From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1Axy9e-0007BK-BL for user-mode-linux-devel@lists.sourceforge.net; Mon, 01 Mar 2004 16:53:02 -0800 Received: from [12.177.129.25] (helo=ccure.user-mode-linux.org) by sc8-sf-mx1.sourceforge.net with esmtp (TLSv1:DES-CBC3-SHA:168) (Exim 4.30) id 1Axxxc-0006R9-Hj for user-mode-linux-devel@lists.sourceforge.net; Mon, 01 Mar 2004 16:40:36 -0800 Message-Id: <200403020111.i221BAM9025673@ccure.user-mode-linux.org> Subject: Re: [uml-devel] [PATCH] fix writing into /dev/kmem In-Reply-To: Your message of "Sun, 29 Feb 2004 17:20:19 +0100." <200402291720.19359.blaisorblade_spam@yahoo.it> References: <20040229023636.GB8272@ccure.user-mode-linux.org> <200402291720.19359.blaisorblade_spam@yahoo.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii From: Jeff Dike Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Mon, 01 Mar 2004 20:11:10 -0500 To: BlaisorBlade Cc: user-mode-linux-devel@lists.sourceforge.net blaisorblade_spam@yahoo.it said: > the i386 Oopses, normally, kill only the thread which triggered the > fault - while instead Uml panics altogether. Cannot this be changed > at arch/um/kernel/trap_kern.c:segv()? If there's an unexplained kernel mode access fault, anything could be wrong. I don't see that it's reasonable to just kill the process when kernel data could be corrupted as far as we know. I don't know why x86 thinks it can just kill the process. > By the way: in handle_page_fault(), there is some dead code (attached > is the removal patch). That shouldn't be dead code. I think it should be attached to the VM_FAULT_OOM case - I copied it from x86, so check there to be sure. > I also do not understand the loop around handle_mm_fault call, but I > could be wrong: are you sure that after a successful handle_mm_fault > (i.e. a major or minor fault) pte_present(*pte) could be false? If > handle_mm_fault is not successful, we exit the loop anyway. It's possible that the page could have been swapped out between fixing the fault and the return from handle_mm_fault. Way back in history, I had a check for the same fault happening twice in a row, and panicing if it happened. This was when UML's fault handling still needed debugging. To prevent the case I just mentioned from triggering that panic, I added the loop to make sure the page was good before returning to userspace. Jeff ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel