Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752245AbcJITMC (ORCPT ); Sun, 9 Oct 2016 15:12:02 -0400 Received: from mail-oi0-f51.google.com ([209.85.218.51]:36096 "EHLO mail-oi0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbcJITMA (ORCPT ); Sun, 9 Oct 2016 15:12:00 -0400 MIME-Version: 1.0 In-Reply-To: References: <20161007222059.GS19539@ZenIV.linux.org.uk> From: Linus Torvalds Date: Sun, 9 Oct 2016 12:11:58 -0700 X-Google-Sender-Auth: EMjWrC_YKhkP-cGbWHyxcYBwuQk Message-ID: Subject: Re: [git pull] vfs pile 1 (splice) To: Al Viro , Andrew Morton , Jens Axboe , "Ted Ts'o" , Christoph Lameter Cc: Linux Kernel Mailing List , linux-fsdevel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1316 Lines: 31 On Sun, Oct 9, 2016 at 11:40 AM, Linus Torvalds wrote: > > I'll continue with *just* SLUB debugging on, but I thought it was > interesting how enabling more memory access debugging actually ends up > changing some really subtle code. Indeed, now with DEBUG_PAGEALLOC disabled, I got a crash again. It apparently happened earlier in the call chain (so maybe the slub debugging found something), which should be good. Except it now happens in a context where I just see a hung machine, and nothing makes it onto the screen or into the logs ;( So this thing is apparently not all that hard to trigger, but it doesn't exactly seem easy either. It tends to happen fairly soon after a reboot, which makes me suspect it's some cold-cache issue, but that doesn't narrow things down as much as you'd think. It could still be the block layer changes, but it could also equally well be the ext4 changes. I don't think there's any splice activity anywhere, but who knows. And the splice changes could have buggered the pipe locking, so.. Anyway, I don't think I can bisect it, but I'll try to narrow it down a *bit* at least. Not doing any more pulls on this unstable base, I've been puttering around in trying to clean up some stupid printk logging issues instead. Linus