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 90F6EC4321E for ; Mon, 5 Dec 2022 02:25:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231269AbiLECZ1 (ORCPT ); Sun, 4 Dec 2022 21:25:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231166AbiLECZZ (ORCPT ); Sun, 4 Dec 2022 21:25:25 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5420DE0BF for ; Sun, 4 Dec 2022 18:24:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670207068; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=fIaB1bH370BEUQX73UCqoL58l3sUZhXEOj98H8aVE+Y=; b=KHF94X3AzibM7seeFV0U5qs1T+FjZbo/2xeeSQ13Sh17nYouWM0JK6qDRvWjuew+L3Pz+F 70kSkCnWBMaCMeqtY2VYOoqGI5IFHfz6WRsumPqckYjVzO/hLakjRumzOGaGbOC3T03QkN iALpU/US9f3aQgxEZSnbEhHxbLuJb6Y= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-489-xWZIlQsxOoGY0rCuJwFsRQ-1; Sun, 04 Dec 2022 21:24:25 -0500 X-MC-Unique: xWZIlQsxOoGY0rCuJwFsRQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8B56E85A59D; Mon, 5 Dec 2022 02:24:24 +0000 (UTC) Received: from localhost (ovpn-12-86.pek2.redhat.com [10.72.12.86]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B502A1759E; Mon, 5 Dec 2022 02:24:23 +0000 (UTC) Date: Mon, 5 Dec 2022 10:24:20 +0800 From: Baoquan He To: Dennis Zhou Cc: Wupeng Ma , akpm@linux-foundation.org, tj@kernel.org, cl@linux.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -next 1/1] percpu: cleanup invalid assignment to err in pcpu_alloc Message-ID: References: <20221204031430.662169-1-mawupeng1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/04/22 at 04:30pm, Dennis Zhou wrote: > Hi Baoquan and Wupeng, > > On Sun, Dec 04, 2022 at 08:11:23PM +0800, Baoquan He wrote: > > On 12/04/22 at 11:14am, Wupeng Ma wrote: > > > From: Ma Wupeng > > > > > > Assignment to err if is_atomic is true will never be used since warn > > > message can only be shown if is_atomic is false after label fail. So drop > > > it. > > > > > > Signed-off-by: Ma Wupeng > > > --- > > > mm/percpu.c | 4 +--- > > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > > > diff --git a/mm/percpu.c b/mm/percpu.c > > > index acd78da0493b..df86d79325b2 100644 > > > --- a/mm/percpu.c > > > +++ b/mm/percpu.c > > > @@ -1817,10 +1817,8 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved, > > > > > > spin_unlock_irqrestore(&pcpu_lock, flags); > > > > > > - if (is_atomic) { > > > - err = "atomic alloc failed, no space left"; > > > + if (is_atomic) > > > goto fail; > > > - } > > > > This is good catch. But I think Dennis may not like this way because he > > added the message intentionally in commit 11df02bf9bc1 ("percpu: resolve > > err may not be initialized in pcpu_alloc"). > > > > You're right Baoquan haha. I agree with Christoph as well we should > surface atomic. > > Though I don't think below is quite right either. We should likely have > a separate warn_limit for atomic and I need to think about dump_stack() > if there are any requirements there. Yeah, sounds reasonable. I didn't think it over. > > > > Can we change the conditional checking in fail part as below? > > > > diff --git a/mm/percpu.c b/mm/percpu.c > > index 27697b2429c2..0ac55500fad9 100644 > > --- a/mm/percpu.c > > +++ b/mm/percpu.c > > @@ -1897,7 +1897,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved, > > fail: > > trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align); > > > > - if (!is_atomic && do_warn && warn_limit) { > > + if (do_warn && warn_limit) { > > pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n", > > size, align, is_atomic, err); > > dump_stack(); > > >