Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756559Ab3FCKS0 (ORCPT ); Mon, 3 Jun 2013 06:18:26 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:33965 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755503Ab3FCKSX (ORCPT ); Mon, 3 Jun 2013 06:18:23 -0400 Date: Mon, 3 Jun 2013 11:18:09 +0100 From: Russell King - ARM Linux To: Will Deacon Cc: "Wang, Yalin" , "'richard -rw- weinberger'" , "'linux-arch@vger.kernel.org'" , "'linux-kernel@vger.kernel.org'" , "'linux-arm-kernel@lists.infradead.org'" Subject: Re: A bug about system call on ARM Message-ID: <20130603101809.GK18614@n2100.arm.linux.org.uk> References: <35FD53F367049845BC99AC72306C23D1610991B85B@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D1610991B85D@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D1610991B85E@CNBJMBX05.corpusers.net> <20130529094826.GD13095@mudshark.cambridge.arm.com> <35FD53F367049845BC99AC72306C23D1610991B865@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D1610991B866@CNBJMBX05.corpusers.net> <20130530090949.GC7483@mudshark.cambridge.arm.com> <20130530114112.GH7483@mudshark.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130530114112.GH7483@mudshark.cambridge.arm.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1165 Lines: 29 On Thu, May 30, 2013 at 12:41:12PM +0100, Will Deacon wrote: > +#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) > + /* > + * We may have faulted trying to load the SWI instruction due to > + * concurrent page aging on another CPU. In this case, return > + * back to the swi instruction and fault the page back. > + */ > +9001: > + sub lr, lr, #4 > + str lr, [sp, #S_PC] > + b ret_fast_syscall > +#endif The comment is wrong. If we get here, it means that the fault from trying to loading the instruction can't be fixed up. Arguably, that should result in a SIGSEGV being sent immediately, but we'll get to that when we then try to re-load the instruction. What it means is that the page we were trying to execute has been unmapped beneath us. BTW, I notice that the kernel oops was never posted to the list, so it's impossible for other people following this thread to see what the real problem is... -- 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/