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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33295C072A2 for ; Wed, 15 Nov 2023 19:49:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235369AbjKOTtq (ORCPT ); Wed, 15 Nov 2023 14:49:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235373AbjKOTto (ORCPT ); Wed, 15 Nov 2023 14:49:44 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 720C519E for ; Wed, 15 Nov 2023 11:49:41 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0459C433C8; Wed, 15 Nov 2023 19:49:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700077781; bh=z7Z9yZZkftoDIj6SHZQ+ED5/TVcby2v3tAHC1O+Jrpc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=juufLhH8K7A2rUpcgQWO3GXuuY4M3YfYL3jU79YUJ9rsQ2IFh54W2tkn2sXMrHUh8 Zy2pjyyx4CC416muZqrQbwT0BXmHcR6/sx+YenzRYdRDBvx7IqArtzPRQEYFagqSTH sPJLDPPbk/gI2ARSYKWOtuUBQNLS/Q//eT8+BLc0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ira Weiny , Davidlohr Bueso , Dave Jiang , Jonathan Cameron , Dan Williams , Sasha Levin Subject: [PATCH 6.6 494/603] cxl/mem: Fix shutdown order Date: Wed, 15 Nov 2023 14:17:19 -0500 Message-ID: <20231115191646.476040124@linuxfoundation.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231115191613.097702445@linuxfoundation.org> References: <20231115191613.097702445@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams [ Upstream commit 88d3917f82ed4215a2154432c26de1480a61b209 ] Ira reports that removing cxl_mock_mem causes a crash with the following trace: BUG: kernel NULL pointer dereference, address: 0000000000000044 [..] RIP: 0010:cxl_region_decode_reset+0x7f/0x180 [cxl_core] [..] Call Trace: cxl_region_detach+0xe8/0x210 [cxl_core] cxl_decoder_kill_region+0x27/0x40 [cxl_core] cxld_unregister+0x29/0x40 [cxl_core] devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1d2/0x210 bus_remove_device+0xd7/0x150 device_del+0x155/0x3e0 device_unregister+0x13/0x60 devm_release_action+0x4d/0x90 ? __pfx_unregister_port+0x10/0x10 [cxl_core] delete_endpoint+0x121/0x130 [cxl_core] devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1d2/0x210 bus_remove_device+0xd7/0x150 device_del+0x155/0x3e0 ? lock_release+0x142/0x290 cdev_device_del+0x15/0x50 cxl_memdev_unregister+0x54/0x70 [cxl_core] This crash is due to the clearing out the cxl_memdev's driver context (@cxlds) before the subsystem is done with it. This is ultimately due to the region(s), that this memdev is a member, being torn down and expecting to be able to de-reference @cxlds, like here: static int cxl_region_decode_reset(struct cxl_region *cxlr, int count) ... if (cxlds->rcd) goto endpoint_reset; ... Fix it by keeping the driver context valid until memdev-device unregistration, and subsequently the entire stack of related dependencies, unwinds. Fixes: 9cc238c7a526 ("cxl/pci: Introduce cdevm_file_operations") Reported-by: Ira Weiny Reviewed-by: Davidlohr Bueso Reviewed-by: Dave Jiang Reviewed-by: Jonathan Cameron Reviewed-by: Ira Weiny Tested-by: Ira Weiny Signed-off-by: Dan Williams Signed-off-by: Sasha Levin --- drivers/cxl/core/memdev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c index a02061028b710..fed9573cf355e 100644 --- a/drivers/cxl/core/memdev.c +++ b/drivers/cxl/core/memdev.c @@ -559,8 +559,8 @@ static void cxl_memdev_unregister(void *_cxlmd) struct cxl_memdev *cxlmd = _cxlmd; struct device *dev = &cxlmd->dev; - cxl_memdev_shutdown(dev); cdev_device_del(&cxlmd->cdev, dev); + cxl_memdev_shutdown(dev); put_device(dev); } -- 2.42.0