From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3604 invoked by alias); 23 Nov 2005 21:51:33 -0000 Received: (qmail 3597 invoked by uid 22791); 23 Nov 2005 21:51:33 -0000 X-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from gateway.sf.frob.com (HELO gateway.sf.frob.com) (64.81.54.130) by sourceware.org (qpsmtpd/0.31) with ESMTP; Wed, 23 Nov 2005 21:51:32 +0000 Received: from magilla.sf.frob.com (magilla.sf.frob.com [198.49.250.228]) by gateway.sf.frob.com (Postfix) with ESMTP id EE883357B; Wed, 23 Nov 2005 13:51:28 -0800 (PST) Received: by magilla.sf.frob.com (Postfix, from userid 5281) id A882F1809B9; Wed, 23 Nov 2005 13:51:28 -0800 (PST) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: fche@redhat.com (Frank Ch. Eigler) Cc: systemtap@sources.redhat.com Subject: Re: double fault -> PAGE_KERNEL flagged memory In-Reply-To: Frank Ch. Eigler's message of , 23 November 2005 15:59:51 -0500 Emacs: more boundary conditions than the Middle East. Message-Id: <20051123215128.A882F1809B9@magilla.sf.frob.com> Date: Wed, 23 Nov 2005 21:51:00 -0000 X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2005-q4/txt/msg00257.txt.bz2 > Then this is analogous to the problem of calling printk from within an > inconveniently placed kprobe. What can we do to eliminate this > vulnerability? Can we somehow arrange to "fault in" all probe-related > kernel-space vmalloc areas into new process' address spaces, so we don't > encounter this unintentional and undesirable reentrancy? What's the reason for using vmalloc then? Why not use kmalloc that doesn't need page table changes?