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 BE124C433FE for ; Mon, 3 Oct 2022 14:46:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229963AbiJCOqK (ORCPT ); Mon, 3 Oct 2022 10:46:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229611AbiJCOqH (ORCPT ); Mon, 3 Oct 2022 10:46:07 -0400 Received: from mta-01.yadro.com (mta-02.yadro.com [89.207.88.252]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E785A2CC99; Mon, 3 Oct 2022 07:46:02 -0700 (PDT) Received: from localhost (unknown [127.0.0.1]) by mta-01.yadro.com (Postfix) with ESMTP id 4F8B04014D; Mon, 3 Oct 2022 14:46:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=yadro.com; h= in-reply-to:content-disposition:content-type:content-type :mime-version:references:message-id:subject:subject:from:from :date:date:received:received:received:received; s=mta-01; t= 1664808359; x=1666622760; bh=f28REBdwbZdrdcPTca7rbkrfq1ht6ZdCGpO 41DAmRLg=; b=WqGHMYAcBuNTCREijAVP30718Csy1K1QNSUk9P8n1tXHIHqDxvY w66U9G8G+RbOhbmplOXnRdVHGgBEqJuu89RkSPYIV9GOrJakE94LPx38hdCh8nsN PWQLvtuhZenm3E557Ig9bqGkPpLp4RXiHbhRWFz/XMKI8DCbe0qsoFkM= X-Virus-Scanned: amavisd-new at yadro.com Received: from mta-01.yadro.com ([127.0.0.1]) by localhost (mta-01.yadro.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id IgLBIl9YdqaE; Mon, 3 Oct 2022 17:45:59 +0300 (MSK) Received: from T-EXCH-02.corp.yadro.com (T-EXCH-02.corp.yadro.com [172.17.10.102]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mta-01.yadro.com (Postfix) with ESMTPS id 714CE400F6; Mon, 3 Oct 2022 17:45:55 +0300 (MSK) Received: from T-EXCH-08.corp.yadro.com (172.17.11.58) by T-EXCH-02.corp.yadro.com (172.17.10.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384) id 15.1.669.32; Mon, 3 Oct 2022 17:45:55 +0300 Received: from yadro.com (10.199.18.20) by T-EXCH-08.corp.yadro.com (172.17.11.58) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.1118.9; Mon, 3 Oct 2022 17:45:55 +0300 Date: Mon, 3 Oct 2022 17:46:02 +0300 From: Dmitry Bogdanov To: Duoming Zhou CC: , , , , , , , Subject: Re: [PATCH] scsi: target: iscsi: cxgbit: fix sleep-in-atomic-context bug in cxgbit_abort_conn Message-ID: <20221003144602.GA10901@yadro.com> References: <20221002014047.23066-1-duoming@zju.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20221002014047.23066-1-duoming@zju.edu.cn> X-Originating-IP: [10.199.18.20] X-ClientProxiedBy: T-EXCH-01.corp.yadro.com (172.17.10.101) To T-EXCH-08.corp.yadro.com (172.17.11.58) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 02, 2022 at 09:40:47AM +0800, Duoming Zhou wrote: > > The function iscsit_handle_time2retain_timeout() is a timer handler that > runs in an atomic context, but it calls "alloc_skb(0, GFP_KERNEL | ...)" > that may sleep. As a result, the sleep-in-atomic-context bug will happen. > The process is shown below: > > iscsit_handle_time2retain_timeout() > iscsit_close_session() > iscsit_free_connection_recovery_entries() > iscsit_free_cmd() > __iscsit_free_cmd() > cxgbit_unmap_cmd() > cxgbit_abort_conn() > alloc_skb(0, GFP_KERNEL | ...) //may sleep > > This patch changes the gfp_t parameter of alloc_skb() from GFP_KERNEL to > GFP_ATOMIC in order to mitigate the bug. > > Fixes: 1ae01724ae92 ("cxgbit: Abort the TCP connection in case of data out timeout") > Signed-off-by: Duoming Zhou > --- > drivers/target/iscsi/cxgbit/cxgbit_cm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/target/iscsi/cxgbit/cxgbit_cm.c b/drivers/target/iscsi/cxgbit/cxgbit_cm.c > index 3336d2b78bf..eb3da6d2c62 100644 > --- a/drivers/target/iscsi/cxgbit/cxgbit_cm.c > +++ b/drivers/target/iscsi/cxgbit/cxgbit_cm.c > @@ -697,7 +697,7 @@ __cxgbit_abort_conn(struct cxgbit_sock *csk, struct sk_buff *skb) > > void cxgbit_abort_conn(struct cxgbit_sock *csk) > { > - struct sk_buff *skb = alloc_skb(0, GFP_KERNEL | __GFP_NOFAIL); > + struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC | __GFP_NOFAIL); > > cxgbit_get_csk(csk); > cxgbit_init_wr_wait(&csk->com.wr_wait); > -- > 2.17.1 > The last line in cxgbit_abort_conn is cxgbit_wait_for_reply() which also should not be called in interrupt context. Anyway this issue is not due to cxgbit, it is common for iSCSI itself: iscsit_close_session() iscsit_free_connection_recovery_entries() iscsit_free_cmd() transport_generic_free_cmd() target_wait_free_cmd() wait_for_completion_timeout() IMHO, there is no reason to call iscsit_close_session in an atomic context. I have two patches relaited Time2Retain timer. I will share them today. BR, Dmitry