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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 69F09C636C9 for ; Sat, 17 Jul 2021 10:09:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 452946113D for ; Sat, 17 Jul 2021 10:09:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233185AbhGQKMb (ORCPT ); Sat, 17 Jul 2021 06:12:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232993AbhGQKM0 (ORCPT ); Sat, 17 Jul 2021 06:12:26 -0400 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25FDCC06175F for ; Sat, 17 Jul 2021 03:09:29 -0700 (PDT) Received: by mail-pj1-x1031.google.com with SMTP id g4-20020a17090ace84b029017554809f35so10288460pju.5 for ; Sat, 17 Jul 2021 03:09:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=83GbSGpZBfJHGXq15Yg2ngQ7/7/5XwVRHY0b6SDhljI=; b=uyXB+/16nvqrz8OL63K/aowqr/Mq1BwOMmDr72vNEAEScOUTTnm6SSGvF+7rT2Dgcc KAaxegtG0c2E5MqZqFgrQi7mXbG5gTKdIXV1ewE+kqwHm3m/31T6RjUeyzLSEfrgQGe5 oU2E1Ke4aSeZ7P9uNVPxWhRRkcmgVn5AOjrOhRcbVyzcHmjyuipoRoWPK2E2yeYBVvJ/ etVdo8RG4HSWZRau145JybWep6I7xLI1pw+NdAK3m+Wtt6J7Rp4CkKv9NC05XatnC9Xx h9x+XMC3KoTFBdcQQJmkO8uX/FzxE6AUsCeCST/DmMtSIFch2SlP5QpbALz0/ExX+yo7 feOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=83GbSGpZBfJHGXq15Yg2ngQ7/7/5XwVRHY0b6SDhljI=; b=P8wp2PComu6OS25xiKdFpTzYH92QVs+STO47Q4n8+mZuVYtFzEJc7mTvqrFH0xqdSH ibn0knTHxoEPMbO6UmjQDWqUOrkjkqvcwxKCk2xMpVd/8M1EsdCVSy5O/rRRZBKWXV0e lMUm9KmIBdsI2ACw6+nmAylQKUeYLoXVUVQApFK92kge+Lpb2P88rpdR6cJYZPrbhUK1 BZCT+gdhXnANv7NEgLNbfSxV6xu6rh5p/AHHnHMKesF7zGYyUWKTjxB5L3hz9AT7XCVw 94wVo0CiOU6Hqqp9goFVKxL45i003Nn70jnZZ22g48FJCACaGtcXkJTbQOLSBoH6UUnk 2RIw== X-Gm-Message-State: AOAM531tfIdfGVnTMN+gck/PXO9PGCPduQ6U/n166v3htS46glAqS9YE L9J2ziYlkbU9E7RxK0rBU1VF7lejrgCZqFKdT3A= X-Google-Smtp-Source: ABdhPJzLcYMp6ta5QAnBuXu8Uqc4NgXwYejLU9B7Rfgy3g02aqr/l8DR6Z3DASRCSSw/6zqZKTBXUQ== X-Received: by 2002:a17:902:9a8c:b029:113:d891:2eaf with SMTP id w12-20020a1709029a8cb0290113d8912eafmr11286452plp.61.1626516568517; Sat, 17 Jul 2021 03:09:28 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id p24sm13487926pfh.17.2021.07.17.03.09.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Jul 2021 03:09:27 -0700 (PDT) From: Desmond Cheong Zhi Xi To: miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com Cc: Desmond Cheong Zhi Xi , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, Hillf Danton Subject: [PATCH] mtd: fix lock hierarchy in deregister_mtd_blktrans Date: Sat, 17 Jul 2021 18:07:19 +0800 Message-Id: <20210717100719.728829-1-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is a lock hierarchy of major_names_lock --> mtd_table_mutex. One existing chain is as follows: 1. major_names_lock --> loop_ctl_mutex (when blk_request_module calls loop_probe) 2. loop_ctl_mutex --> bdev->bd_mutex (when loop_control_ioctl calls loop_remove, which then calls del_gendisk) 3. bdev->bd_mutex --> mtd_table_mutex (when blkdev_get_by_dev calls __blkdev_get, which then calls blktrans_open) Since unregister_blkdev grabs the major_names_lock, we need to call it outside the critical section for mtd_table_mutex, otherwise we invert the lock hierarchy. Reported-by: Hillf Danton Signed-off-by: Desmond Cheong Zhi Xi --- drivers/mtd/mtd_blkdevs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 7d26cfe24d05..87e26788ef60 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -563,8 +563,8 @@ int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) list_for_each_entry_safe(dev, next, &tr->devs, list) tr->remove_dev(dev); - unregister_blkdev(tr->major, tr->name); mutex_unlock(&mtd_table_mutex); + unregister_blkdev(tr->major, tr->name); BUG_ON(!list_empty(&tr->devs)); return 0; -- 2.25.1 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=-13.7 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 80669C636C9 for ; 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Sat, 17 Jul 2021 03:09:28 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id p24sm13487926pfh.17.2021.07.17.03.09.