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 EFCA0C433FE for ; Wed, 26 Jan 2022 21:38:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4EBEC6B0071; Wed, 26 Jan 2022 16:38:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 473AF6B0072; Wed, 26 Jan 2022 16:38:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 314266B0073; Wed, 26 Jan 2022 16:38:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0092.hostedemail.com [216.40.44.92]) by kanga.kvack.org (Postfix) with ESMTP id 1B8F06B0071 for ; Wed, 26 Jan 2022 16:38:45 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id D87A98DC1E for ; Wed, 26 Jan 2022 21:38:44 +0000 (UTC) X-FDA: 79073752968.18.FA38AA7 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf14.hostedemail.com (Postfix) with ESMTP id 64CBA10000C for ; Wed, 26 Jan 2022 21:38:44 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id F1075B81EA5; Wed, 26 Jan 2022 21:38:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8D55C340E3; Wed, 26 Jan 2022 21:38:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643233121; bh=0ecxNlw62WJvra/OF+IRNXwztuf5U1ZovPthVp24nSQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AX1hK+TSKreuoWTxwy2SoEkBiJd1PLC9xxTxgcTgf8s5jCGEpFNcr/AthESmPOqt3 WNHsU4mcilnm3W5VjoUTXmCCiwnafW065aC3ka4y8u/rWxkujFIqW4M4yx0mQCIyYu nt7wvOYqbtoyuovOa45rehHDPuqesR2T2Q3+uaVcksDoCTmWZnq7EiO9xIDfJdCDkt YNBtXE0R/DqQkw+zmQaTY1k1I0Dp4NGtDEzsWmpgNhSniynL47+GUm1T65fkvT3J3H i0kdyulnLLWgZ5PQTSIfhu365pTqyZbv71PureX78iRmo4pXP4fyUJsLQYQSJIhGm5 JtahrOxRQ+kVA== Date: Wed, 26 Jan 2022 23:38:34 +0200 From: Mike Rapoport To: Ard Biesheuvel Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: make 'highmem' symbol ro_after_init Message-ID: References: <20220124170555.1054480-1-ardb@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220124170555.1054480-1-ardb@kernel.org> X-Stat-Signature: m6jmmwitqj6x3ywgsgdffbycigi1a4jy X-Rspam-User: nil Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=AX1hK+TS; spf=pass (imf14.hostedemail.com: domain of rppt@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 64CBA10000C X-HE-Tag: 1643233124-676623 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000157, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jan 24, 2022 at 06:05:55PM +0100, Ard Biesheuvel wrote: > The 'highmem' variable is only set at boot, so we can make it > ro_after_init and prevent it from being corrupted inadvertently, or from > ending up in a contended cacheline. > > Signed-off-by: Ard Biesheuvel Acked-by: Mike Rapoport > --- > mm/memory.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memory.c b/mm/memory.c > index c125c4969913..50e82cb94ccc 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -106,7 +106,7 @@ EXPORT_SYMBOL(mem_map); > * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL > * and ZONE_HIGHMEM. > */ > -void *high_memory; > +void *high_memory __ro_after_init; > EXPORT_SYMBOL(high_memory); > > /* > -- > 2.30.2 > > -- Sincerely yours, Mike.