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 C2974C43334 for ; Tue, 7 Jun 2022 11:05:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235810AbiFGLFP (ORCPT ); Tue, 7 Jun 2022 07:05:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242235AbiFGLBh (ORCPT ); Tue, 7 Jun 2022 07:01:37 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECCB4B482 for ; Tue, 7 Jun 2022 04:01:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 18CAE6156A for ; Tue, 7 Jun 2022 11:01:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7ED93C34115; Tue, 7 Jun 2022 11:01:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654599693; bh=D+6gnkjQuTp/gT1kk2TY3BFGoRR4S4mcAsiWxpLdG2g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=yu2gyUxFwJrx6gWlqtUlxYiXkJg+NrVJ5zSq4Xm5uTof1R1kd2bPRaVoCJa0iS95B i1ef7reb9rxUO/WVQV+9LfSU9SosySoVqH6YtD+sWJo8nTq0DpdglQtRPGFrsZUIOZ zSFUFjASwBNzTBV+Mm4lc6Qy2xgYx++l+AckcEJ4= Date: Tue, 7 Jun 2022 13:01:26 +0200 From: Greg KH To: duoming@zju.edu.cn Cc: linux-staging@lists.linux.dev, davem@davemloft.net, kuba@kernel.org, alexander.deucher@amd.com, broonie@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] staging: rtl8192u: Fix sleep in atomic context bug in dm_fsync_timer_callback Message-ID: References: <20220520061541.14785-1-duoming@zju.edu.cn> <6c014f68.52c9b.18137daddd9.Coremail.duoming@zju.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6c014f68.52c9b.18137daddd9.Coremail.duoming@zju.edu.cn> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 06, 2022 at 03:11:39PM +0800, duoming@zju.edu.cn wrote: > Hello, > > On Mon, 6 Jun 2022 07:43:11 +0200 greg k-h wrote: > > > On Fri, May 20, 2022 at 02:15:41PM +0800, Duoming Zhou wrote: > > > There are sleep in atomic context bugs when dm_fsync_timer_callback is > > > executing. The root cause is that the memory allocation functions with > > > GFP_KERNEL parameter are called in dm_fsync_timer_callback which is a > > > timer handler. The call paths that could trigger bugs are shown below: > > > > > > (interrupt context) > > > dm_fsync_timer_callback > > > write_nic_byte > > > kzalloc(sizeof(data), GFP_KERNEL); //may sleep > > > write_nic_dword > > > kzalloc(sizeof(data), GFP_KERNEL); //may sleep > > > > > > This patch changes allocation mode from GFP_KERNEL to GFP_ATOMIC > > > in order to prevent atomic context sleeping. The GFP_ATOMIC flag > > > makes memory allocation operation could be used in atomic context. > > > > > > Signed-off-by: Duoming Zhou > > > > What commit id does this fix? > > Thanks for your time and reply! > The commit id this patch fix is 8fc8598e61f6 ("Staging: Added Realtek rtl8192u driver to staging"). > > > And how did you find this issue? Did you run the code to verify it > > still works properly? > > I find this issue by writing codeql query. I am trying to use usb raw-gadget to simulate > rtl8192u card in order to test this code. > > What`s more, I found the usb_control_msg() with GFP_NOIO parameter in write_nic_byte() > and write_nic_dword() may also sleep. So I think use the delayed queue to replace timer > is better. Please explain all of this in the changelog text when you resend this. thanks, greg k-h