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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 643A9C3B1B5 for ; Fri, 14 Feb 2020 18:14:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B180222C2 for ; Fri, 14 Feb 2020 18:14:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581704044; bh=deNAJfb+HengsUnbWaZWDBpg7gTmWXmNHJ17KELUfr4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=d1qMnvcd+OVVVidV4Ehq3FFG8RCkyvsPVLZbjaBPrk2c5Qw0+u4pClH1ZMER5dMR1 /Z3A34GwJCRq+Lpb4csIy/4cGT7lgQbDGKrqQvH1hBVq/ODOnajLeWOUXxqLjKN1Bl v13NjvxcytbrgGSFFNVMkj0quiLPnNcUQwIGUEVU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731021AbgBNPwi (ORCPT ); Fri, 14 Feb 2020 10:52:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:59076 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731018AbgBNPwi (ORCPT ); Fri, 14 Feb 2020 10:52:38 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6A77224676; Fri, 14 Feb 2020 15:52:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581695557; bh=deNAJfb+HengsUnbWaZWDBpg7gTmWXmNHJ17KELUfr4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tHwq/1oon3DHLu7R8SeMY2V94QOfzouF17aXsLfJ3Y2rGaCpYRtbyscd6J6RPuIF7 hPQzJI4liadweaHlXLRW3bLArY+7uNTUnpmiPALT8RiTry1OojJsLRXTTMDFFOwqKA 92gxfKEds8WSV+8G6t1nyII1KKyov78AD3DCUA+k= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Masami Hiramatsu , Jessica Yu , Sasha Levin Subject: [PATCH AUTOSEL 5.5 171/542] modules: lockdep: Suppress suspicious RCU usage warning Date: Fri, 14 Feb 2020 10:42:43 -0500 Message-Id: <20200214154854.6746-171-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200214154854.6746-1-sashal@kernel.org> References: <20200214154854.6746-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Masami Hiramatsu [ Upstream commit bf08949cc8b98b7d1e20cfbba169a5938d42dae8 ] While running kprobe module test, find_module_all() caused a suspicious RCU usage warning. ----- ============================= WARNING: suspicious RCU usage 5.4.0-next-20191202+ #63 Not tainted ----------------------------- kernel/module.c:619 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by rmmod/642: #0: ffffffff8227da80 (module_mutex){+.+.}, at: __x64_sys_delete_module+0x9a/0x230 stack backtrace: CPU: 0 PID: 642 Comm: rmmod Not tainted 5.4.0-next-20191202+ #63 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0x71/0xa0 find_module_all+0xc1/0xd0 __x64_sys_delete_module+0xac/0x230 ? do_syscall_64+0x12/0x1f0 do_syscall_64+0x50/0x1f0 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4b6d49 ----- This is because list_for_each_entry_rcu(modules) is called without rcu_read_lock(). This is safe because the module_mutex is locked. Pass lockdep_is_held(&module_mutex) to the list_for_each_entry_rcu() to suppress this warning, This also fixes similar issue in mod_find() and each_symbol_section(). Signed-off-by: Masami Hiramatsu Signed-off-by: Jessica Yu Signed-off-by: Sasha Levin --- kernel/module.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 8785e31c2dd0f..d83edc3a41a33 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -214,7 +214,8 @@ static struct module *mod_find(unsigned long addr) { struct module *mod; - list_for_each_entry_rcu(mod, &modules, list) { + list_for_each_entry_rcu(mod, &modules, list, + lockdep_is_held(&module_mutex)) { if (within_module(addr, mod)) return mod; } @@ -448,7 +449,8 @@ bool each_symbol_section(bool (*fn)(const struct symsearch *arr, if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data)) return true; - list_for_each_entry_rcu(mod, &modules, list) { + list_for_each_entry_rcu(mod, &modules, list, + lockdep_is_held(&module_mutex)) { struct symsearch arr[] = { { mod->syms, mod->syms + mod->num_syms, mod->crcs, NOT_GPL_ONLY, false }, @@ -616,7 +618,8 @@ static struct module *find_module_all(const char *name, size_t len, module_assert_mutex_or_preempt(); - list_for_each_entry_rcu(mod, &modules, list) { + list_for_each_entry_rcu(mod, &modules, list, + lockdep_is_held(&module_mutex)) { if (!even_unformed && mod->state == MODULE_STATE_UNFORMED) continue; if (strlen(mod->name) == len && !memcmp(mod->name, name, len)) -- 2.20.1