Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933907Ab3JOUjK (ORCPT ); Tue, 15 Oct 2013 16:39:10 -0400 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.226]:8917 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933584Ab3JOUjI (ORCPT ); Tue, 15 Oct 2013 16:39:08 -0400 Date: Tue, 15 Oct 2013 16:39:06 -0400 From: Steven Rostedt To: LKML Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Frederic Weisbecker , Andrew Morton , "paulmck@linux.vnet.ibm.com" , Peter Zijlstra , "x86@kernel.org" , "Wang, Xiaoming" , "Li, Zhuangzhi" , "Liu, Chuansheng" Subject: [PATCH] x86: Remove WARN_ON(in_nmi()) from vmalloc_fault Message-ID: <20131015163906.342d8ffa@gandalf.local.home> X-Mailer: Claws Mail 3.9.2 (GTK+ 2.24.20; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.142:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1353 Lines: 37 Since the NMI iretq nesting has been fixed, there's no reason that an NMI handler can not take a page fault for vmalloc'd code. No locks are taken in that code path, and the software now handles nested NMIs when the fault re-enables NMIs on iretq. Not only that, if the vmalloc_fault() WARN_ON_ONCE() is hit, and that warn on triggers a vmalloc fault for some reason, then we can go into an infinite loop (the WARN_ON_ONCE() does the WARN() before updating the variable to make it happen "once"). Reported-by: "Liu, Chuansheng" Signed-off-by: Steven Rostedt --- arch/x86/mm/fault.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 3aaeffc..78926c6 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -268,8 +268,6 @@ static noinline __kprobes int vmalloc_fault(unsigned long address) if (!(address >= VMALLOC_START && address < VMALLOC_END)) return -1; - WARN_ON_ONCE(in_nmi()); - /* * Synchronize this task's top level page-table * with the 'reference' page table. -- 1.8.1.4 -- 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/