From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
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 EA673C77B7F
	for <linux-mm@archiver.kernel.org>; Wed,  3 May 2023 15:49:40 +0000 (UTC)
Received: by kanga.kvack.org (Postfix)
	id 495BB6B0083; Wed,  3 May 2023 11:49:40 -0400 (EDT)
Received: by kanga.kvack.org (Postfix, from userid 40)
	id 41C896B0085; Wed,  3 May 2023 11:49:40 -0400 (EDT)
X-Delivered-To: int-list-linux-mm@kvack.org
Received: by kanga.kvack.org (Postfix, from userid 63042)
	id 331116B0087; Wed,  3 May 2023 11:49:40 -0400 (EDT)
X-Delivered-To: linux-mm@kvack.org
Received: from verein.lst.de (verein.lst.de [213.95.11.211])
	by kanga.kvack.org (Postfix) with ESMTP id 0D9136B0083
	for <linux-mm@kvack.org>; Wed,  3 May 2023 11:49:40 -0400 (EDT)
Received: by verein.lst.de (Postfix, from userid 2407)
	id 30FC668AA6; Wed,  3 May 2023 17:49:36 +0200 (CEST)
Date: Wed, 3 May 2023 17:49:36 +0200
From: Christoph Hellwig <hch@lst.de>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>, akpm@linux-foundation.org, jack@suse.cz,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	dhowells@redhat.com, marc.dionne@auristor.com,
	linux-afs@lists.infradead.org,
	syzbot+48011b86c8ea329af1b9@syzkaller.appspotmail.com
Subject: Re: [PATCH 1/2] filemap: fix the conditional folio_put in
 filemap_fault
Message-ID: <20230503154936.GA31522@lst.de>
References: <20230503154526.1223095-1-hch@lst.de> <ZFKCRPRgoKWaWhQW@casper.infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <ZFKCRPRgoKWaWhQW@casper.infradead.org>
User-Agent: Mutt/1.5.17 (2007-11-01)
X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4
Sender: owner-linux-mm@kvack.org
Precedence: bulk
X-Loop: owner-majordomo@kvack.org
List-ID: <linux-mm.kvack.org>

On Wed, May 03, 2023 at 04:48:20PM +0100, Matthew Wilcox wrote:
> > -		folio_put(folio);
> 
> Why not simply:
> 
> -	if (folio)
> +	if (!IS_ERR_OR_NULL(folio))

no need for the OR_NULL.  But I find the extra label way easier to
reason about, and it's exactly the same amount of code.