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 F2023C4332F for ; Wed, 9 Nov 2022 15:46:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231267AbiKIPqn (ORCPT ); Wed, 9 Nov 2022 10:46:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230093AbiKIPql (ORCPT ); Wed, 9 Nov 2022 10:46:41 -0500 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B24F810FD3 for ; Wed, 9 Nov 2022 07:46:40 -0800 (PST) Received: by mail-pj1-x1033.google.com with SMTP id v4-20020a17090a088400b00212cb0ed97eso2275999pjc.5 for ; Wed, 09 Nov 2022 07:46:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=xZ2A0m4TgBzszRDy9z9vcXOFUGK9jfh5OUJcLxvh/h0=; b=LDvkCn3rxHci73vfoao/encxzaYvwC+2pzLmEgA/IFDUofNyHB8092Sen50KULTiTA dkcRHp+EhqjHTdPFRNtFLyTdeHCH/7sk/QMTMt2X8UlodrGObVqKyOnRBhibjutc20nD jsjEQCYlQtnXEWUB2HxkS9BBRVztNTIPcxD6FqAjgTUs8vc5epRGrFQR2u0XdnUtfPJm z8eRsHgHIhkztpekuFrxNpkiBpGf13PoYvNcXSGyoyfvvaoYNm4fOEdzNSW3vtM6R+Uw g90uu6XQkcCiN15cBJ+kgz/fMk7jISkFLWeNHCDlQWg7DFPZXas/BzLACOEY/HyDWy34 rYgw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=xZ2A0m4TgBzszRDy9z9vcXOFUGK9jfh5OUJcLxvh/h0=; b=hHpkDgLMsgL3doNgv8CLUOBmE+HzIVz3/hw4qTNKzsDxdInm+CS836JH72RyBsGpKf BB9gW1uNbI1N8Ez5EbTLM2VktYtCJd0PyUkNeRxdQ+XHvczjPbYec0UuQSXeNWzf3TsB nx2sSbKIHL9n2i4KO/Tg6AfTwX9w2ojweVQXPcnybmP34mVWUeSx/u676XEsaWaxuQvU YlVj0bugKagYvOfgeCONbh0fAEOL1n432FVOvt5SnnMCUUM8IwnD7hjUikArsfnT05S1 7jc3UEHcXaV3d0nPJ2tmYx4D18ZfQdag4dfavPMMqaDSjLAkdc2rP07X0M98+8ozMjiN VLOg== X-Gm-Message-State: ACrzQf2kEK2wbUWf4ooDJofTl7ZZiaeAPTsn7aLWH+Nax85kguVLEFfo ZB6N1CAqC0GxhQNoX5zYcii6Ti8p8jGvkA== X-Google-Smtp-Source: AMsMyM5I67vMBpnvc+5aW9RaOItLwDL+K5Rvx5TdNxohisuykvfikm1Y1KaH1SNTaKXf271XZhPnsw== X-Received: by 2002:a17:90a:7523:b0:213:8a69:c502 with SMTP id q32-20020a17090a752300b002138a69c502mr63282627pjk.153.1668008799945; Wed, 09 Nov 2022 07:46:39 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-a7fa-157f-969a-4cde.res6.spectrum.com. [2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id a1-20020a1709027e4100b0017f5ba1fffasm9171714pln.297.2022.11.09.07.46.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Nov 2022 07:46:39 -0800 (PST) Sender: Tejun Heo Date: Wed, 9 Nov 2022 05:46:37 -1000 From: Tejun Heo To: Chengming Zhou Cc: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, syzbot+2fdf66e68f5f882c1074@syzkaller.appspotmail.com Subject: Re: [PATCH] fs/kernfs: Fix lockdep warning in kernfs_active() Message-ID: References: <0000000000002473fd05eca7540a@google.com> <20221109120415.55759-1-zhouchengming@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221109120415.55759-1-zhouchengming@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 09, 2022 at 08:04:15PM +0800, Chengming Zhou wrote: > syzbot found a lockdep warning in kernfs_find_and_get_node_by_id(), > bisected to the commit c25491747b21 ("kernfs: Add KERNFS_REMOVING flags"), > which didn't hold kernfs_rwsem before call kernfs_active(kn). > > Since kernfs_find_and_get_node_by_id() doesn't have to get active count > of kn, only need to get a stable refcount of kn, so it should be enough > to just check kn has been KERNFS_ACTIVATED. > > Reported-by: syzbot+2fdf66e68f5f882c1074@syzkaller.appspotmail.com > Fixes: c25491747b21 ("kernfs: Add KERNFS_REMOVING flags") > Signed-off-by: Chengming Zhou Acked-by: Tejun Heo Thanks. -- tejun