From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753899AbbEDMuk (ORCPT ); Mon, 4 May 2015 08:50:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48311 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753828AbbEDMuF (ORCPT ); Mon, 4 May 2015 08:50:05 -0400 Date: Mon, 4 May 2015 14:49:22 +0200 From: Oleg Nesterov To: Ananth N Mavinakayanahalli , Anton Arapov , David Long , Denys Vlasenko , "Frank Ch. Eigler" , Ingo Molnar , Jan Willeke , Jim Keniston , Mark Wielaard , Pratyush Anand , Srikar Dronamraju Cc: linux-kernel@vger.kernel.org Subject: [PATCH 09/10] uprobes: Change prepare_uretprobe() to (try to) flush the dead frames Message-ID: <20150504124922.GA22522@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150504124835.GA22462@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Change prepare_uretprobe() to flush the !arch_uretprobe_is_alive() return_instance's. This is not needed correctness-wise, but can help to avoid the failure caused by MAX_URETPROBE_DEPTH. Note: in this case arch_uretprobe_is_alive() can be false positive, the stack can grow after longjmp(). Unfortunately, the kernel can't 100% solve this problem, but see the next patch. Signed-off-by: Oleg Nesterov --- kernel/events/uprobes.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 0dd7ff7..b6433fb 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1522,6 +1522,16 @@ static unsigned long get_trampoline_vaddr(void) return trampoline_vaddr; } +static void cleanup_return_instances(struct uprobe_task *utask, struct pt_regs *regs) +{ + struct return_instance *ri = utask->return_instances; + while (ri && !arch_uretprobe_is_alive(&ri->auret, regs)) { + ri = free_ret_instance(ri); + utask->depth--; + } + utask->return_instances = ri; +} + static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) { struct return_instance *ri; @@ -1576,6 +1586,9 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) ri->orig_ret_vaddr = orig_ret_vaddr; ri->chained = chained; + if (utask->depth) /* drop the entries invalidated by longjmp() */ + cleanup_return_instances(utask, regs); + utask->depth++; ri->next = utask->return_instances; utask->return_instances = ri; -- 1.5.5.1