From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f172.google.com (mail-io0-f172.google.com [209.85.223.172]) by kanga.kvack.org (Postfix) with ESMTP id 3A0BE6B0253 for ; Tue, 22 Sep 2015 14:26:53 -0400 (EDT) Received: by iofb144 with SMTP id b144so23171141iof.1 for ; Tue, 22 Sep 2015 11:26:53 -0700 (PDT) Received: from mail-ig0-x232.google.com (mail-ig0-x232.google.com. [2607:f8b0:4001:c05::232]) by mx.google.com with ESMTPS id 72si3679406iot.191.2015.09.22.11.26.52 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 22 Sep 2015 11:26:52 -0700 (PDT) Received: by igcrk20 with SMTP id rk20so86354319igc.1 for ; Tue, 22 Sep 2015 11:26:52 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1442903021-3893-1-git-send-email-mingo@kernel.org> <1442903021-3893-6-git-send-email-mingo@kernel.org> Date: Tue, 22 Sep 2015 11:26:52 -0700 Message-ID: Subject: Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late() From: Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Andy Lutomirski Cc: Ingo Molnar , Linux Kernel Mailing List , linux-mm , Andrew Morton , Denys Vlasenko , Brian Gerst , Peter Zijlstra , Borislav Petkov , "H. Peter Anvin" , Oleg Nesterov , Waiman Long , Thomas Gleixner On Tue, Sep 22, 2015 at 11:00 AM, Andy Lutomirski wrote: > > I really really hate the vmalloc fault thing. It seems to work, > rather to my surprise. It doesn't *deserve* to work, because of > things like the percpu TSS accesses in the entry code that happen > without a valid stack. The thing is, I think you're misguided in your hatred. The reason I say that is because I think we should just embrace the fact that faults can and do happen in the kernel in very inconvenient places, and not just in code we "control". Even if you get rid of the vmalloc fault, you'll still have debug faults, and you'll still have NMI's and horrible crazy machine check faults. I actually think teh vmalloc fault is a good way to just let people know "pretty much anything can trap, deal with it". And I think trying to eliminate them is the wrong thing, because it forces us to be so damn synchronized. This whole patch-series is a prime example of why that is a bad bad things. We want to have _less_ synchronization. Linus -- 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/ . Don't email: email@kvack.org