From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751728AbeB0CAC (ORCPT ); Mon, 26 Feb 2018 21:00:02 -0500 Received: from mga14.intel.com ([192.55.52.115]:29726 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751634AbeB0CAB (ORCPT ); Mon, 26 Feb 2018 21:00:01 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,398,1515484800"; d="scan'208";a="178307447" Date: Tue, 27 Feb 2018 10:00:58 +0800 From: Aaron Lu To: David Rientjes Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Huang Ying , Dave Hansen , Kemi Wang , Tim Chen , Andi Kleen , Michal Hocko , Vlastimil Babka , Mel Gorman , Matthew Wilcox Subject: Re: [PATCH v3 2/3] mm/free_pcppages_bulk: do not hold lock when picking pages to free Message-ID: <20180227020058.GB9141@intel.com> References: <20180226135346.7208-1-aaron.lu@intel.com> <20180226135346.7208-3-aaron.lu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 26, 2018 at 01:53:10PM -0800, David Rientjes wrote: > On Mon, 26 Feb 2018, Aaron Lu wrote: > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 3154859cccd6..35576da0a6c9 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1116,13 +1116,11 @@ static void free_pcppages_bulk(struct zone *zone, int count, > > int migratetype = 0; > > int batch_free = 0; > > bool isolated_pageblocks; > > + struct page *page, *tmp; > > + LIST_HEAD(head); > > > > pcp->count -= count; > > - spin_lock(&zone->lock); > > - isolated_pageblocks = has_isolate_pageblock(zone); > > - > > while (count) { > > - struct page *page; > > struct list_head *list; > > > > /* > > @@ -1144,26 +1142,31 @@ static void free_pcppages_bulk(struct zone *zone, int count, > > batch_free = count; > > > > do { > > - int mt; /* migratetype of the to-be-freed page */ > > - > > page = list_last_entry(list, struct page, lru); > > /* must delete as __free_one_page list manipulates */ > > Looks good in general, but I'm not sure how I reconcile this comment with > the new implementation that later links page->lru again. Thanks for pointing this out. I think the comment is useless now since there is a list_add_tail right below so it's obvious we need to take the page off its original list. I'll remove the comment in an update. > > > list_del(&page->lru); > > > > - mt = get_pcppage_migratetype(page); > > - /* MIGRATE_ISOLATE page should not go to pcplists */ > > - VM_BUG_ON_PAGE(is_migrate_isolate(mt), page); > > - /* Pageblock could have been isolated meanwhile */ > > - if (unlikely(isolated_pageblocks)) > > - mt = get_pageblock_migratetype(page); > > - > > if (bulkfree_pcp_prepare(page)) > > continue; > > > > - __free_one_page(page, page_to_pfn(page), zone, 0, mt); > > - trace_mm_page_pcpu_drain(page, 0, mt); > > + list_add_tail(&page->lru, &head); > > } while (--count && --batch_free && !list_empty(list)); > > }