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 AD999C07E9D for ; Mon, 26 Sep 2022 06:44:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233578AbiIZGoj (ORCPT ); Mon, 26 Sep 2022 02:44:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230169AbiIZGof (ORCPT ); Mon, 26 Sep 2022 02:44:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4B562FB for ; Sun, 25 Sep 2022 23:44:31 -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 4A99960ABA for ; Mon, 26 Sep 2022 06:44:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59D78C433D6; Mon, 26 Sep 2022 06:44:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1664174670; bh=Qw/WUCw4zPmr8hfqOYYDyEiNaTMxoMtF2IxYIaV1Lqo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=X3+6kv4iRcMKlUWjgfsYVxrcJznUCrUlOOVCHNFI45hW/YjtgiFTJPnjgYjYDjbjJ ojsK8E9kU2dyet5wlQFuW+M9l4EPzFkEKsPJV2OsaqHTvTG65Z8FzyG++udOUPINXz qot2hednsLt8ywwauuEjvPLe5xfO0LtDsypTTuV4= Date: Mon, 26 Sep 2022 08:44:28 +0200 From: Greg KH To: duoming@zju.edu.cn Cc: johannes@sipsolutions.net, linux-kernel@vger.kernel.org, rafael@kernel.org Subject: Re: [PATCH V9] devcoredump: add context check in dev_coredumpm Message-ID: References: <20220926061609.44153-1-duoming@zju.edu.cn> <66a140d1.f7b7e.1837884be23.Coremail.duoming@zju.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <66a140d1.f7b7e.1837884be23.Coremail.duoming@zju.edu.cn> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 26, 2022 at 02:38:28PM +0800, duoming@zju.edu.cn wrote: > Hello, > > On Mon, 26 Sep 2022 08:27:58 +0200 Greg KH wrote: > > > On Mon, Sep 26, 2022 at 02:16:09PM +0800, Duoming Zhou wrote: > > > The dev_coredumpm(), dev_coredumpv() and dev_coredumpsg() could not > > > be used in atomic context, because they call kvasprintf_const() and > > > kstrdup() with GFP_KERNEL parameter. The process is shown below: > > > > > > dev_coredumpv(.., gfp_t gfp) > > > dev_coredumpm(.., gfp_t gfp) > > > dev_set_name > > > kobject_set_name_vargs > > > kvasprintf_const(GFP_KERNEL, ...); //may sleep > > > kstrdup(s, GFP_KERNEL); //may sleep > > > > > > This patch adds context check in dev_coredumpm() in order to show > > > dev_coredumpm() and its callers could not be used in atomic context. > > > > > > What's more, this change can allow the api to evolve and will not > > > influence the users that call this api. > > > > > > Fixes: 833c95456a70 ("device coredump: add new device coredump class") > > > Signed-off-by: Duoming Zhou > > > --- > > > Changes in v9: > > > - Add context check in dev_coredumpm(). > > > > > > drivers/base/devcoredump.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c > > > index f4d794d6bb8..806ee872f5f 100644 > > > --- a/drivers/base/devcoredump.c > > > +++ b/drivers/base/devcoredump.c > > > @@ -255,6 +255,9 @@ void dev_coredumpm(struct device *dev, struct module *owner, > > > struct devcd_entry *devcd; > > > struct device *existing; > > > > > > + if (!gfpflags_normal_context(gfp)) > > > + goto free; > > > > Wait, this just broke things for no good reason if a caller happened to > > have set a GFP flag that we do not like at the moment. > > > > What code now does not work that previously did work with this change? > > I found that all users in the kernel call the dev_coredumpv(), dev_coredumpm() and > dev_coredumpsg() with "GFP_KERNEL". So this change will not influence the existing users. Great, so there is no need for this, and it does not "fix" any commit. confused, greg k-h