From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 27 Jun 2001 11:41:55 +0200 From: Andrea Arcangeli Subject: Re: patch: highmem zero-bounce Message-ID: <20010627114155.A31910@athlon.random> References: <20010626182215.C14460@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20010626182215.C14460@suse.de>; from axboe@suse.de on Tue, Jun 26, 2001 at 06:22:15PM +0200 Sender: owner-linux-mm@kvack.org Return-Path: To: Jens Axboe Cc: Linux Kernel , linux-mm@kvack.org, "ZINKEVICIUS,MATT (HP-Loveland,ex1)" List-ID: On Tue, Jun 26, 2001 at 06:22:15PM +0200, Jens Axboe wrote: > Hi, > > I updated the patches to 2.4.6-pre5, and removed the zone-dma32 > addition. This means that machines with > 4GB of RAM will need to go all good, we can relax the ZONE_NORMAL later, that's a separate problem with skipping the bounces. I can see one mm corruption race condition in the patch, you missed nested irq in the for kmap_irq_bh (PIO). You must _always_ __cli/__save_flags before accessing the KMAP_IRQ_BH slot, in case the remapping is required (so _only_ when the page is in the highmem zone). Otherwise memory corruption will happen when the race triggers (for example two ide disks in PIO mode doing I/O at the same time connected to different irq sources). Andrea -- 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/