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 A4A88C433FE for ; Mon, 10 Oct 2022 03:46:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F31F66B0071; Sun, 9 Oct 2022 23:46:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EE1ED6B0073; Sun, 9 Oct 2022 23:46:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DD0736B0074; Sun, 9 Oct 2022 23:46:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id CA8036B0071 for ; Sun, 9 Oct 2022 23:46:23 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 93199A0A7D for ; Mon, 10 Oct 2022 03:46:23 +0000 (UTC) X-FDA: 80003652246.21.3B9466A Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf02.hostedemail.com (Postfix) with ESMTP id 5F3B98000F for ; Mon, 10 Oct 2022 03:46:22 +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=0RvipzyCwcwCdOuCNQFfFNwYNR5sm1Uw9mApVKX+WO8=; b=MZdqDSH4EfjD25C0qM1EJoYWQM lv2CiLKsO1p4L6g73V9Y45cuO3XMDkMQb5yD411PSkYm3rrEYCHwVI8BoOSw2fXSTnMcmbt/hv2oS rAsAxj3Kjjwk7JQCsAvQIA0G4FfdEkcJ9rqGqhJwRQXxzKFAWGuaKWCkN+V/+ptngFjKKBvfZVr3h 2TF9u1g1h0xLA6UgYv1XEXhlA7kJKFSCL5yMOdEpaLOMMNfuediK/e0n+pglh0s6y5aNOiUiIuYTZ YU2bO10QT5yW9X4nS/JpXZt5DA72ZYA6X1ThO7RVvIgbk6nJPu/SSfUQ0ttovkPHt3apbVYCWwP5J kvSkcnzA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1ohjkE-003v8q-5p; Mon, 10 Oct 2022 03:46:22 +0000 Date: Mon, 10 Oct 2022 04:46:22 +0100 From: Matthew Wilcox To: XU pengfei Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2] mm/mmap_lock: Remove unnecessary 'NULL' values from Pointer Message-ID: References: <20221010034238.3604-1-xupengfei@nfschina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221010034238.3604-1-xupengfei@nfschina.com> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665373583; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0RvipzyCwcwCdOuCNQFfFNwYNR5sm1Uw9mApVKX+WO8=; b=tptp5ZwdCA47/Gpuj/d1JMOoOtzOODPLIOLG7uCKOxb8zeITG6gjOvulNodrtRuba47Hdb nbMTOHPXWQMOrhT/7FL54SjvPyxyOc2aNRaoOaCGdyWRgAbTXddHnN5gRtHX+XU2erVw4B 8/B73By044oWMuG3Wek8hpJdUO36QmY= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=MZdqDSH4; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665373583; a=rsa-sha256; cv=none; b=bD9xJW42EPIRoL1iPM0f7tftyKC8Wv+H3G+VVDbuvqX5NtkFvXxVnSWKVqaJKtY3tJ/akd UICA5BWUHw/W+LS13JzThlJy6C5+H4PEFKj72y527aT6jTZ3FMAQfmEgkYaPHFQWCNJp0E z75kg0Nn9UDAtRXNdll+G8aqUSJYy6w= Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=MZdqDSH4; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspam-User: X-Stat-Signature: an1ooq6woisn8yor3xwzme89uyr3wpcm X-Rspamd-Queue-Id: 5F3B98000F X-Rspamd-Server: rspam01 X-HE-Tag: 1665373582-212013 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: On Mon, Oct 10, 2022 at 11:42:38AM +0800, XU pengfei wrote: > Pointer variables allocate memory first, and then judge. There is no > need to initialize the assignment. This seems worse to me.