From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755883AbYKWQd2 (ORCPT ); Sun, 23 Nov 2008 11:33:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751407AbYKWQdS (ORCPT ); Sun, 23 Nov 2008 11:33:18 -0500 Received: from fk-out-0910.google.com ([209.85.128.187]:3748 "EHLO fk-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750871AbYKWQdR (ORCPT ); Sun, 23 Nov 2008 11:33:17 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :content-type:content-transfer-encoding; b=fSioA06uBvNoAkniHUts8L1+uEqOble9tGYSs7I06AoY2lbvrUwSm91HnzwWzXUPWO dnkTKlk7dKdKSz9b6xqOdOVI+qTBniLTOhZhKmA+khuQUW6jRyn+/0ECjteV6OTDGt6o UQMjF8XQRVceOF//u4cZfLG507+6YjhcQQmdA= Message-ID: <492985C8.7070205@gmail.com> Date: Sun, 23 Nov 2008 17:33:12 +0100 From: Frederic Weisbecker User-Agent: Thunderbird 2.0.0.17 (X11/20080925) MIME-Version: 1.0 To: Ingo Molnar CC: Steven Rostedt , Linux Kernel Subject: [PATCH] tracing/function-return-tracer: don't trace kfree while it frees the return stack Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Impact: fix a crash While I killed the cat process, I got sometimes the following (but rare) crash: [ 65.689027] Pid: 2969, comm: cat Not tainted (2.6.28-rc6-tip #83) AMILO Li 2727 [ 65.689027] EIP: 0060:[<00000000>] EFLAGS: 00010082 CPU: 1 [ 65.689027] EIP is at 0x0 [ 65.689027] EAX: 00000000 EBX: f66cd780 ECX: c019a64a EDX: f66cd780 [ 65.689027] ESI: 00000286 EDI: f66cd780 EBP: f630be2c ESP: f630be24 [ 65.689027] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 [ 65.689027] Process cat (pid: 2969, ti=f630a000 task=f66cd780 task.ti=f630a000) [ 65.689027] Stack: [ 65.689027] 00000012 f630bd54 f630be7c c012c853 00000000 c0133cc9 f66cda54 f630be5c [ 65.689027] f630be68 f66cda54 f66cd88c f66cd878 f7070000 00000001 f630be90 c0135dbc [ 65.689027] f614a614 f630be68 f630be68 f65ba200 00000002 f630bf10 f630be90 c012cad6 [ 65.689027] Call Trace: [ 65.689027] [] ? do_exit+0x603/0x850 [ 65.689027] [] ? next_signal+0x9/0x40 [ 65.689027] [] ? dequeue_signal+0x8c/0x180 [ 65.689027] [] ? do_group_exit+0x36/0x90 [ 65.689027] [] ? get_signal_to_deliver+0x20c/0x390 [ 65.689027] [] ? do_notify_resume+0x99/0x8b0 [ 65.689027] [] ? tty_ldisc_deref+0x5a/0x80 [ 65.689027] [] ? trace_hardirqs_on+0xb/0x10 [ 65.689027] [] ? tty_ldisc_deref+0x5a/0x80 [ 65.689027] [] ? n_tty_write+0x0/0x340 [ 65.689027] [] ? redirected_tty_write+0x82/0x90 [ 65.689027] [] ? vfs_write+0x99/0xd0 [ 65.689027] [] ? redirected_tty_write+0x0/0x90 [ 65.689027] [] ? sys_write+0x42/0x70 [ 65.689027] [] ? work_notifysig+0x13/0x19 [ 65.689027] Code: Bad EIP value. [ 65.689027] EIP: [<00000000>] 0x0 SS:ESP 0068:f630be24 This is because on do_exit(), kfree is called to free the return addresses stack but kfree is traced and stored its return address in this stack. This patch fixes it. Signed-off-by: Frederic Weisbecker diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 90d99fb..ffff7ec 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1628,8 +1628,9 @@ void ftrace_retfunc_init_task(struct task_struct *t) void ftrace_retfunc_exit_task(struct task_struct *t) { - kfree(t->ret_stack); + struct ftrace_ret_stack *ret_stack = t->ret_stack; t->ret_stack = NULL; + kfree(ret_stack); } #endif -- 1.5.2.5