Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756723AbaKTABT (ORCPT ); Wed, 19 Nov 2014 19:01:19 -0500 Received: from www.linutronix.de ([62.245.132.108]:48314 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755100AbaKTAA6 (ORCPT ); Wed, 19 Nov 2014 19:00:58 -0500 Date: Thu, 20 Nov 2014 01:00:51 +0100 (CET) From: Thomas Gleixner To: Andy Lutomirski cc: Frederic Weisbecker , Linus Torvalds , Dave Jones , Don Zickus , Linux Kernel , the arch/x86 maintainers , Peter Zijlstra , Arnaldo Carvalho de Melo Subject: Re: frequent lockups in 3.18rc4 In-Reply-To: Message-ID: References: <20141118145234.GA7487@redhat.com> <20141118215540.GD35311@redhat.com> <20141119021902.GA14216@redhat.com> <20141119145902.GA13387@redhat.com> <20141119190215.GA10796@lerouge> <20141119225615.GA11386@lerouge> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Nov 2014, Andy Lutomirski wrote: > On Wed, Nov 19, 2014 at 3:09 PM, Thomas Gleixner wrote: > > Sorry, I can't follow your argumentation here. > > > > pcpu_alloc() > > .... > > area_found: > > .... > > > > /* clear the areas and return address relative to base address */ > > for_each_possible_cpu(cpu) > > memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size); > > > > How would that memset fail to establish the mapping, which is > > btw. already established via: > > > > pcpu_populate_chunk() > > > > already before that memset? > > I think that this will map them into init_mm->pgd and > current->active_mm->pgd, but it won't necessarily map them into the > rest of the pgds. And why would mapping them into the kernel mapping, i.e. init_mm not be sufficient? We are talking about kernel memory and not some random user space mapping. Thanks, tglx -- 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/