From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932205AbbGUNmR (ORCPT ); Tue, 21 Jul 2015 09:42:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51374 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932143AbbGUNmO (ORCPT ); Tue, 21 Jul 2015 09:42:14 -0400 Date: Tue, 21 Jul 2015 15:40:23 +0200 From: Oleg Nesterov To: Ingo Molnar Cc: Andy Lutomirski , Pratyush Anand , Srikar Dronamraju , linux-kernel@vger.kernel.org Subject: [PATCH v3 09/14] uprobes: Change prepare_uretprobe() to (try to) flush the dead frames Message-ID: <20150721134023.GA4776@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150721133945.GA4718@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 Acked-by: Srikar Dronamraju Acked-by: Anton Arapov Tested-by: Pratyush Anand --- 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 93d939c..7e61c8c 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1511,6 +1511,16 @@ 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, 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; @@ -1541,6 +1551,9 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) if (orig_ret_vaddr == -1) goto fail; + /* drop the entries invalidated by longjmp() */ + cleanup_return_instances(utask, regs); + /* * We don't want to keep trampoline address in stack, rather keep the * original return address of first caller thru all the consequent -- 1.5.5.1