Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755601AbYGDGeP (ORCPT ); Fri, 4 Jul 2008 02:34:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751826AbYGDGeA (ORCPT ); Fri, 4 Jul 2008 02:34:00 -0400 Received: from einhorn.in-berlin.de ([192.109.42.8]:54043 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751633AbYGDGd7 (ORCPT ); Fri, 4 Jul 2008 02:33:59 -0400 X-Envelope-From: stefanr@s5r6.in-berlin.de Message-ID: <486DC42A.2080105@s5r6.in-berlin.de> Date: Fri, 04 Jul 2008 08:33:14 +0200 From: Stefan Richter User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.13) Gecko/20080614 SeaMonkey/1.1.9 MIME-Version: 1.0 To: Hidehiro Kawai CC: Philippe De Muyter , Michael Kerrisk , Michael Kerrisk , linux-kernel@vger.kernel.org, libdc1394-devel@lists.sourceforge.net, sugita , Satoshi OSHIMA Subject: Re: mmap'ed memory in core files ? References: <20080701132149.GA32510@frolo.macqel> <517f3f820807011116g6ce1b3e1qf166070f7a4c523f@mail.gmail.com> <20080702105027.GA1111@frolo.macqel> <486C4CC5.2060006@hitachi.com> <20080703092247.GA13430@frolo.macqel> <486DBA21.3080106@hitachi.com> In-Reply-To: <486DBA21.3080106@hitachi.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2199 Lines: 56 Hidehiro Kawai wrote: > Philippe De Muyter wrote: >> drivers/ieee1394/dma.c: >> int dma_region_mmap(struct dma_region *dma, struct file *file, >> struct vm_area_struct *vma) >> { >> [...] >> vma->vm_ops = &dma_region_vm_ops; >> vma->vm_private_data = dma; >> vma->vm_file = file; >> vma->vm_flags |= VM_RESERVED; >> >> return 0; >> } >> >> So, actually the zone I would like to get dumped in the core file is tagged >> VM_RESERVED. >> >> I see the following ways to solve my problem : >> - do not tag the zone as VM_RESERVED in ieee1394::dma_region_mmap >> - tag the zone as VM_ALWAYSDUMP in ieee1394::dma_region_mmap >> - add a bit in coredump_filter to dump the VM_RESERVED zones. >> >> As I don't know the real meaning of VM_RESERVED, I do not know which choice >> is the best one for the official kernel tree, I don't know these things either. But among else, VM_RESERVED prevents a vma from being swapped out. Makes kind of sense, given that besides the CPUs also the FireWire controller writes to this memory. >> but locally I'll go for >> adding VM_ALWAYSDUMP in ieee1394::dma_region_mmap. > > I'm afraid I don't know real usages of VM_RESERVED and VM_IO, either. > Allowing everyone to choose whether dump the dma region or not, > perhaps we need to introduce a new VM flag (e.g. VM_DUMPABLE) and > a coredump_filter bit which controls (VM_IO | VM_RESERVED) && > VM_DUMPABLE area, for example. > > I think it is also OK to just add VM_ALWAYSDUMP flag to the dma > region if the device driver knows the region is safely readable > and small enough. It is safely readable. I don't know if it is small enough. The size of the DMA buffer is AFAIK chosen by userspace (by the application program or maybe a library) which uses the character device file ABIs for isochronous FireWire IO of raw1394, video1394, or dv1394. -- Stefan Richter -=====-==--- -=== --=-- http://arcgraph.de/sr/ -- 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/