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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AECE8C433EF for ; Thu, 25 Nov 2021 03:33:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3EF6F6B0074; Wed, 24 Nov 2021 22:32:50 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 39F756B0075; Wed, 24 Nov 2021 22:32:50 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B62D6B007B; Wed, 24 Nov 2021 22:32:50 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0215.hostedemail.com [216.40.44.215]) by kanga.kvack.org (Postfix) with ESMTP id 1D5316B0074 for ; Wed, 24 Nov 2021 22:32:50 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id DBF1C1852F214 for ; Thu, 25 Nov 2021 03:32:39 +0000 (UTC) X-FDA: 78846030438.16.B8A6EEF Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf28.hostedemail.com (Postfix) with ESMTP id 80E4890000BE for ; Thu, 25 Nov 2021 03:32:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=sarg9j5uWpI80F+KYVVMFI4IuQs+6DnBhpJFGqNmqjE=; b=UyglqFLIIELXdNN5G/Cc95S9CL Pwp3FTeuSvheJxG93898eO3cgBX+B/aClH/M+VHmFsFMcYwu3lVb5LE2BhaUdRCacWY8Vm5qo7e6u +zalP0PUiLwddUZqpTDi7Tgc3nO9qRep/zSE2gu8coVo8AiA5OyxS0bFuXlC6IyC2hXsyBJTActvw +omFB3LvlO+cuyc2biu8Z0AUADJXq8PWslJy3x+GG01XFt+rraUJXRs1EY0geT49+EMMSY8B7OxVp fHY85twGQhyP13Q3I10tGt9GWc57FlNT7nxk2AWENO1h2FgeVqPTNCwfpzivR4ihAfZMs9NoJIBaG Kgmz9GCw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mq5Ut-004Zro-FL; Thu, 25 Nov 2021 03:32:31 +0000 Date: Thu, 25 Nov 2021 03:32:31 +0000 From: Matthew Wilcox To: John Hubbard Cc: Andrew Morton , cgel.zte@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chiminghao , Zeal Robot Subject: Re: [PATCH] mm: Use BUG_ON instead of if condition followed by BUG Message-ID: References: <20211124030849.34998-1-chi.minghao@zte.com.cn> <20211124142751.e48cdcc3aea9e0ef899f4347@linux-foundation.org> <348f3a1f-c7d3-c21f-419d-7acd2e5290b6@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <348f3a1f-c7d3-c21f-419d-7acd2e5290b6@nvidia.com> X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 80E4890000BE X-Stat-Signature: z16zd4oqjr6r5w6qqnw3te4dkni9aayp Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=UyglqFLI; dmarc=none; spf=none (imf28.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-HE-Tag: 1637811159-77914 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Nov 24, 2021 at 02:45:59PM -0800, John Hubbard wrote: > @@ -2201,13 +2201,12 @@ static int __ref try_remove_memory(u64 start, u64 size) > */ > void __remove_memory(u64 start, u64 size) > { > - > + int ret = try_remove_memory(start, size); > /* > * trigger BUG() if some memory is not offlined prior to calling this > * function > */ > - if (try_remove_memory(start, size)) > - BUG(); > + BUG_ON(ret); > } I'd rather leave it the way it is. I don't see why the version you propose is better. > ...and by the way, while going to type that, I immediately stumbled upon > another pre-existing case of this sort of thing, in try_remove_memory(), > which does this: > > static int __ref try_remove_memory(u64 start, u64 size) > { > struct vmem_altmap mhp_altmap = {}; > struct vmem_altmap *altmap = NULL; > unsigned long nr_vmemmap_pages; > int rc = 0, nid = NUMA_NO_NODE; > > BUG_ON(check_hotplug_memory_range(start, size)); That needs to be fixed.