From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: BUG: unable to handle kernel NULL pointer dereference on 3.18.13-rt10 Date: Mon, 13 Jul 2015 11:12:37 +0200 Message-ID: <20150713091237.GA31747@linutronix.de> References: <453aa7881ded41e7a843795863ac1712@FE-MBX1012.de.bosch.com> <20150710132318.GA27402@linutronix.de> <3c9ae4a1f9cb4ac3a96a28c3f65f9442@FE-MBX1012.de.bosch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Thomas Gleixner , "linux-rt-users@vger.kernel.org" To: "Koehrer Mathias (ETAS/ESW5)" , Steven Rostedt Return-path: Received: from www.linutronix.de ([62.245.132.108]:52730 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750810AbbGMJMj convert rfc822-to-8bit (ORCPT ); Mon, 13 Jul 2015 05:12:39 -0400 Content-Disposition: inline In-Reply-To: <3c9ae4a1f9cb4ac3a96a28c3f65f9442@FE-MBX1012.de.bosch.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: * Koehrer Mathias (ETAS/ESW5) | 2015-07-13 06:18:22 [+0000]: >> if you managed to trigger it that reliably, could you revert >> slub_delay_ctor_on_rt.patch in the queue and try again? >>=20 >Over the weekend I ran a test that rebooted the PC permanently. >After about 400 reboots I got another NULL pointer dereference.=20 >However the slub_delay_ctor_on_rt.patch has not been reverted yet. >And: This looks somehow differently than the previous BUGs. > > >[ 3.299329] BUG: unable to handle kernel NULL pointer dereference a= t 0000008c >[ 3.299332] IP: [] function_trace_call+0xc/0x190 This is=20 | static void | function_trace_call(unsigned long ip, unsigned long parent_ip, | struct ftrace_ops *op, struct pt_regs *pt_regs) | { | struct trace_array *tr =3D op->private; |=E2=80=A6 |=20 | if (unlikely(!tr->function_enabled)) | return; and it looks like tr is null. BUG_ON(!tr) should prove this. Steven, is it somehow possible that on module load we get "op" set without its private member initialized? Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html