From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 27 Oct 2004 09:01:24 -0700 From: "Martin J. Bligh" Subject: Re: news about IDE PIO HIGHMEM bug (was: Re: 2.6.9-mm1) Message-ID: <1246750000.1098892883@[10.10.2.4]> In-Reply-To: <1246230000.1098892359@[10.10.2.4]> References: <58cb370e041027074676750027@mail.gmail.com> <417FBB6D.90401@pobox.com> <1246230000.1098892359@[10.10.2.4]> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Jeff Garzik , Linux Kernel , linux-mm@kvack.org Cc: Bartlomiej Zolnierkiewicz , "Randy.Dunlap" , William Lee Irwin III , Jens Axboe List-ID: --"Martin J. Bligh" wrote (on Wednesday, October 27, 2004 08:52:39 -0700): >> Bartlomiej Zolnierkiewicz wrote: >>> We have stuct page of the first page and a offset. >>> We need to obtain struct page of the current page and map it. >> >> >> Opening this question to a wider audience. >> >> struct scatterlist gives us struct page*, and an offset+length pair. The struct page* is the _starting_ page of a potentially multi-page run of data. >> >> The question: how does one get struct page* for the second, and successive pages in a known-contiguous multi-page run, if one only knows the first page? > > If it's a higher order allocation, just page+1 should be safe. If it just > happens to be contig, it might cross a discontig boundary, and not obey > that rule. Very unlikely, but possible. To repeat what I said in IRC ... ;-) Actually, you could check this with the pfns being the same when >> MAX_ORDER-1. We should be aligned on a MAX_ORDER boundary, I think. However, pfn_to_page(page_to_pfn(page) + 1) might be safer. If rather slower. M. -- 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