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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 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 A5F07C433DF for ; Fri, 10 Jul 2020 08:24:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85CD4206A5 for ; Fri, 10 Jul 2020 08:24:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726832AbgGJIYT (ORCPT ); Fri, 10 Jul 2020 04:24:19 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:60707 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726369AbgGJIYS (ORCPT ); Fri, 10 Jul 2020 04:24:18 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R621e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07488;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=17;SR=0;TI=SMTPD_---0U2HLiLc_1594369452; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U2HLiLc_1594369452) by smtp.aliyun-inc.com(127.0.0.1); Fri, 10 Jul 2020 16:24:13 +0800 Subject: Re: [PATCH v14 07/20] mm/thp: narrow lru locking To: "Kirill A. Shutemov" , Hugh Dickins Cc: Matthew Wilcox , Johannes Weiner , akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com, lkp@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, shakeelb@google.com, iamjoonsoo.kim@lge.com, richard.weiyang@gmail.com References: <1593752873-4493-1-git-send-email-alex.shi@linux.alibaba.com> <1593752873-4493-8-git-send-email-alex.shi@linux.alibaba.com> <124eeef1-ff2b-609e-3bf6-a118100c3f2a@linux.alibaba.com> <20200706113513.GY25523@casper.infradead.org> <20200709154816.wieg5thfejyv2h2l@box> From: Alex Shi Message-ID: Date: Fri, 10 Jul 2020 16:23:35 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200709154816.wieg5thfejyv2h2l@box> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2020/7/9 ÏÂÎç11:48, Kirill A. Shutemov дµÀ: > On Mon, Jul 06, 2020 at 09:52:34PM -0700, Hugh Dickins wrote: >> On Mon, 6 Jul 2020, Matthew Wilcox wrote: >>> On Mon, Jul 06, 2020 at 05:15:09PM +0800, Alex Shi wrote: >>>> Hi Kirill & Johannes & Matthew, >> >> Adding Kirill, who was in patch's Cc list but not mail's Cc list. >> >> I asked Alex to direct this one particularly to Kirill and Johannes >> and Matthew because (and I regret that the commit message still does >> not make this at all clear) this patch changes the lock ordering: >> which for years has been lru_lock outside memcg move_lock outside >> i_pages lock, but here inverted to lru_lock inside i_pages lock. >> >> I don't see a strong reason to have them one way round or the other, >> and think Alex is right that they can safely be reversed here: but >> he doesn't actually give any reason for doing so (if cleanup, then >> I think the cleanup should have been taken further), and no reason >> for doing so as part of this series. > > I've looked around and changing order of lru_lock wrt. i_pages lock seems > safe. I don't have much experience with memcg move_lock. Hi Kirill, Thanks for response! mem_cgroup_move_account(page) could not reach here since 2 blocks, 1, isolate_lru_page() before it will take page from lru, this compete for page reclaim path, list non-null. 2, try_lock_page in it, will guard split_huge_page(), !list. > > Alex, if you are going ahead with the patch, please document the locking > order. We have some locking orders listed at the beginning of filemap.c > and rmap.c. Thanks for reminder! Hugh Dickins did this in above 2 files at the end of patchset, any comments? diff --git a/mm/filemap.c b/mm/filemap.c index f0ae9a6308cb..1b42aaae4d3e 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -101,8 +101,8 @@ * ->swap_lock (try_to_unmap_one) * ->private_lock (try_to_unmap_one) * ->i_pages lock (try_to_unmap_one) - * ->pgdat->lru_lock (follow_page->mark_page_accessed) - * ->pgdat->lru_lock (check_pte_range->isolate_lru_page) + * ->lruvec->lru_lock (follow_page->mark_page_accessed) + * ->lruvec->lru_lock (check_pte_range->isolate_lru_page) * ->private_lock (page_remove_rmap->set_page_dirty) * ->i_pages lock (page_remove_rmap->set_page_dirty) * bdi.wb->list_lock (page_remove_rmap->set_page_dirty) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d5e56be42f21..926d7d95dc1d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3057,7 +3057,7 @@ void __memcg_kmem_uncharge_page(struct page *page, int order) #ifdef CONFIG_TRANSPARENT_HUGEPAGE /* - * Because tail pages are not marked as "used", set it. We're under + * Because tail pages are not marked as "used", set it. Don't need * lruvec->lru_lock and migration entries setup in all page mappings. */ void mem_cgroup_split_huge_fixup(struct page *head) diff --git a/mm/rmap.c b/mm/rmap.c index 5fe2dedce1fc..7fbc382e6f9e 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -28,12 +28,12 @@ * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) * anon_vma->rwsem * mm->page_table_lock or pte_lock - * pgdat->lru_lock (in mark_page_accessed, isolate_lru_page) * swap_lock (in swap_duplicate, swap_info_get) * mmlist_lock (in mmput, drain_mmlist and others) * mapping->private_lock (in __set_page_dirty_buffers) - * mem_cgroup_{begin,end}_page_stat (memcg->move_lock) + * lock_page_memcg move_lock (in __set_page_dirty_buffers) * i_pages lock (widely used) + * lock_page_lruvec_irq lruvec->lru_lock * inode->i_lock (in set_page_dirty's __mark_inode_dirty) * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) * sb_lock (within inode_lock in fs/fs-writeback.c) > > local_irq_disable() also deserves a comment. > yes, I will add a comment for this. Do you mind give reviewed-by for this patch? Thanks Alex