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=-17.6 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,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 D447EC433DB for ; Mon, 1 Feb 2021 17:55:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F00264E92 for ; Mon, 1 Feb 2021 17:55:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232607AbhBARzj (ORCPT ); Mon, 1 Feb 2021 12:55:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:27643 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229534AbhBARz0 (ORCPT ); Mon, 1 Feb 2021 12:55:26 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612202040; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TItgm0+VXZQkzT+vjmzxyshp9Ksb9PzGNBOZr7Z/D5g=; b=AgS0U4cct9/YXvNWb2z6PzrYAR3qpLPorf5rVA0uSc5zWf5GCzH/Es/KUowmtpi618qdM5 5eCPhwjME6015WyRS407iRlun21RRSDNTC4VSzdrh61xlxs9/6BAjjhtCtpB2pud/tPqp5 4opV88nhPKA8JapeXh9cikaxGNd135g= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-519-TVApnOdZMD-FJdEy0ErIwg-1; Mon, 01 Feb 2021 12:53:57 -0500 X-MC-Unique: TVApnOdZMD-FJdEy0ErIwg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CAEE259; Mon, 1 Feb 2021 17:53:55 +0000 (UTC) Received: from llong.remote.csb (ovpn-118-89.rdu2.redhat.com [10.10.118.89]) by smtp.corp.redhat.com (Postfix) with ESMTP id 000A419716; Mon, 1 Feb 2021 17:53:53 +0000 (UTC) Subject: Re: corrupted pvqspinlock in htab_map_update_elem To: Peter Zijlstra , Dmitry Vyukov Cc: Alexei Starovoitov , Daniel Borkmann , andrii@kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , kpsingh@kernel.org, netdev , bpf , LKML , Ingo Molnar References: From: Waiman Long Organization: Red Hat Message-ID: <5936f4a4-f150-e56e-f07d-1efee06eba16@redhat.com> Date: Mon, 1 Feb 2021 12:53:53 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/1/21 6:23 AM, Peter Zijlstra wrote: > On Mon, Feb 01, 2021 at 10:50:58AM +0100, Peter Zijlstra wrote: > >>> queued_spin_unlock arch/x86/include/asm/qspinlock.h:56 [inline] >>> lockdep_unlock+0x10e/0x290 kernel/locking/lockdep.c:124 >>> debug_locks_off_graph_unlock kernel/locking/lockdep.c:165 [inline] >>> print_usage_bug kernel/locking/lockdep.c:3710 [inline] >> Ha, I think you hit a bug in lockdep. > Something like so I suppose. > > --- > Subject: locking/lockdep: Avoid unmatched unlock > From: Peter Zijlstra > Date: Mon Feb 1 11:55:38 CET 2021 > > Commit f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" > inversions") overlooked that print_usage_bug() releases the graph_lock > and called it without the graph lock held. > > Fixes: f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions") > Reported-by: Dmitry Vyukov > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/locking/lockdep.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -3773,7 +3773,7 @@ static void > print_usage_bug(struct task_struct *curr, struct held_lock *this, > enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) > { > - if (!debug_locks_off_graph_unlock() || debug_locks_silent) > + if (!debug_locks_off() || debug_locks_silent) > return; > > pr_warn("\n"); > @@ -3814,6 +3814,7 @@ valid_state(struct task_struct *curr, st > enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) > { > if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) { > + graph_unlock() > print_usage_bug(curr, this, bad_bit, new_bit); > return 0; > } I have also suspected doing unlock without a corresponding lock. This patch looks good to me. Acked-by: Waiman Long Cheers, Longman