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Jul 2021 03:09:27 -0700 (PDT) From: Desmond Cheong Zhi Xi To: miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com Cc: Desmond Cheong Zhi Xi , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, Hillf Danton Subject: [PATCH] mtd: fix lock hierarchy in deregister_mtd_blktrans Date: Sat, 17 Jul 2021 18:07:19 +0800 Message-Id: <20210717100719.728829-1-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210717_030930_598958_B4D9493D X-CRM114-Status: GOOD ( 10.42 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org There is a lock hierarchy of major_names_lock --> mtd_table_mutex. One existing chain is as follows: 1. major_names_lock --> loop_ctl_mutex (when blk_request_module calls loop_probe) 2. loop_ctl_mutex --> bdev->bd_mutex (when loop_control_ioctl calls loop_remove, which then calls del_gendisk) 3. bdev->bd_mutex --> mtd_table_mutex (when blkdev_get_by_dev calls __blkdev_get, which then calls blktrans_open) Since unregister_blkdev grabs the major_names_lock, we need to call it outside the critical section for mtd_table_mutex, otherwise we invert the lock hierarchy. Reported-by: Hillf Danton Signed-off-by: Desmond Cheong Zhi Xi --- drivers/mtd/mtd_blkdevs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 7d26cfe24d05..87e26788ef60 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -563,8 +563,8 @@ int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) list_for_each_entry_safe(dev, next, &tr->devs, list) tr->remove_dev(dev); - unregister_blkdev(tr->major, tr->name); mutex_unlock(&mtd_table_mutex); + unregister_blkdev(tr->major, tr->name); BUG_ON(!list_empty(&tr->devs)); return 0; -- 2.25.1 ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/ 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=-13.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED, USER_AGENT_GIT autolearn=ham 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 CA349C636C9 for ; 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Sat, 17 Jul 2021 03:09:28 -0700 (PDT) Received: from localhost.localdomain ([118.200.190.93]) by smtp.gmail.com with ESMTPSA id p24sm13487926pfh.17.2021.07.17.03.09.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Jul 2021 03:09:27 -0700 (PDT) From: Desmond Cheong Zhi Xi To: miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com Subject: [PATCH] mtd: fix lock hierarchy in deregister_mtd_blktrans Date: Sat, 17 Jul 2021 18:07:19 +0800 Message-Id: <20210717100719.728829-1-desmondcheongzx@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Cc: Hillf Danton , linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, Desmond Cheong Zhi Xi , linux-kernel-mentees@lists.linuxfoundation.org X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" There is a lock hierarchy of major_names_lock --> mtd_table_mutex. One existing chain is as follows: 1. major_names_lock --> loop_ctl_mutex (when blk_request_module calls loop_probe) 2. loop_ctl_mutex --> bdev->bd_mutex (when loop_control_ioctl calls loop_remove, which then calls del_gendisk) 3. bdev->bd_mutex --> mtd_table_mutex (when blkdev_get_by_dev calls __blkdev_get, which then calls blktrans_open) Since unregister_blkdev grabs the major_names_lock, we need to call it outside the critical section for mtd_table_mutex, otherwise we invert the lock hierarchy. Reported-by: Hillf Danton Signed-off-by: Desmond Cheong Zhi Xi --- drivers/mtd/mtd_blkdevs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 7d26cfe24d05..87e26788ef60 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -563,8 +563,8 @@ int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) list_for_each_entry_safe(dev, next, &tr->devs, list) tr->remove_dev(dev); - unregister_blkdev(tr->major, tr->name); mutex_unlock(&mtd_table_mutex); + unregister_blkdev(tr->major, tr->name); BUG_ON(!list_empty(&tr->devs)); return 0; -- 2.25.1 _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees