From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751610AbbI2XHb (ORCPT ); Tue, 29 Sep 2015 19:07:31 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40207 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750985AbbI2XH3 (ORCPT ); Tue, 29 Sep 2015 19:07:29 -0400 Date: Tue, 29 Sep 2015 16:07:27 -0700 From: Andrew Morton To: Alexandru Moise <00moses.alexander00@gmail.com> Cc: vdavydov@parallels.com, mhocko@suse.cz, hannes@cmpxchg.org, tj@kernel.org, vbabka@suse.cz, mgorman@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] mm: fix declarations of nr, delta and nr_pagecache_reclaimable Message-Id: <20150929160727.ef70acf2e44575e9470a4025@linux-foundation.org> In-Reply-To: <20150927210425.GA20155@gmail.com> References: <20150927210425.GA20155@gmail.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-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 Sun, 27 Sep 2015 21:04:25 +0000 Alexandru Moise <00moses.alexander00@gmail.com> wrote: > The nr variable is meant to be returned by a function which is > declared as returning "unsigned long", so declare nr as such. > > Lower down we should also declare delta and nr_pagecache_reclaimable > as being unsigned longs because they're used to store the values > returned by zone_page_state() and zone_unmapped_file_pages() which > also happen to return unsigned integers. I rewrote the changelog rather a lot: Subject: mm/vmscan.c: fix types of some locals In zone_reclaimable_pages(), `nr' is returned by a function which is declared as returning "unsigned long", so declare it such. Negative values are meaningless here. In zone_pagecache_reclaimable() we should also declare `delta' and `nr_pagecache_reclaimable' as being unsigned longs because they're used to store the values returned by zone_page_state() and zone_unmapped_file_pages() which also happen to return unsigned integers. > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -194,7 +194,7 @@ static bool sane_reclaim(struct scan_control *sc) > > static unsigned long zone_reclaimable_pages(struct zone *zone) > { > - int nr; > + unsigned long nr; > > nr = zone_page_state(zone, NR_ACTIVE_FILE) + > zone_page_state(zone, NR_INACTIVE_FILE); OK. > @@ -3698,8 +3698,8 @@ static inline unsigned long zone_unmapped_file_pages(struct zone *zone) > /* Work out how many page cache pages we can reclaim in this reclaim_mode */ > static long zone_pagecache_reclaimable(struct zone *zone) > { > - long nr_pagecache_reclaimable; > - long delta = 0; > + unsigned long nr_pagecache_reclaimable; > + unsigned long delta = 0; > > /* > * If RECLAIM_UNMAP is set, then all file pages are considered Also OK, because zone_pagecache_reclaimable() takes care to avoid returning any negative values. In fact I believe we should also do this: --- a/mm/vmscan.c~mm-fix-declarations-of-nr-delta-and-nr_pagecache_reclaimable-fix +++ a/mm/vmscan.c @@ -3693,7 +3693,7 @@ static inline unsigned long zone_unmappe } /* Work out how many page cache pages we can reclaim in this reclaim_mode */ -static long zone_pagecache_reclaimable(struct zone *zone) +static unsigned long zone_pagecache_reclaimable(struct zone *zone) { unsigned long nr_pagecache_reclaimable; unsigned long delta = 0; _