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 3827FC678DB for ; Wed, 15 Feb 2023 20:48:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230078AbjBOUsT (ORCPT ); Wed, 15 Feb 2023 15:48:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33800 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230027AbjBOUrj (ORCPT ); Wed, 15 Feb 2023 15:47:39 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 662A94391B; Wed, 15 Feb 2023 12:46:55 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 442C361DA6; Wed, 15 Feb 2023 20:46:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51F95C433A1; Wed, 15 Feb 2023 20:46:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676494014; bh=byYUexaPJPAmBnEC6Lt4VbHe7WyASuTrTCvR4mx5I34=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HxtvC9j8Z+zp62T3FYPuIxoFasLbi3oIPBTYHDn3MV/SfhjDb4HgAf1Ts9cEIEbmb Hm0ymL6RnA29NLxWkpxJKGnTISvRBt0Fq/oiwpboB6zsBYypGeUUByDNB50wiASFZh pEpckdkKlLMDT8sNDAf4nqUS6jTs5dV2BcNR+iW1cilvPlcOCe5fx4Ri9u4zAr2sIC /KMYehfyRcBlt3R7pQnsxrlRuaDW5PBCGzMCg1k/h6qlYBun8XfNwo2Esp4Mkdbyr2 w9xSaO8gP5RbZ8LqFUxZYacxnpAr+GJ5scC029C/k1dOCeaZ5/Pl/RTVh6Pq1/R0F+ 0u7VwFPpKeI2Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vishal Verma , Dan Williams , Sasha Levin , dave.jiang@intel.com, ira.weiny@intel.com, rafael@kernel.org, nvdimm@lists.linux.dev, linux-acpi@vger.kernel.org Subject: [PATCH AUTOSEL 5.10 4/8] ACPI: NFIT: fix a potential deadlock during NFIT teardown Date: Wed, 15 Feb 2023 15:46:45 -0500 Message-Id: <20230215204649.2761225-4-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230215204649.2761225-1-sashal@kernel.org> References: <20230215204649.2761225-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vishal Verma [ Upstream commit fb6df4366f86dd252bfa3049edffa52d17e7b895 ] Lockdep reports that acpi_nfit_shutdown() may deadlock against an opportune acpi_nfit_scrub(). acpi_nfit_scrub () is run from inside a 'work' and therefore has already acquired workqueue-internal locks. It also acquiires acpi_desc->init_mutex. acpi_nfit_shutdown() first acquires init_mutex, and was subsequently attempting to cancel any pending workqueue items. This reversed locking order causes a potential deadlock: ====================================================== WARNING: possible circular locking dependency detected 6.2.0-rc3 #116 Tainted: G O N ------------------------------------------------------ libndctl/1958 is trying to acquire lock: ffff888129b461c0 ((work_completion)(&(&acpi_desc->dwork)->work)){+.+.}-{0:0}, at: __flush_work+0x43/0x450 but task is already holding lock: ffff888129b460e8 (&acpi_desc->init_mutex){+.+.}-{3:3}, at: acpi_nfit_shutdown+0x87/0xd0 [nfit] which lock already depends on the new lock. ... Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&acpi_desc->init_mutex); lock((work_completion)(&(&acpi_desc->dwork)->work)); lock(&acpi_desc->init_mutex); lock((work_completion)(&(&acpi_desc->dwork)->work)); *** DEADLOCK *** Since the workqueue manipulation is protected by its own internal locking, the cancellation of pending work doesn't need to be done under acpi_desc->init_mutex. Move cancel_delayed_work_sync() outside the init_mutex to fix the deadlock. Any work that starts after acpi_nfit_shutdown() drops the lock will see ARS_CANCEL, and the cancel_delayed_work_sync() will safely flush it out. Reported-by: Dan Williams Signed-off-by: Vishal Verma Link: https://lore.kernel.org/r/20230112-acpi_nfit_lockdep-v1-1-660be4dd10be@intel.com Signed-off-by: Dan Williams Signed-off-by: Sasha Levin --- drivers/acpi/nfit/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c index 99e23a5df0267..2306abb09f7f5 100644 --- a/drivers/acpi/nfit/core.c +++ b/drivers/acpi/nfit/core.c @@ -3687,8 +3687,8 @@ void acpi_nfit_shutdown(void *data) mutex_lock(&acpi_desc->init_mutex); set_bit(ARS_CANCEL, &acpi_desc->scrub_flags); - cancel_delayed_work_sync(&acpi_desc->dwork); mutex_unlock(&acpi_desc->init_mutex); + cancel_delayed_work_sync(&acpi_desc->dwork); /* * Bounce the nvdimm bus lock to make sure any in-flight -- 2.39.0