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 8689CC433EF for ; Sun, 23 Jan 2022 14:25:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233519AbiAWOZk (ORCPT ); Sun, 23 Jan 2022 09:25:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51044 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232290AbiAWOZj (ORCPT ); Sun, 23 Jan 2022 09:25:39 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6EB0C06173B for ; Sun, 23 Jan 2022 06:25:38 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A3EF7B80CF1 for ; Sun, 23 Jan 2022 14:25:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8F97C340E2; Sun, 23 Jan 2022 14:25:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1642947936; bh=HcnH1YK1zNX8A/XJwpKHPNmhD43FxImF+aG1VhiGccE=; h=Subject:To:Cc:From:Date:From; b=Gk7C/tmT5R1lszyrU9MIYpH+Hf8Q0wL8ituvYwKUcKsEhjYM/gLVjIgYj/u3LP9h5 0LVd495H8iBfsH89x8oFCC90nmpl9KjX4prWT66x6+plUjFEFEQND3oQuOCRu2C4RJ x/dj54ysSX893Q9W1QdYP1t0mNKfM87qbu7wD93c= Subject: FAILED: patch "[PATCH] cxl/pmem: Fix module reload vs workqueue state" failed to apply to 5.15-stable tree To: dan.j.williams@intel.com, stable@vger.kernel.org, vishal.l.verma@intel.com Cc: From: Date: Sun, 23 Jan 2022 15:25:33 +0100 Message-ID: <164294793385141@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 53989fad1286e652ea3655ae3367ba698da8d2ff Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 11 Nov 2021 10:19:05 -0800 Subject: [PATCH] cxl/pmem: Fix module reload vs workqueue state A test of the form: while true; do modprobe -r cxl_pmem; modprobe cxl_pmem; done May lead to a crash signature of the form: BUG: unable to handle page fault for address: ffffffffc0660030 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page [..] Workqueue: cxl_pmem 0xffffffffc0660030 RIP: 0010:0xffffffffc0660030 Code: Unable to access opcode bytes at RIP 0xffffffffc0660006. [..] Call Trace: ? process_one_work+0x4ec/0x9c0 ? pwq_dec_nr_in_flight+0x100/0x100 ? rwlock_bug.part.0+0x60/0x60 ? worker_thread+0x2eb/0x700 In that report the 0xffffffffc0660030 address corresponds to the former function address of cxl_nvb_update_state() from a previous load of the module, not the current address. Fix that by arranging for ->state_work in the 'struct cxl_nvdimm_bridge' object to be reinitialized on cxl_pmem module reload. Details: Recall that CXL subsystem wants to link a CXL memory expander device to an NVDIMM sub-hierarchy when both a persistent memory range has been registered by the CXL platform driver (cxl_acpi) *and* when that CXL memory expander has published persistent memory capacity (Get Partition Info). To this end the cxl_nvdimm_bridge driver arranges to rescan the CXL bus when either of those conditions change. The helper bus_rescan_devices() can not be called underneath the device_lock() for any device on that bus, so the cxl_nvdimm_bridge driver uses a workqueue for the rescan. Typically a driver allocates driver data to hold a 'struct work_struct' for a driven device, but for a workqueue that may run after ->remove() returns, driver data will have been freed. The 'struct cxl_nvdimm_bridge' object holds the state and work_struct directly. Unfortunately it was only arranging for that infrastructure to be initialized once per device creation rather than the necessary once per workqueue (cxl_pmem_wq) creation. Introduce is_cxl_nvdimm_bridge() and cxl_nvdimm_bridge_reset() in support of invalidating stale references to a recently destroyed cxl_pmem_wq. Cc: Fixes: 8fdcb1704f61 ("cxl/pmem: Add initial infrastructure for pmem support") Reported-by: Vishal Verma Tested-by: Vishal Verma Link: https://lore.kernel.org/r/163665474585.3505991.8397182770066720755.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c index 2e402f0b2a10..b5fca97b0a07 100644 --- a/drivers/cxl/core/pmem.c +++ b/drivers/cxl/core/pmem.c @@ -51,10 +51,16 @@ struct cxl_nvdimm_bridge *to_cxl_nvdimm_bridge(struct device *dev) } EXPORT_SYMBOL_NS_GPL(to_cxl_nvdimm_bridge, CXL); -__mock int match_nvdimm_bridge(struct device *dev, const void *data) +bool is_cxl_nvdimm_bridge(struct device *dev) { return dev->type == &cxl_nvdimm_bridge_type; } +EXPORT_SYMBOL_NS_GPL(is_cxl_nvdimm_bridge, CXL); + +__mock int match_nvdimm_bridge(struct device *dev, const void *data) +{ + return is_cxl_nvdimm_bridge(dev); +} struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_nvdimm *cxl_nvd) { diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 3af704e9b448..ab4596f0b751 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -196,6 +196,13 @@ struct cxl_decoder { }; +/** + * enum cxl_nvdimm_brige_state - state machine for managing bus rescans + * @CXL_NVB_NEW: Set at bridge create and after cxl_pmem_wq is destroyed + * @CXL_NVB_DEAD: Set at brige unregistration to preclude async probing + * @CXL_NVB_ONLINE: Target state after successful ->probe() + * @CXL_NVB_OFFLINE: Target state after ->remove() or failed ->probe() + */ enum cxl_nvdimm_brige_state { CXL_NVB_NEW, CXL_NVB_DEAD, @@ -308,6 +315,7 @@ struct cxl_nvdimm_bridge *devm_cxl_add_nvdimm_bridge(struct device *host, struct cxl_port *port); struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev); bool is_cxl_nvdimm(struct device *dev); +bool is_cxl_nvdimm_bridge(struct device *dev); int devm_cxl_add_nvdimm(struct device *host, struct cxl_memdev *cxlmd); struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_nvdimm *cxl_nvd); diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c index 17e82ae90456..b65a272a2d6d 100644 --- a/drivers/cxl/pmem.c +++ b/drivers/cxl/pmem.c @@ -315,6 +315,31 @@ static struct cxl_driver cxl_nvdimm_bridge_driver = { .id = CXL_DEVICE_NVDIMM_BRIDGE, }; +/* + * Return all bridges to the CXL_NVB_NEW state to invalidate any + * ->state_work referring to the now destroyed cxl_pmem_wq. + */ +static int cxl_nvdimm_bridge_reset(struct device *dev, void *data) +{ + struct cxl_nvdimm_bridge *cxl_nvb; + + if (!is_cxl_nvdimm_bridge(dev)) + return 0; + + cxl_nvb = to_cxl_nvdimm_bridge(dev); + device_lock(dev); + cxl_nvb->state = CXL_NVB_NEW; + device_unlock(dev); + + return 0; +} + +static void destroy_cxl_pmem_wq(void) +{ + destroy_workqueue(cxl_pmem_wq); + bus_for_each_dev(&cxl_bus_type, NULL, NULL, cxl_nvdimm_bridge_reset); +} + static __init int cxl_pmem_init(void) { int rc; @@ -340,7 +365,7 @@ static __init int cxl_pmem_init(void) err_nvdimm: cxl_driver_unregister(&cxl_nvdimm_bridge_driver); err_bridge: - destroy_workqueue(cxl_pmem_wq); + destroy_cxl_pmem_wq(); return rc; } @@ -348,7 +373,7 @@ static __exit void cxl_pmem_exit(void) { cxl_driver_unregister(&cxl_nvdimm_driver); cxl_driver_unregister(&cxl_nvdimm_bridge_driver); - destroy_workqueue(cxl_pmem_wq); + destroy_cxl_pmem_wq(); } MODULE_LICENSE("GPL v2");