From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 2C7596B0006 for ; Sat, 4 Aug 2018 20:03:19 -0400 (EDT) Received: by mail-pf1-f199.google.com with SMTP id q21-v6so5967348pff.21 for ; Sat, 04 Aug 2018 17:03:19 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id 67-v6si9964461pfc.21.2018.08.04.17.03.17 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 04 Aug 2018 17:03:17 -0700 (PDT) Date: Sat, 4 Aug 2018 17:03:05 -0700 From: Matthew Wilcox Subject: Re: [PATCH] mm: Use special value SHRINKER_REGISTERING instead list_empty() check Message-ID: <20180805000305.GC3183@bombadil.infradead.org> References: <153331055842.22632.9290331685041037871.stgit@localhost.localdomain> <20180803155120.0d65511b46c100565b4f8a2c@linux-foundation.org> <843169c5-a47a-e6cd-7412-611e72eb20ba@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <843169c5-a47a-e6cd-7412-611e72eb20ba@virtuozzo.com> Sender: owner-linux-mm@kvack.org List-ID: 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 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.