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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 02A51C4741F for ; Thu, 5 Nov 2020 13:14:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA23F20756 for ; Thu, 5 Nov 2020 13:14:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730589AbgKENO2 (ORCPT ); Thu, 5 Nov 2020 08:14:28 -0500 Received: from mx2.suse.de ([195.135.220.15]:57546 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725468AbgKENO1 (ORCPT ); Thu, 5 Nov 2020 08:14:27 -0500 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 049BCABAE; Thu, 5 Nov 2020 13:14:26 +0000 (UTC) To: Michal Hocko Cc: Feng Tang , Andrew Morton , Johannes Weiner , Matthew Wilcox , Mel Gorman , dave.hansen@intel.com, ying.huang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1604470210-124827-1-git-send-email-feng.tang@intel.com> <20201104071308.GN21990@dhcp22.suse.cz> <20201104073826.GA15700@shbuild999.sh.intel.com> <20201104075819.GA10052@dhcp22.suse.cz> <20201104084021.GB15700@shbuild999.sh.intel.com> <20201104085343.GA18718@dhcp22.suse.cz> <20201105014028.GA86777@shbuild999.sh.intel.com> <20201105120818.GC21348@dhcp22.suse.cz> <4029c079-b1f3-f290-26b6-a819c52f5200@suse.cz> <20201105125828.GG21348@dhcp22.suse.cz> From: Vlastimil Babka Subject: Re: [RFC PATCH 0/2] mm: fix OOMs for binding workloads to movable zone only node Message-ID: Date: Thu, 5 Nov 2020 14:14:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201105125828.GG21348@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/5/20 1:58 PM, Michal Hocko wrote: > On Thu 05-11-20 13:53:24, Vlastimil Babka wrote: >> On 11/5/20 1:08 PM, Michal Hocko wrote: >> > On Thu 05-11-20 09:40:28, Feng Tang wrote: >> > > > > Could you be more specific? This sounds like a bug. Allocations >> > > > shouldn't spill over to a node which is not in the cpuset. There are few >> > > > exceptions like IRQ context but that shouldn't happen regurarly. >> > > >> > > I mean when the docker starts, it will spawn many processes which obey >> > > the mem binding set, and they have some kernel page requests, which got >> > > successfully allocated, like the following callstack: >> > > >> > > [ 567.044953] CPU: 1 PID: 2021 Comm: runc:[1:CHILD] Tainted: G W I 5.9.0-rc8+ #6 >> > > [ 567.044956] Hardware name: /NUC6i5SYB, BIOS SYSKLi35.86A.0051.2016.0804.1114 08/04/2016 >> > > [ 567.044958] Call Trace: >> > > [ 567.044972] dump_stack+0x74/0x9a >> > > [ 567.044978] __alloc_pages_nodemask.cold+0x22/0xe5 >> > > [ 567.044986] alloc_pages_current+0x87/0xe0 >> > > [ 567.044991] allocate_slab+0x2e5/0x4f0 >> > > [ 567.044996] ___slab_alloc+0x380/0x5d0 >> > > [ 567.045021] __slab_alloc+0x20/0x40 >> > > [ 567.045025] kmem_cache_alloc+0x2a0/0x2e0 >> > > [ 567.045033] mqueue_alloc_inode+0x1a/0x30 >> > > [ 567.045041] alloc_inode+0x22/0xa0 >> > > [ 567.045045] new_inode_pseudo+0x12/0x60 >> > > [ 567.045049] new_inode+0x17/0x30 >> > > [ 567.045052] mqueue_get_inode+0x45/0x3b0 >> > > [ 567.045060] mqueue_fill_super+0x41/0x70 >> > > [ 567.045067] vfs_get_super+0x7f/0x100 >> > > [ 567.045074] get_tree_keyed+0x1d/0x20 >> > > [ 567.045080] mqueue_get_tree+0x1c/0x20 >> > > [ 567.045086] vfs_get_tree+0x2a/0xc0 >> > > [ 567.045092] fc_mount+0x13/0x50 >> > > [ 567.045099] mq_create_mount+0x92/0xe0 >> > > [ 567.045102] mq_init_ns+0x3b/0x50 >> > > [ 567.045106] copy_ipcs+0x10a/0x1b0 >> > > [ 567.045113] create_new_namespaces+0xa6/0x2b0 >> > > [ 567.045118] unshare_nsproxy_namespaces+0x5a/0xb0 >> > > [ 567.045124] ksys_unshare+0x19f/0x360 >> > > [ 567.045129] __x64_sys_unshare+0x12/0x20 >> > > [ 567.045135] do_syscall_64+0x38/0x90 >> > > [ 567.045143] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> > > >> > > For it, the __alloc_pages_nodemask() will first try process's targed >> > > nodemask(unmovable node here), and there is no availabe zone, so it >> > > goes with the NULL nodemask, and get a page in the slowpath. >> > >> > OK, I see your point now. I was not aware of the slab allocator not >> > following cpusets. Sounds like a bug to me. >> >> SLAB and SLUB seem to not care about cpusets in the fast path. > > Is a fallback to a different node which is outside of the cpuset > possible? AFAICS anything in per-cpu cache will be allocated without looking at the cpuset, so it can be outside of the cpuset. In SLUB slowpath, get_partial_node() looking for fallback on the same node will also not look at cpuset. get_any_partial() looking for a fallback allocation on any node does check cpuset_zone_allowed() and obey it strictly. A fallback to page allocator will obey whatever page allocator obeys. So if a process cannot is restricted to allocate from node X via cpuset *and* also cannot be executed on CPU's from node X via taskset, then it AFAICS effectively cannot violate the cpuset in SLUB because it won't reach the percpu or per-node caches that don't check cpusets. >> But this >> stack shows that it went all the way to the page allocator, so the cpusets >> should have been obeyed there at least. > > Looking closer what is this dump_stack saying actually? Yes, is that a dump of successful allocation (that violates cpusets?) or a failing one?