From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757962AbYFJVEh (ORCPT ); Tue, 10 Jun 2008 17:04:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754144AbYFJVEa (ORCPT ); Tue, 10 Jun 2008 17:04:30 -0400 Received: from mx1.redhat.com ([66.187.233.31]:60836 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753749AbYFJVE3 (ORCPT ); Tue, 10 Jun 2008 17:04:29 -0400 Date: Tue, 10 Jun 2008 17:03:48 -0400 From: Rik van Riel To: Andrew Morton Cc: linux-kernel@vger.kernel.org, lee.schermerhorn@hp.com, kosaki.motohiro@jp.fujitsu.com Subject: Re: [PATCH -mm 16/25] SHM_LOCKED pages are non-reclaimable Message-ID: <20080610170348.5750491c@cuia.bos.redhat.com> In-Reply-To: <20080606180514.93f620ff.akpm@linux-foundation.org> References: <20080606202838.390050172@redhat.com> <20080606202859.466929557@redhat.com> <20080606180514.93f620ff.akpm@linux-foundation.org> Organization: Red Hat, Inc X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.5; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 6 Jun 2008 18:05:14 -0700 Andrew Morton wrote: > > While working with Nick Piggin's mlock patches, > > Change log refers to information which its reader has not got a hope > of actually locating. Fixed that, and renamed everything to "unevictable". > > Use the AS_NORECLAIM flag to mark address_space of SHM_LOCKed > > shared memory regions as non-reclaimable. Then these pages > > will be culled off the normal LRU lists during vmscan. > > So I guess there's more justification for handling these pages in this > manner, because someone could come along later and unlock them. But > that isn't true of /dev/ram0 pages and ramfs pages, etc. Bingo. Ramdisk and ramfs pages will never become evictable again, while the pages in an SHM_LOCKED segment might. > > +static void check_move_noreclaim_page(struct page *page, struct zone *zone) > > +{ > > + > > + ClearPageNoreclaim(page); /* for page_reclaimable() */ > > Confused. Didn't we just lose track of our NR_NORECLAIM accounting? > > > + if (page_reclaimable(page, NULL)) { > > + enum lru_list l = LRU_INACTIVE_ANON + page_file_cache(page); > > + __dec_zone_state(zone, NR_NORECLAIM); No, we decrement the zone count here if the page is indeed unevictable. > > + list_move(&page->lru, &zone->list[l]); > > + __inc_zone_state(zone, NR_INACTIVE_ANON + l); > > + } else { > > + /* > > + * rotate noreclaim list > > + */ > > + SetPageNoreclaim(page); > > + list_move(&page->lru, &zone->list[LRU_NORECLAIM]); > > + } > > +} Or mark it unevictable again if it still is. > > + * scan_mapping_noreclaim_pages - scan an address space for reclaimable pages > > + * @mapping: struct address_space to scan for reclaimable pages > > + * > > + * Scan all pages in mapping. Check non-reclaimable pages for > > + * reclaimability and move them to the appropriate zone lru list. > > + */ > > +void scan_mapping_noreclaim_pages(struct address_space *mapping) > > +{ > This function can spend fantastically large amounts of time under > spin_lock_irq(). I'll leave it up to Lee and Kosaki-san to fix this, once you have the cleaned up versions. Fixing this now would just delay my other janitorial work on this patch series... -- All Rights Reversed