From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 20 Aug 2004 22:37:35 -0700 From: William Lee Irwin III Subject: Re: [Lhms-devel] Re: [RFC] free_area[] bitmap elimination [0/3] Message-ID: <20040821053735.GV11200@holomorphy.com> References: <4126B3F9.90706@jp.fujitsu.com> <20040821025543.GS11200@holomorphy.com> <20040821.135624.74737461.taka@valinux.co.jp> <20040821052116.GU11200@holomorphy.com> <4126DFB4.7070404@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4126DFB4.7070404@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Hiroyuki KAMEZAWA Cc: Hirokazu Takahashi , linux-mm@kvack.org, lhms-devel@lists.sourceforge.net List-ID: William Lee Irwin III wrote: >> In __free_pages_bulk() changing BUG_ON(bad_range(zone, buddy1)) to >> if (bad_range(zone, buddy1)) break; should fix this. The start of >> the zone must be aligned to MAX_ORDER so buddy2 doesn't need checks. >> It may be worthwhile to make a distinction the bounds checks and the >> zone check and to BUG_ON() the zone check in isolation and not repeat >> the bounds check for the validity check. On Sat, Aug 21, 2004 at 02:37:56PM +0900, Hiroyuki KAMEZAWA wrote: > Okay, I understand several BUG_ON() are needless. > I'll be more carefull to recognize what is checked. It's not that it's needless, it's that beforehand the bitmap rounding up to an even number ensured the __test_and_change_bit() check would prevent the bounds check from ever failing, but after the bitmap is eliminated, the bounds check is needed to see if we're even examining a valid page structure for whether the page can be merged. -- wli -- 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: aart@kvack.org