From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28esmtp02.in.ibm.com (e28smtp02.in.ibm.com [59.145.155.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e28smtp02.in.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 9530DDE2B9 for ; Wed, 27 Aug 2008 21:12:32 +1000 (EST) Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by e28esmtp02.in.ibm.com (8.13.1/8.13.1) with ESMTP id m7RBCNqP025562 for ; Wed, 27 Aug 2008 16:42:23 +0530 Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m7RBCN4X1716416 for ; Wed, 27 Aug 2008 16:42:23 +0530 Received: from d28av03.in.ibm.com (loopback [127.0.0.1]) by d28av03.in.ibm.com (8.13.1/8.13.3) with ESMTP id m7RBCMuS016787 for ; Wed, 27 Aug 2008 16:42:22 +0530 Message-ID: <48B53695.3020703@linux.vnet.ibm.com> Date: Wed, 27 Aug 2008 16:42:21 +0530 From: Kamalesh Babulal MIME-Version: 1.0 To: Arjan van de Ven Subject: Re: [BUG] linux-next: Tree for August 26 - Badness at kernel/notifier.c:25 References: <20080826184008.6be39f19.sfr@canb.auug.org.au> <48B44B2D.8070809@linux.vnet.ibm.com> <48B46610.1010809@linux.intel.com> In-Reply-To: <48B46610.1010809@linux.intel.com> Content-Type: text/plain; charset=ISO-8859-1 Cc: Stephen Rothwell , LKML , linuxppc-dev@ozlabs.org, linux-next@vger.kernel.org, mingo@elte.hu List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Arjan van de Ven wrote: > Kamalesh Babulal wrote: >> Hi Stephen, >> >> Badness warning is seen, while booting up the next-20080825/26 kernels on >> the powerpc boxes >> > > this is fixed in the patch I sent to Ingo earlier today > (attached again for reference) > > > ------------------------------------------------------------------------ > > From eafa461d187448998b1f66c9134e66b125db9531 Mon Sep 17 00:00:00 2001 > From: Arjan van de Ven > Date: Tue, 26 Aug 2008 09:01:06 -0700 > Subject: [PATCH] debug: add notifier chain debugging > > during some development we suspected a case where we left something > in a notifier chain that was from a module that was unloaded already... > and that sort of thing is rather hard to track down. > > This patch adds a very simple sanity check (which isn't all that > expensive) to make sure the notifier we're about to call is > actually from either the kernel itself of from a still-loaded > module, avoiding a hard-to-chase-down crash. > > Signed-off-by: Arjan van de Ven > Acked-by: Tony Luck > --- > include/linux/kernel.h | 3 +++ > kernel/extable.c | 16 ++++++++++++++++ > kernel/notifier.c | 6 ++++++ > lib/vsprintf.c | 2 +- > 4 files changed, 26 insertions(+), 1 deletions(-) > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index 2651f80..4e1366b 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -187,6 +187,9 @@ extern unsigned long long memparse(char *ptr, char **retptr); > extern int core_kernel_text(unsigned long addr); > extern int __kernel_text_address(unsigned long addr); > extern int kernel_text_address(unsigned long addr); > +extern int func_ptr_is_kernel_text(void *ptr); > +extern void *dereference_function_descriptor(void *ptr); > + > struct pid; > extern struct pid *session_of_pgrp(struct pid *pgrp); > > diff --git a/kernel/extable.c b/kernel/extable.c > index a26cb2e..adf0cc9 100644 > --- a/kernel/extable.c > +++ b/kernel/extable.c > @@ -66,3 +66,19 @@ int kernel_text_address(unsigned long addr) > return 1; > return module_text_address(addr) != NULL; > } > + > +/* > + * On some architectures (PPC64, IA64) function pointers > + * are actually only tokens to some data that then holds the > + * real function address. As a result, to find if a function > + * pointer is part of the kernel text, we need to do some > + * special dereferencing first. > + */ > +int func_ptr_is_kernel_text(void *ptr) > +{ > + unsigned long addr; > + addr = (unsigned long) dereference_function_descriptor(ptr); > + if (core_kernel_text(addr)) > + return 1; > + return module_text_address(addr) != NULL; > +} > diff --git a/kernel/notifier.c b/kernel/notifier.c > index 823be11..522277c 100644 > --- a/kernel/notifier.c > +++ b/kernel/notifier.c > @@ -82,6 +82,12 @@ static int __kprobes notifier_call_chain(struct notifier_block **nl, > > while (nb && nr_to_call) { > next_nb = rcu_dereference(nb->next); > + if (!func_ptr_is_kernel_text(nb->notifier_call)) { > + WARN(1, "Invalid notifier called!"); > + nb = next_nb; > + continue; > + } > + > ret = nb->notifier_call(nb, val, v); > > if (nr_calls) > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index d8d1d11..f5e5ffb 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -513,7 +513,7 @@ static char *string(char *buf, char *end, char *s, int field_width, int precisio > return buf; > } > > -static inline void *dereference_function_descriptor(void *ptr) > +void *dereference_function_descriptor(void *ptr) > { > #if defined(CONFIG_IA64) || defined(CONFIG_PPC64) > void *p; Thanks for reference of the patch, After replacing the patch with the latest one above on the powerpc, the warning still remains Badness at kernel/notifier.c:86 NIP: c000000000081470 LR: c000000000081494 CTR: c00000000005a2d0 REGS: c0000021ce0bfaf0 TRAP: 0700 Not tainted (2.6.27-rc4-next-20080826-autotest) MSR: 8000000000029032 CR: 24008042 XER: 00000005 TASK = c0000015de080000[1] 'swapper' THREAD: c0000021ce0bc000 CPU: 0 GPR00: c000000000081494 c0000021ce0bfd70 c00000000081e940 c000000000749c38 GPR04: 0000000000000003 0000000000000001 ffffffffffffffff c0000021ce0bfe90 GPR08: ffffffffffffffff ffffffffffffffff c0000000004fd9f0 c0000000004fd9f0 GPR12: 0000000024000042 c00000000089c300 0000000002307ef0 c0000000006332a0 GPR16: c000000000631f28 c000000000633388 00000000018bf8b0 0000000002700000 GPR20: c00000000070b07c c000000000707ef0 c000000000708160 c000000000631c58 GPR24: 0000000000000003 0000000000000001 c0000021ce0bfe90 0000000000000000 GPR28: ffffffffffffffff c000000000749c20 c0000000007bf338 c000000000749c38 NIP [c000000000081470] .notifier_call_chain+0x70/0x140 LR [c000000000081494] .notifier_call_chain+0x94/0x140 Call Trace: [c0000021ce0bfd70] [c000000000081494] .notifier_call_chain+0x94/0x140 (unreliable) [c0000021ce0bfe20] [c0000000004fe3fc] .cpu_up+0x10c/0x200 [c0000021ce0bfee0] [c0000000006cdcc0] .kernel_init+0x1b0/0x440 [c0000021ce0bff90] [c0000000000299cc] .kernel_thread+0x4c/0x68 Instruction dump: e8630000 2fa30000 419e00f0 2fa60000 419e00e8 2e270000 7c7f1b78 3b600000 48000028 60000000 60000000 60000000 <0fe00000> 2fbd0000 2f3c0000 7fbfeb78 -- Thanks & Regards, Kamalesh Babulal, Linux Technology Center, IBM, ISTL.