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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS autolearn=no 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 30181C47082 for ; Wed, 26 May 2021 20:43:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A97A4613D2 for ; Wed, 26 May 2021 20:43:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A97A4613D2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7EFCE6B0036; Wed, 26 May 2021 16:43:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 798316B006E; Wed, 26 May 2021 16:43:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 37DCC6B0070; Wed, 26 May 2021 16:43:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0183.hostedemail.com [216.40.44.183]) by kanga.kvack.org (Postfix) with ESMTP id EC9A76B0036 for ; Wed, 26 May 2021 16:43:23 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 7A0CA181AEF32 for ; Wed, 26 May 2021 20:43:23 +0000 (UTC) X-FDA: 78184557486.24.3C0ED7F Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf14.hostedemail.com (Postfix) with ESMTP id 32CA8C0042C4 for ; Wed, 26 May 2021 20:43:15 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id DD4EA613C7; Wed, 26 May 2021 20:43:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1622061802; bh=Wc0VpiNTofyWs1k/w7vX8Lh3TnH80xRCPirGtLFyVPI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=RyuWUuz9Wqha7WDVAel0HwsYR+YjnUkiTHQ+CA3lL0pH90SXDsGQYssU3bqAAmuPf GC199lyAGoWTlfwC4P3vddNREIR+y8QrjvVuIjzWkrxwW7YbtgkT8bxAPjON4pwXWI TB1H3Y0KdYu/CHYNaF+lt3nafVuovwyPpQLIotV0= Date: Wed, 26 May 2021 13:43:21 -0700 From: Andrew Morton To: Waiman Long Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Muchun Song Subject: Re: [PATCH-next] mm/memcontrol.c: Fix potential uninitialized variable warning Message-Id: <20210526134321.42bbd4a9dcbcf53e855c5b1b@linux-foundation.org> In-Reply-To: <20210526193602.8742-1-longman@redhat.com> References: <20210526193602.8742-1-longman@redhat.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=RyuWUuz9; dmarc=none; spf=pass (imf14.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Stat-Signature: 6gxtg78ax6yarsnfa4fdzugmnoja85n8 X-Rspamd-Queue-Id: 32CA8C0042C4 X-Rspamd-Server: rspam02 X-HE-Tag: 1622061795-64634 Content-Transfer-Encoding: quoted-printable 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 Wed, 26 May 2021 15:36:02 -0400 Waiman Long wrote= : > If the -Wno-maybe-uninitialized gcc option is not specified, compilatio= n > of memcontrol.c may generate the following warnings: >=20 > mm/memcontrol.c: In function =E2=80=98refill_obj_stock=E2=80=99: > ./arch/x86/include/asm/irqflags.h:127:17: warning: =E2=80=98flags=E2=80= =99 may be used uninitialized in this function [-Wmaybe-uninitialized] > return !(flags & X86_EFLAGS_IF); > ~~~~~~~^~~~~~~~~~~~~~~~ > mm/memcontrol.c:3216:16: note: =E2=80=98flags=E2=80=99 was declared her= e > unsigned long flags; > ^~~~~ > In file included from mm/memcontrol.c:29: > mm/memcontrol.c: In function =E2=80=98uncharge_page=E2=80=99: > ./include/linux/memcontrol.h:797:2: warning: =E2=80=98objcg=E2=80=99 ma= y be used uninitialized in this function [-Wmaybe-uninitialized] > percpu_ref_put(&objcg->refcnt); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >=20 > Fix that by properly initializing *pflags in get_obj_stock() and > introducing a use_objcg bool variable in uncharge_page() to avoid > potentially accessing the struct page data twice. >=20 Thanks. I'll queue this as a fix against your "mm/memcg: optimize user context object stock access".