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 276E7C433EF for ; Mon, 28 Feb 2022 01:39:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232324AbiB1Bjl (ORCPT ); Sun, 27 Feb 2022 20:39:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46530 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232083AbiB1Bjk (ORCPT ); Sun, 27 Feb 2022 20:39:40 -0500 Received: from nautica.notk.org (ipv6.notk.org [IPv6:2001:41d0:1:7a93::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B79E4220DD; Sun, 27 Feb 2022 17:39:01 -0800 (PST) Received: by nautica.notk.org (Postfix, from userid 108) id CD60CC021; Mon, 28 Feb 2022 02:38:55 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1646012335; bh=ppd2glzcFuscrKkv8TaEP18WFv+ORpmIkkSFkUHICKk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=soJF5RcOsYnglkImQtb9pIl/qP0khiWeql+7Q6WwujVLmRGcXKH3MDHyZJoDXkoNZ nfLwdNmR94ipRhpfU/yGGtQ0CCPAl+7FpblPZV8W/XGjkCEuWOVtaj1L3iJZNb1N2c CdFOmEkUilyqU7UyR5ey2DFe4qxL2CTrCOVK5hn01HnX0h1O+PjEcdIRgQrW8XJmxl H+hkzWGGaj+LESdwk6Ju5LgHdmiE30kl8numPoA7Ri/9ofIaiBnajtGSDvwJu4XUQA 5b720TWpoaAk8d9fQ/2jmPHL9z5lscohyyh4S3MA6L5C1XoE86p8B9XZe5Z5DVVfvD as1TbQlailyOw== Received: from odin.codewreck.org (localhost [127.0.0.1]) by nautica.notk.org (Postfix) with ESMTPS id 12DEEC009; Mon, 28 Feb 2022 02:38:51 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1646012334; bh=ppd2glzcFuscrKkv8TaEP18WFv+ORpmIkkSFkUHICKk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1PSLUt443Hf1hB90umtNGuJtN+Kh6sjXkX8fXCfBQZMFA0VTGkp2DjToqsTKDv02n bxMx5jkWll/W/NDF6NCs8nWS1/04hJh9N3rUtC8UPxDJBokFK26va6822UCXfQ9xxN TZejmVbF+paZ96VIN1n1A8vABAf9WTp8XyDdVH0Ejy9JeFmI/7lGwA8J4AfcKDsF3O Wogq7gjlWn8wiNDOYgOE9uLcnb5zNlpwVm5cNs1qNHmP9+Mv8DVxtqDl+E49qffKqP gMWaZZ+ipQvc9z3R1bgkEFr2Lp1z6fNdJFhRMv4YwFM4rRCWZF1lgGPFCUVnwZaWhD Xf4n2h+Q2d0OQ== Received: from localhost (odin.codewreck.org [local]) by odin.codewreck.org (OpenSMTPD) with ESMTPA id 9b6fd6d8; Mon, 28 Feb 2022 01:38:48 +0000 (UTC) Date: Mon, 28 Feb 2022 10:38:33 +0900 From: asmadeus@codewreck.org To: syzbot Cc: davem@davemloft.net, ericvh@gmail.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux_oss@crudebyte.com, lucho@ionkov.net, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, v9fs-developer@lists.sourceforge.net Subject: Re: [syzbot] WARNING in p9_client_destroy Message-ID: References: <00000000000011f0c905d9097a62@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <00000000000011f0c905d9097a62@google.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org syzbot wrote on Sun, Feb 27, 2022 at 04:53:29PM -0800: > kmem_cache_destroy 9p-fcall-cache: Slab cache still has objects when > called from p9_client_destroy+0x213/0x370 net/9p/client.c:1100 hmm, there is no previous "Packet with tag %d has still references" (sic) message, so this is probably because p9_tag_cleanup only relies on rcu read lock for consistency, so even if the connection has been closed above (clnt->trans_mode->close) there could have been a request sent (= tag added) just before that which isn't visible on the destroying side? I guess adding an rcu_barrier() is what makes most sense here to protect this case? I'll send a patch in the next few days unless it was a stupid idea. -- Dominique