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 8C349C433F5 for ; Thu, 19 May 2022 08:50:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232221AbiESIuM (ORCPT ); Thu, 19 May 2022 04:50:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50162 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230039AbiESIuH (ORCPT ); Thu, 19 May 2022 04:50:07 -0400 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 671E09C2EA; Thu, 19 May 2022 01:50:05 -0700 (PDT) Received: by mail-pf1-x434.google.com with SMTP id u15so4542082pfi.3; Thu, 19 May 2022 01:50:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id; bh=3XkJqMzIT7yz4CKyXUBxz4w4fAs7UkUmXH0W4BT/7W8=; b=n1mCNZHUe4ovgg3yfpu6pUERAgUVRG1zsB6BUoxgbNNr3Lnhg/oeXSGOndvSRtSfWD dMmX7cA0U/sFSAicvg+f4kRaY6xakDFIU/wUUSLXn8JCMdYns3xgntTT2SxyYviJQXTC a6ea3YAJ7bJWiHbz3AuLL/bX0STqTjs1n6/aXodw7QqPoVcfZmsb2VjJMhS47iJgWxBx TD7uhK3p2bSHb6NsnDC2HWpN4e/yMP4lVRddQheY32ZUhDGt0+3G6gykd+2x4W8EeBEf iXVgd8l/wfl5ZGWMYpP3sj295BejXYTJkbl0M1hjL0qtGa+Df6Tx8Fnx/8j8N1TB8Gbi 36cg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=3XkJqMzIT7yz4CKyXUBxz4w4fAs7UkUmXH0W4BT/7W8=; b=R8kz+tI88+JQzG1xmY4NtpFPq5qTFA+cvnqtaNz4DXx7OohG4bmFaROuEkHGPzmDpJ g4eUrqwbm8xyk4vzSHHYejepWPnThdiH5LSt2HkBHCRgLf13cRi8oXSibQP25wpEZ77N 1Um8gCTQQFRWr7bftUrdYDO0TXigqT6RVy8CgEV+w7/ufJd/ycyn3x12fqlGDYmI1nAk GXwpPXOqYLx9RnbnQbyt2deGEmJjbKfLPK6/pztEMeAEdSS5jpUTYn74KGO4I2UWxCso MZHYfI433nQ/1A3vaBargL83lXcjtYkP+8D14x2d1krS509inmkjpSSFDiXxKNLuZPwF OZFQ== X-Gm-Message-State: AOAM530uNWhkCN5+eH+rFrad9nZwFoUVN3o6DG+VWR+bWqLciDceZNFt rYrDADgCQW815kN/Q7co/uNDBuPLYF4= X-Google-Smtp-Source: ABdhPJzg+ucf7JA/MR7KeLOdvkun7oa5j/LfwORuKmFSUEigc9js36dXS+WdztpISTps7LqP1AFCwg== X-Received: by 2002:a05:6a00:1a89:b0:50d:fee4:cdb1 with SMTP id e9-20020a056a001a8900b0050dfee4cdb1mr3622808pfv.85.1652950204611; Thu, 19 May 2022 01:50:04 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.84]) by smtp.googlemail.com with ESMTPSA id t18-20020a1709028c9200b0015e8d4eb2b4sm3121541plo.254.2022.05.19.01.50.02 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 May 2022 01:50:04 -0700 (PDT) From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel Subject: [PATCH] KVM: eventfd: Fix false positive RCU usage warning Date: Thu, 19 May 2022 01:49:13 -0700 Message-Id: <1652950153-12489-1-git-send-email-wanpengli@tencent.com> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wanpeng Li The below is splatting when running kvm-unit-test. ============================= WARNING: suspicious RCU usage 5.18.0-rc7 #5 Tainted: G IOE ----------------------------- /home/kernel/linux/arch/x86/kvm/../../../virt/kvm/eventfd.c:80 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 4 locks held by qemu-system-x86/35124: #0: ffff9725391d80b8 (&vcpu->mutex){+.+.}-{4:4}, at: kvm_vcpu_ioctl+0x77/0x710 [kvm] #1: ffffbd25cfb2a0b8 (&kvm->srcu){....}-{0:0}, at: vcpu_enter_guest+0xdeb/0x1900 [kvm] #2: ffffbd25cfb2b920 (&kvm->irq_srcu){....}-{0:0}, at: kvm_hv_notify_acked_sint+0x79/0x1e0 [kvm] #3: ffffbd25cfb2b920 (&kvm->irq_srcu){....}-{0:0}, at: irqfd_resampler_ack+0x5/0x110 [kvm] stack backtrace: CPU: 2 PID: 35124 Comm: qemu-system-x86 Tainted: G IOE 5.18.0-rc7 #5 Call Trace: dump_stack_lvl+0x6c/0x9b irqfd_resampler_ack+0xfd/0x110 [kvm] kvm_notify_acked_gsi+0x32/0x90 [kvm] kvm_hv_notify_acked_sint+0xc5/0x1e0 [kvm] kvm_hv_set_msr_common+0xec1/0x1160 [kvm] kvm_set_msr_common+0x7c3/0xf60 [kvm] vmx_set_msr+0x394/0x1240 [kvm_intel] kvm_set_msr_ignored_check+0x86/0x200 [kvm] kvm_emulate_wrmsr+0x4f/0x1f0 [kvm] vmx_handle_exit+0x6fb/0x7e0 [kvm_intel] vcpu_enter_guest+0xe5a/0x1900 [kvm] kvm_arch_vcpu_ioctl_run+0x16e/0xac0 [kvm] kvm_vcpu_ioctl+0x279/0x710 [kvm] __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae resampler-list is traversed using srcu_read_lock() in irqfd_resampler_ack, let's fix this false positive by list_for_each_entry_srcu() instead and lockdep expression srcu_read_lock_head() be passed as the cond argument. Signed-off-by: Wanpeng Li --- virt/kvm/eventfd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 59b1dd4a549e..2a3ed401ce46 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -77,7 +77,8 @@ irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian) idx = srcu_read_lock(&kvm->irq_srcu); - list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link) + list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link, + srcu_read_lock_held(&kvm->irq_srcu)) eventfd_signal(irqfd->resamplefd, 1); srcu_read_unlock(&kvm->irq_srcu, idx); -- 2.25.1