From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1A3FC43457 for ; Mon, 19 Oct 2020 08:36:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B1B622225A for ; Mon, 19 Oct 2020 08:36:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603096617; bh=aJnlzjBng/UTUZpHV3Dd58u0QZTex9ib4lQidmOyfJA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=PshiMH2OHiNv85WtFvPMKj9DWD3cD1JT6fEor+FZisZSXx+IwbOLzLyl+ebQaMHJz GToiCHZ/CV8eSBsHADeMVZIDDK0P4fKc3unIz4ZLjSNp+RQ83crmi9U8xH9rmIWD5M YckkggT6YNs69VWeiMcoFsZIzWVgD0BFN5CXnsUg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729353AbgJSIgz (ORCPT ); Mon, 19 Oct 2020 04:36:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:58212 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729315AbgJSIgz (ORCPT ); Mon, 19 Oct 2020 04:36:55 -0400 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 401A122268; Mon, 19 Oct 2020 08:36:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603096614; bh=aJnlzjBng/UTUZpHV3Dd58u0QZTex9ib4lQidmOyfJA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=oFgNIQpfs1sDGlluLXCWG/MIARFOohhgFUsbXAhcQAFJeI/sP7XaaaDCmZNy+DOdm ukKR6XAmqGzCnTRxsEsGiCBZSLi/suW1mzHGRmP3yZcF4bQSCrQdM0Rs8QC8c2OamS HMvYRxRzQK70G9ElOmo1eCtExMLnLnYIIArC2o60= Date: Mon, 19 Oct 2020 17:36:48 +0900 From: Masami Hiramatsu To: guoren@kernel.org Cc: palmerdabbelt@google.com, paul.walmsley@sifive.com, alankao@andestech.com, rostedt@goodmis.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, anup@brainfault.org, linux-csky@vger.kernel.org, greentime.hu@sifive.com, zong.li@sifive.com, me@packi.ch, Guo Ren Subject: Re: [PATCH v4 9/9] riscv: Fixup lockdep_assert_held(&text_mutex) in patch_insn_write Message-Id: <20201019173648.573d58c7fde864090bf0487a@kernel.org> In-Reply-To: <1602918377-23573-10-git-send-email-guoren@kernel.org> References: <1602918377-23573-1-git-send-email-guoren@kernel.org> <1602918377-23573-10-git-send-email-guoren@kernel.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 17 Oct 2020 07:06:17 +0000 guoren@kernel.org wrote: > From: Guo Ren > > It will cause warning messages: > echo function_graph > /sys/kernel/debug/tracing/current_tracer > [ 47.691397] ------------[ cut here ]------------ > [ 47.692899] WARNING: CPU: 0 PID: 11 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x182/0x19a > [ 47.694483] Modules linked in: > [ 47.695754] CPU: 0 PID: 11 Comm: migration/0 Not tainted 5.9.0-11367-g1054335 #132 > [ 47.698228] epc: ffffffe000204530 ra : ffffffe00020452c sp : ffffffe0023ffc20 gp : ffffffe0013e1fe0 tp : ffffffe0023e4e00 t0 : 0000000000000000 > [ 47.701872] t1 : 000000000000000e t2 : 000000000000001b s0 : ffffffe0023ffc70 s1 : ffffffe000206850 a0 : 0000000000000000 a1 : ffffffffffffffff > [ 47.705550] a2 : 0000000000000000 a3 : ffffffe03af7c5e8 a4 : 0000000000000000 a5 : 0000000000000000 a6 : 0000000000000000 a7 : 00000000150b02d8 > [ 47.709159] s2 : 0000000000000008 s3 : 0000000000000858 s4 : ffffffe0023ffc98 s5 : 0000000000000850 s6 : 0000000000000003 s7 : 0000000000000002 > [ 47.714135] s8 : 0000000000000004 s9 : 0000000000000001 s10: 0000000000000001 s11: 0000000000000003 t3 : ffffffffffffe000 t4 : 0000000000d86254 > [ 47.716574] t5 : 0000000000000005 t6 : 0000000000040000status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003 > [ 47.720019] CPU: 0 PID: 11 Comm: migration/0 Not tainted 5.9.0-11367-g1054335 #132 > [ 47.722074] Call Trace: > [ 47.722561] [] walk_stackframe+0x0/0xc2 > [ 47.724608] [] show_stack+0x46/0x52 > [ 47.726246] [] dump_stack+0x90/0xb6 > [ 47.727672] [] __warn+0x98/0xfa > [ 47.729131] [] report_bug+0xaa/0x11e > [ 47.730624] [] do_trap_break+0x96/0xfe > [ 47.732448] [] ret_from_exception+0x0/0x14 > [ 47.734341] [] patch_insn_write+0x17e/0x19a > [ 47.737235] irq event stamp: 39 > [ 47.738521] hardirqs last enabled at (39): [] _save_context+0xa2/0xe6 > [ 47.741055] hardirqs last disabled at (38): [] multi_cpu_stop+0x130/0x166 > [ 47.743551] softirqs last enabled at (0): [] copy_process+0x430/0x1316 > [ 47.746031] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 47.748617] ---[ end trace 88a1054faa6524ef ]--- > > Because the path of stop_machine(__ftrace_modify_code)-> > ftrace_modify_all_code->...->patch_insn_write has no pair of > lock&unlock text_mutex, so we shouldn't put assert here. Hm, are there any chance to get the text_mutex in that path? There are ftrace_arch_code_modify_prepare/post_process() in arch/riscv/kernel/ftrace.c, aren't those used? Thank you, > > Signed-off-by: Guo Ren > --- > arch/riscv/kernel/patch.c | 7 ------- > 1 file changed, 7 deletions(-) > > diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c > index 0b55287..2ee5063 100644 > --- a/arch/riscv/kernel/patch.c > +++ b/arch/riscv/kernel/patch.c > @@ -55,13 +55,6 @@ static int patch_insn_write(void *addr, const void *insn, size_t len) > bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; > int ret; > > - /* > - * Before reaching here, it was expected to lock the text_mutex > - * already, so we don't need to give another lock here and could > - * ensure that it was safe between each cores. > - */ > - lockdep_assert_held(&text_mutex); > - > if (across_pages) > patch_map(addr + len, FIX_TEXT_POKE1); > > -- > 2.7.4 > -- Masami Hiramatsu