Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932446Ab2KZSIV (ORCPT ); Mon, 26 Nov 2012 13:08:21 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:47360 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932337Ab2KZREL (ORCPT ); Mon, 26 Nov 2012 12:04:11 -0500 From: Herton Ronaldo Krzesinski To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Masami Hiramatsu , "David S. Miller" , Jason Wessel , Herton Ronaldo Krzesinski Subject: [PATCH 070/270] mips,kgdb: fix recursive page fault with CONFIG_KPROBES Date: Mon, 26 Nov 2012 14:56:00 -0200 Message-Id: <1353949160-26803-71-git-send-email-herton.krzesinski@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1353949160-26803-1-git-send-email-herton.krzesinski@canonical.com> References: <1353949160-26803-1-git-send-email-herton.krzesinski@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1928 Lines: 59 3.5.7u1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Wessel commit f0a996eeeda214f4293e234df33b29bec003b536 upstream. This fault was detected using the kgdb test suite on boot and it crashes recursively due to the fact that CONFIG_KPROBES on mips adds an extra die notifier in the page fault handler. The crash signature looks like this: kgdbts:RUN bad memory access test KGDB: re-enter exception: ALL breakpoints killed Call Trace: [<807b7548>] dump_stack+0x20/0x54 [<807b7548>] dump_stack+0x20/0x54 The fix for now is to have kgdb return immediately if the fault type is DIE_PAGE_FAULT and allow the kprobe code to decide what is supposed to happen. Cc: Masami Hiramatsu Cc: David S. Miller Signed-off-by: Jason Wessel Signed-off-by: Herton Ronaldo Krzesinski --- arch/mips/kernel/kgdb.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c index f4546e9..23817a6 100644 --- a/arch/mips/kernel/kgdb.c +++ b/arch/mips/kernel/kgdb.c @@ -283,6 +283,15 @@ static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd, struct pt_regs *regs = args->regs; int trap = (regs->cp0_cause & 0x7c) >> 2; +#ifdef CONFIG_KPROBES + /* + * Return immediately if the kprobes fault notifier has set + * DIE_PAGE_FAULT. + */ + if (cmd == DIE_PAGE_FAULT) + return NOTIFY_DONE; +#endif /* CONFIG_KPROBES */ + /* Userspace events, ignore. */ if (user_mode(regs)) return NOTIFY_DONE; -- 1.7.9.5 -- 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/