From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 20 Jan 2004 12:09:33 -0800 From: William Lee Irwin III Subject: Re: Anomaly in Buddy bitmaps? Message-ID: <20040120200933.GR32157@holomorphy.com> References: <20040120195729.90088.qmail@web9706.mail.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040120195729.90088.qmail@web9706.mail.yahoo.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Alok Mooley Cc: linux-mm@kvack.org List-ID: On Tue, Jan 20, 2004 at 11:57:29AM -0800, Alok Mooley wrote: > I wrote a module in kernel 2.6.0 for scanning a higher > order block from zone_mem_map for ZONE_NORMAL & > checking the buddy bitmaps for the same. > In the case of order 4, while scanning on the > order 4 block boundaries, I found an order 4 block > with page state 0000000001111111,where 0s represent > free pages & 1s represent order 0 allocations. The bit > in the order 3 bitmap corresponding to this 4th order > block was found to be a 0,whereas this bit should have > been a 1 as one 3rd order buddy is completely free. > I got the same result (a 0, where a 1 should have been > found) in another case too. > Is this an anomaly in the buddy bitmaps? Can the buddy > bitmaps ever be inconsistent? This could be the result of one of the free buddies being on the per-cpu freelists. Count those as "semi-free"; they count as allocated as far as the buddy bitmap is concerned. -- 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