: >> >> >> On Mon, Jul 29, 2013 at 1:31 PM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote: >> >> >> > alloc_huge_page_node() use dequeue_huge_page_node() without >> >> >> > any validation check, so it can steal reserved page unconditionally. >> >> >> >> >> >> Well, why is it illegal to use reserved page here? >> >> > >> >> > If we use reserved page here, other processes which are promised to use >> >> > enough hugepages cannot get enough hugepages and can die. This is >> >> > unexpected result to them. >> >> > >> >> But, how do you determine that a huge page is requested by a process >> >> that is not allowed to use reserved pages? >> > >> > Reserved page is just one for each address or file offset. If we need to >> > move this page, this means that it already use it's own reserved page, this >> > page is it. So we should not use other reserved page for moving this page. >> > >> Hm, how do you determine "this page" is not buddy? > > If this page comes from the buddy, it doesn't matter. It imply that > this mapping cannot use reserved page pool, because we always allocate > a page from reserved page pool first. > A buddy page also implies, if the mapping can use reserved pages, that no reserved page was available when requested. Now we can try reserved page again. -- 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>