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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT 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 1F6F0C433E6 for ; Wed, 13 Jan 2021 13:16:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9964E23432 for ; Wed, 13 Jan 2021 13:16:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9964E23432 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A67A08D0053; Wed, 13 Jan 2021 08:16:48 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9F09C8D002E; Wed, 13 Jan 2021 08:16:48 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8BA268D0053; Wed, 13 Jan 2021 08:16:48 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0054.hostedemail.com [216.40.44.54]) by kanga.kvack.org (Postfix) with ESMTP id 718488D002E for ; Wed, 13 Jan 2021 08:16:48 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 36EA2824556B for ; Wed, 13 Jan 2021 13:16:48 +0000 (UTC) X-FDA: 77700801696.14.magic21_1f0f6572751e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id 157F118229818 for ; Wed, 13 Jan 2021 13:16:48 +0000 (UTC) X-HE-Tag: magic21_1f0f6572751e X-Filterd-Recvd-Size: 2603 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Wed, 13 Jan 2021 13:16:47 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 61F64B7D4; Wed, 13 Jan 2021 13:16:46 +0000 (UTC) From: Vlastimil Babka To: Andrew Morton , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vladimir Davydov , Qian Cai , David Hildenbrand , Michal Hocko , Vlastimil Babka Subject: [PATCH 0/3] mm, slab, slub: remove cpu and memory hotplug locks Date: Wed, 13 Jan 2021 14:16:31 +0100 Message-Id: <20210113131634.3671-1-vbabka@suse.cz> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 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: Changes since RFC: - lockdep didn't like reintroducing slab_mutex in kmem_cache_shrink(), so instead explain why it's not needed after all (in Patch 2) - the above is only safe with Patch 1 already in place, so order it first (current Patch 1 was Patch 3 in RFC) Some related work caused me to look at how we use get/put_mems_online() a= nd get/put_online_cpus() during kmem cache creation/descruction/shrinking, a= nd realize that it should be actually safe to remove all of that with rather= small effort (as e.g. Michal Hocko suspected in some of the past discussions already). This has the benefit to avoid rather heavy locks that have caus= ed locking order issues already in the past. So this is the result, Patches = 2 and 3 remove memory hotplug and cpu hotplug locking, respectively. Patch 1 is= due to realization that in fact some races exist despite the locks (even if n= ot removed), but the most sane solution is not to introduce more of them, bu= t rather accept some wasted memory in scenarios that should be rare anyway = (full memory hot remove), as we do the same in other contexts already. Vlastimil Babka (3): mm, slub: stop freeing kmem_cache_node structures on node offline mm, slab, slub: stop taking memory hotplug lock mm, slab, slub: stop taking cpu hotplug lock mm/slab_common.c | 18 ++-------------- mm/slub.c | 56 +++++++++++++++++++++++++++++++----------------- 2 files changed, 38 insertions(+), 36 deletions(-) --=20 2.29.2