From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id 6B88F6B004A for ; Tue, 19 Jul 2011 23:53:43 -0400 (EDT) Date: Wed, 20 Jul 2011 13:53:32 +1000 From: Dave Chinner Subject: Re: vmscan: shrinker->nr updates race and go wrong Message-ID: <20110720035332.GC24009@devil.redhat.com> References: <20110719200826.GC6445@shale.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110719200826.GC6445@shale.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Dan Carpenter Cc: "open list:MEMORY MANAGEMENT" On Tue, Jul 19, 2011 at 11:08:26PM +0300, Dan Carpenter wrote: > Hi Dave, > > There is a sign error in e5b94d7463e0 "vmscan: shrinker->nr updates > race and go wrong" > > mm/vmscan.c +274 shrink_slab(41) > warn: unsigned 'total_scan' is never less than zero. > > 268 total_scan = nr; > 269 max_pass = do_shrinker_shrink(shrinker, shrink, 0); > 270 delta = (4 * nr_pages_scanned) / shrinker->seeks; > 271 delta *= max_pass; > 272 do_div(delta, lru_pages + 1); > 273 total_scan += delta; > 274 if (total_scan < 0) { > ^^^^^^^^^^^^^^ > total_scan is unsigned so it's never less than zero here. Obviously. You'd think a kernel build would warn about that given that it's almost always a bug, wouldn't you? I'll send a patch to fix it up.... Cheers, Dave. -- Dave Chinner dchinner@redhat.com -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org