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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01027C432C3 for ; Thu, 28 Nov 2019 09:23:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D59D2216F4 for ; Thu, 28 Nov 2019 09:23:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726092AbfK1JXK (ORCPT ); Thu, 28 Nov 2019 04:23:10 -0500 Received: from ivanoab7.miniserver.com ([37.128.132.42]:50696 "EHLO www.kot-begemot.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726722AbfK1JXK (ORCPT ); Thu, 28 Nov 2019 04:23:10 -0500 Received: from tun252.jain.kot-begemot.co.uk ([192.168.18.6] helo=jain.kot-begemot.co.uk) by www.kot-begemot.co.uk with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1iaG0s-0006JF-SP; Thu, 28 Nov 2019 09:23:03 +0000 Received: from jain.kot-begemot.co.uk ([192.168.3.3]) by jain.kot-begemot.co.uk with esmtp (Exim 4.92) (envelope-from ) id 1iaG0q-0006Ey-Ek; Thu, 28 Nov 2019 09:23:02 +0000 Subject: Re: [PATCH -next] um: vector: use GFP_ATOMIC under spin lock To: Dan Carpenter Cc: Song Liu , Daniel Borkmann , Richard Weinberger , Jeff Dike , kernel-janitors@vger.kernel.org, Alexei Starovoitov , linux-um@lists.infradead.org, Wei Yongjun , netdev@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau References: <20191128020147.191893-1-weiyongjun1@huawei.com> <20191128080641.GD1781@kadam> <5892ee7c-ff24-fb3c-6911-44e0b1d5895f@cambridgegreys.com> <20191128083735.GE1781@kadam> From: Anton Ivanov Message-ID: <69f4767b-c095-571d-92cf-343bfb17bfc0@cambridgegreys.com> Date: Thu, 28 Nov 2019 09:22:59 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191128083735.GE1781@kadam> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Clacks-Overhead: GNU Terry Pratchett Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 28/11/2019 08:37, Dan Carpenter wrote: > On Thu, Nov 28, 2019 at 08:18:30AM +0000, Anton Ivanov wrote: >> >> >> On 28/11/2019 08:06, Dan Carpenter wrote: >>> On Thu, Nov 28, 2019 at 02:01:47AM +0000, Wei Yongjun wrote: >>>> A spin lock is taken here so we should use GFP_ATOMIC. >>>> >>>> Fixes: 9807019a62dc ("um: Loadable BPF "Firmware" for vector drivers") >>>> Signed-off-by: Wei Yongjun >>>> --- >>>> arch/um/drivers/vector_kern.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c >>>> index 92617e16829e..6ff0065a271d 100644 >>>> --- a/arch/um/drivers/vector_kern.c >>>> +++ b/arch/um/drivers/vector_kern.c >>>> @@ -1402,7 +1402,7 @@ static int vector_net_load_bpf_flash(struct net_device *dev, >>>> kfree(vp->bpf->filter); >>>> vp->bpf->filter = NULL; >>>> } else { >>>> - vp->bpf = kmalloc(sizeof(struct sock_fprog), GFP_KERNEL); >>>> + vp->bpf = kmalloc(sizeof(struct sock_fprog), GFP_ATOMIC); >>>> if (vp->bpf == NULL) { >>>> netdev_err(dev, "failed to allocate memory for firmware\n"); >>>> goto flash_fail; >>>> @@ -1414,7 +1414,7 @@ static int vector_net_load_bpf_flash(struct net_device *dev, >>>> if (request_firmware(&fw, efl->data, &vdevice->pdev.dev)) >>> ^^^^^^^^^^^^^^^^ >>> >>> Is it really possible to call request_firmware() while holding a >>> spin_lock? I was so sure that read from the disk. >> >> Works, I tested the patch quite a few times. >> > > Do you have CONFIG_DEBUG_ATOMIC_SLEEP enabled? The GFP_KERNEL calls > should have triggered a warning if so. I do not think we can use that in um. config DEBUG_ATOMIC_SLEEP bool "Sleep inside atomic section checking" select PREEMPT_COUNT depends on DEBUG_KERNEL depends on !ARCH_NO_PREEMPT In arch/um/Kconfig select ARCH_NO_PREEMPT Brgds, > > regards, > dan carpenter > > > _______________________________________________ > linux-um mailing list > linux-um@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-um > -- Anton R. Ivanov Cambridgegreys Limited. Registered in England. Company Number 10273661 https://www.cambridgegreys.com/