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=-15.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 B2A07C43461 for ; Tue, 15 Sep 2020 23:48:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7945320809 for ; Tue, 15 Sep 2020 23:48:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600213734; bh=ByQOXLScGAN+9NlFCb8SEXCejk2L6A0XCMxzOSYsSZ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1hwFnP9BVeZxmgyc6oUse0uJO6CXPix9EQhX2z1Ny4gh7Fc/5UcSmlPSiyDs+oF+0 neo4J0l/dvsWNRvVhO7uuikLusGB4ss3CIviPpXNYHy/vi27XmEfS6YeQneu6NAcjA 4qqi+a+IXODR1WL1qntvvbiJ+dBWk3db6+4IkS9s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727406AbgIOXsv (ORCPT ); Tue, 15 Sep 2020 19:48:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:47678 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727096AbgIOOcn (ORCPT ); Tue, 15 Sep 2020 10:32:43 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 64CA123BE2; Tue, 15 Sep 2020 14:24:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600179884; bh=ByQOXLScGAN+9NlFCb8SEXCejk2L6A0XCMxzOSYsSZ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uyhpcV8J73RwwCBOryYohgCcqLaR/AeX01twF5zHtnrrf/8v6+wgEpRDnpR/K7at6 6u9JDdCGh5lj2Z5d2UM6147z1+Rq5t+TZYKz7FLD/2yoA3RJCNrM+ZZfEWqrXSEQKJ mBewnFUfxazH9/Lo5y7Ou2EDm3crNP6M9neW/zmI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= , Mark Brown , Sasha Levin Subject: [PATCH 5.8 005/177] regulator: push allocation in regulator_ena_gpio_request() out of lock Date: Tue, 15 Sep 2020 16:11:16 +0200 Message-Id: <20200915140653.886414386@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200915140653.610388773@linuxfoundation.org> References: <20200915140653.610388773@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michał Mirosław [ Upstream commit 467bf30142c64f2eb64e2ac67fa4595126230efd ] Move another allocation out of regulator_list_mutex-protected region, as reclaim might want to take the same lock. WARNING: possible circular locking dependency detected 5.7.13+ #534 Not tainted ------------------------------------------------------ kswapd0/383 is trying to acquire lock: c0e5d920 (regulator_list_mutex){+.+.}-{3:3}, at: regulator_lock_dependent+0x54/0x2c0 but task is already holding lock: c0e38518 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x50 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: fs_reclaim_acquire.part.11+0x40/0x50 fs_reclaim_acquire+0x24/0x28 kmem_cache_alloc_trace+0x40/0x1e8 regulator_register+0x384/0x1630 devm_regulator_register+0x50/0x84 reg_fixed_voltage_probe+0x248/0x35c [...] other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(regulator_list_mutex); lock(fs_reclaim); lock(regulator_list_mutex); *** DEADLOCK *** [...] 2 locks held by kswapd0/383: #0: c0e38518 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x50 #1: cb70e5e0 (hctx->srcu){....}-{0:0}, at: hctx_lock+0x60/0xb8 [...] Fixes: 541d052d7215 ("regulator: core: Only support passing enable GPIO descriptors") [this commit only changes context] Fixes: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking") [this is when the regulator_list_mutex was introduced in reclaim locking path] Signed-off-by: Michał Mirosław Link: https://lore.kernel.org/r/41fe6a9670335721b48e8f5195038c3d67a3bf92.1597195321.git.mirq-linux@rere.qmqm.pl Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/regulator/core.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 720f28844795b..86107d2e1733e 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -2222,10 +2222,13 @@ EXPORT_SYMBOL_GPL(regulator_bulk_unregister_supply_alias); static int regulator_ena_gpio_request(struct regulator_dev *rdev, const struct regulator_config *config) { - struct regulator_enable_gpio *pin; + struct regulator_enable_gpio *pin, *new_pin; struct gpio_desc *gpiod; gpiod = config->ena_gpiod; + new_pin = kzalloc(sizeof(*new_pin), GFP_KERNEL); + + mutex_lock(®ulator_list_mutex); list_for_each_entry(pin, ®ulator_ena_gpio_list, list) { if (pin->gpiod == gpiod) { @@ -2234,9 +2237,13 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev, } } - pin = kzalloc(sizeof(struct regulator_enable_gpio), GFP_KERNEL); - if (pin == NULL) + if (new_pin == NULL) { + mutex_unlock(®ulator_list_mutex); return -ENOMEM; + } + + pin = new_pin; + new_pin = NULL; pin->gpiod = gpiod; list_add(&pin->list, ®ulator_ena_gpio_list); @@ -2244,6 +2251,10 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev, update_ena_gpio_to_rdev: pin->request_count++; rdev->ena_pin = pin; + + mutex_unlock(®ulator_list_mutex); + kfree(new_pin); + return 0; } @@ -5137,9 +5148,7 @@ regulator_register(const struct regulator_desc *regulator_desc, } if (config->ena_gpiod) { - mutex_lock(®ulator_list_mutex); ret = regulator_ena_gpio_request(rdev, config); - mutex_unlock(®ulator_list_mutex); if (ret != 0) { rdev_err(rdev, "Failed to request enable GPIO: %d\n", ret); -- 2.25.1