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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 654A1C433ED for ; Mon, 17 May 2021 14:17:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BF9361401 for ; Mon, 17 May 2021 14:17:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237258AbhEQOSw (ORCPT ); Mon, 17 May 2021 10:18:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:46476 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238861AbhEQOQo (ORCPT ); Mon, 17 May 2021 10:16:44 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 95686613F5; Mon, 17 May 2021 14:09:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621260577; bh=vkhSz1ZTKlNOYzE0WNy3Upzc4zgTQBrymtxywf8XbVA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NzAc+0031mCkqZMkHcaMVB7cVk2whrTb4qChJL+KzRaddQdzp5G/qqssx1+jLZMdF zUfQJcT+xDgc16OIUk3DWurDc2gUdvzbJyJSFhUNjy/juDcFmt5I7ypYk0Qpz9HSoV 9USB7MYX5cYN0jNC/jQE8O5P74OhU/6VRofrvMCs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexey Kardashevskiy , Michael Ellerman , Sasha Levin Subject: [PATCH 5.12 110/363] powerpc/iommu: Annotate nested lock for lockdep Date: Mon, 17 May 2021 15:59:36 +0200 Message-Id: <20210517140306.333521991@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210517140302.508966430@linuxfoundation.org> References: <20210517140302.508966430@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexey Kardashevskiy [ Upstream commit cc7130bf119add37f36238343a593b71ef6ecc1e ] The IOMMU table is divided into pools for concurrent mappings and each pool has a separate spinlock. When taking the ownership of an IOMMU group to pass through a device to a VM, we lock these spinlocks which triggers a false negative warning in lockdep (below). This fixes it by annotating the large pool's spinlock as a nest lock which makes lockdep not complaining when locking nested locks if the nest lock is locked already. === WARNING: possible recursive locking detected 5.11.0-le_syzkaller_a+fstn1 #100 Not tainted -------------------------------------------- qemu-system-ppc/4129 is trying to acquire lock: c0000000119bddb0 (&(p->lock)/1){....}-{2:2}, at: iommu_take_ownership+0xac/0x1e0 but task is already holding lock: c0000000119bdd30 (&(p->lock)/1){....}-{2:2}, at: iommu_take_ownership+0xac/0x1e0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(p->lock)/1); lock(&(p->lock)/1); === Signed-off-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210301063653.51003-1-aik@ozlabs.ru Signed-off-by: Sasha Levin --- arch/powerpc/kernel/iommu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index c00214a4355c..4023f91defa6 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -1096,7 +1096,7 @@ int iommu_take_ownership(struct iommu_table *tbl) spin_lock_irqsave(&tbl->large_pool.lock, flags); for (i = 0; i < tbl->nr_pools; i++) - spin_lock(&tbl->pools[i].lock); + spin_lock_nest_lock(&tbl->pools[i].lock, &tbl->large_pool.lock); iommu_table_release_pages(tbl); @@ -1124,7 +1124,7 @@ void iommu_release_ownership(struct iommu_table *tbl) spin_lock_irqsave(&tbl->large_pool.lock, flags); for (i = 0; i < tbl->nr_pools; i++) - spin_lock(&tbl->pools[i].lock); + spin_lock_nest_lock(&tbl->pools[i].lock, &tbl->large_pool.lock); memset(tbl->it_map, 0, sz); -- 2.30.2