Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764972AbZLQRKo (ORCPT ); Thu, 17 Dec 2009 12:10:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764962AbZLQRKc (ORCPT ); Thu, 17 Dec 2009 12:10:32 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:52892 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757585AbZLQRK3 (ORCPT ); Thu, 17 Dec 2009 12:10:29 -0500 Date: Thu, 17 Dec 2009 12:10:25 -0500 From: Christoph Hellwig To: tytso@mit.edu, Linus Torvalds , Kyle McMartin , linux-parisc@vger.kernel.org, Linux Kernel Mailing List , James.Bottomley@suse.de, hch@infradead.org, linux-arch@vger.kernel.org, Jens Axboe Subject: Re: [git patches] xfs and block fixes for virtually indexed arches Message-ID: <20091217171025.GB10431@infradead.org> References: <20091216043618.GB9104@hera.kernel.org> <20091217132256.GO28962@bombadil.infradead.org> <20091217163036.GE2123@thunk.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091217163036.GE2123@thunk.org> User-Agent: Mutt/1.5.19 (2009-01-05) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1333 Lines: 27 On Thu, Dec 17, 2009 at 11:30:36AM -0500, tytso@mit.edu wrote: > That's because apparently the iSCSI and DMA blocks assume that they > have Real Pages (tm) passed to block I/O requests, and apparently XFS > ran into problems when sending vmalloc'ed pages. I don't know if this > is a problem if we pass the bio layer addresses coming from the SLAB > allocator, but oral tradition seems to indicate this is problematic, > although no one has given me the full chapter and verse explanation > about why this is so. Actually at least iscsi now has a workaround for that by checking for PageSlab. Back when we deal with the XFS issue that check was only available with debug options enabled. I tried to sort it out by agreeing with the block and iscsi folks that either a) we need to send down refcountable pages b) block drivers need to accept kmalloced pages I could not get any afreement, and thus we stopped using the kmalloced pages in XFS which was easy enough. A bit later people fixed iscsi, but we still don't have formal rules about what is acceptable to the block layer. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/