From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 26CA5C28CC0 for ; Thu, 30 May 2019 07:44:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF3552568D for ; Thu, 30 May 2019 07:44:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727413AbfE3Hov (ORCPT ); Thu, 30 May 2019 03:44:51 -0400 Received: from mx2.cyber.ee ([193.40.6.72]:37104 "EHLO mx2.cyber.ee" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726027AbfE3Hou (ORCPT ); Thu, 30 May 2019 03:44:50 -0400 Subject: Re: [PATCH] vmalloc: Don't use flush flag when no exec perm To: "Edgecombe, Rick P" , "linux-kernel@vger.kernel.org" , "peterz@infradead.org" , "davem@davemloft.net" , "sparclinux@vger.kernel.org" , "netdev@vger.kernel.org" Cc: "daniel@iogearbox.net" , "jeyu@kernel.org" , "ast@kernel.org" , "ard.biesheuvel@arm.com" , "will.deacon@arm.com" , "namit@vmware.com" , "luto@kernel.org" , "Hansen, Dave" References: <20190529055104.6822-1-rick.p.edgecombe@intel.com> <89d6dee949e4418f0cca4cc6c4c9b526c1a5c497.camel@intel.com> From: Meelis Roos Message-ID: <67241836-621c-6933-1278-f04aedcefcb3@linux.ee> Date: Thu, 30 May 2019 10:44:47 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <89d6dee949e4418f0cca4cc6c4c9b526c1a5c497.camel@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: et-EE Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> The addition of VM_FLUSH_RESET_PERMS for BPF JIT allocations was >> bisected to prevent boot on an UltraSparc III machine. It was found >> that >> sometime shortly after the TLB flush this flag does on vfree of the >> BPF >> program, the machine hung. Further investigation showed that before >> any of >> the changes for this flag were introduced, with >> CONFIG_DEBUG_PAGEALLOC >> configured (which does a similar TLB flush of the vmalloc range on >> every vfree), this machine also hung shortly after the first vmalloc >> unmap/free. >> >> So the evidence points to there being some existing issue with the >> vmalloc TLB flushes, but it's still unknown exactly why these hangs >> are >> happening on sparc. It is also unknown when someone with this >> hardware >> could resolve this, and in the meantime using this flag on it turns a >> lurking behavior into something that prevents boot. > > The sparc TLB flush issue has been bisected and is being worked on now, > so hopefully we won't need this patch: > https://marc.info/?l=linux-sparc&m=155915694304118&w=2 And the sparc64 patch that fixes CONFIG_DEBUG_PAGEALLOC also fixes booting of the latest git kernel on Sun V445 where my problem initially happened. -- Meelis Roos