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=-2.4 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 9CA0EC46470 for ; Sun, 5 Aug 2018 12:50:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 531E7217C7 for ; Sun, 5 Aug 2018 12:50:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="OIMgS20c" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 531E7217C7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726540AbeHEOyo (ORCPT ); Sun, 5 Aug 2018 10:54:44 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:36628 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726130AbeHEOyn (ORCPT ); Sun, 5 Aug 2018 10:54:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=TAq9xifJoa7eMv4El7o7rDnPwhNB1LnwshRzNjleeCw=; b=OIMgS20c7JIsavvgQTnuppHCN pnLUr/A16KcabcqKwRmZXUkqN1NCp6b5qi6OvCw8msmhsojzB277q52Xxjp5sC25aG/mzx8SYbJ/P rU8hLdT5fC1/rjHlvJudi7XqmQJVU4owzx93AnrxoS4fSUsEG+Dt7l7IDvgIunxhTLicCkMYoVSM+ yN2MGd9mdf8Rbz5YaFZCA0H2nIjqHlHks9bH/e6X/nIQJrRCrVo6w1pr0iIOJmSOEwYhQwHC39foY 22cW/8ennzpz7cr9J4wdMpwHXUu3F1VPi/7INe+KI7exWStyDFTrTmMeIZ2Ay8x1m1wYFebTJ30/b eX9b7btIw==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1fmIU0-0001N3-77; Sun, 05 Aug 2018 12:50:04 +0000 Date: Sun, 5 Aug 2018 05:50:04 -0700 From: Matthew Wilcox To: Kirill Tkhai Cc: Andrew Morton , vdavydov.dev@gmail.com, mhocko@suse.com, aryabinin@virtuozzo.com, ying.huang@intel.com, penguin-kernel@I-love.SAKURA.ne.jp, shakeelb@google.com, jbacik@fb.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: Use special value SHRINKER_REGISTERING instead list_empty() check Message-ID: <20180805125004.GD3183@bombadil.infradead.org> References: <153331055842.22632.9290331685041037871.stgit@localhost.localdomain> <20180803155120.0d65511b46c100565b4f8a2c@linux-foundation.org> <843169c5-a47a-e6cd-7412-611e72eb20ba@virtuozzo.com> <20180805000305.GC3183@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 05, 2018 at 08:30:43AM +0300, Kirill Tkhai wrote: > On 05.08.2018 03:03, Matthew Wilcox wrote: > > On Sat, Aug 04, 2018 at 09:42:05PM +0300, Kirill Tkhai wrote: > >> This is exactly the thing the patch makes. Instead of inserting a shrinker pointer > >> to idr, it inserts a fake value SHRINKER_REGISTERING there. The patch makes impossible > >> to dereference a shrinker unless it's completely registered. > > > > - id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL); > > + id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL); > > > > Instead: > > > > + id = idr_alloc(&shrinker_idr, NULL, 0, 0, GFP_KERNEL); > > > > ... and the rest of your patch becomes even simpler. > > The patch, we are discussing at the moment, does *exactly* this: > > https://lkml.org/lkml/2018/8/3/588 > > It looks like you missed this hunk in the patch. No, it does this: + id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL); I'm saying do this: + id = idr_alloc(&shrinker_idr, NULL, 0, 0, GFP_KERNEL);