From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 14 Apr 2006 11:31:04 -0700 From: Andrew Morton Subject: Re: Implement lookup_swap_cache for migration entries Message-Id: <20060414113104.72a5059b.akpm@osdl.org> In-Reply-To: References: <20060413235406.15398.42233.sendpatchset@schroedinger.engr.sgi.com> <20060413235416.15398.49978.sendpatchset@schroedinger.engr.sgi.com> <20060413171331.1752e21f.akpm@osdl.org> <20060413174232.57d02343.akpm@osdl.org> <20060413180159.0c01beb7.akpm@osdl.org> <20060413222921.2834d897.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: hugh@veritas.com, linux-kernel@vger.kernel.org, lee.schermerhorn@hp.com, linux-mm@kvack.org, taka@valinux.co.jp, marcelo.tosatti@cyclades.com, kamezawa.hiroyu@jp.fujitsu.com List-ID: Christoph Lameter wrote: > > This undoes the optimization that resulted in a yield in do_swap_cache(). > do_swap_cache() stays as is. Instead we convert the migration entry to > a page * in lookup_swap_cache. > > For the non swap case we need a special macro version of lookup_swap_cache > that is only capable of handling migration cache entries. > > ... > > @@ -305,6 +306,12 @@ struct page * lookup_swap_cache(swp_entr > { > struct page *page; > > + if (is_migration_entry(entry)) { > + page = migration_entry_to_page(entry); > + get_page(page); > + return page; > + } What locking ensures that the state of `entry' remains unaltered across the is_migration_entry() and migration_entry_to_page() calls? > > +/* > + * Must use a macro for lookup_swap_cache since the functions > + * used are only available in certain contexts. > + */ > +#define lookup_swap_cache(__swp) \ > +({ struct page *p = NULL; \ > + if (is_migration_entry(__swp)) { \ > + p = migration_entry_to_page(__swp); \ > + get_page(p); \ > + } \ > + p; \ > +}) hm. Can nommu do any of this? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org