From nobody Wed Apr 8 12:34:46 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 630E9C433FE for ; Wed, 26 Oct 2022 07:42:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231696AbiJZHmH (ORCPT ); Wed, 26 Oct 2022 03:42:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233331AbiJZHly (ORCPT ); Wed, 26 Oct 2022 03:41:54 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D4A1A4B90; Wed, 26 Oct 2022 00:41:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1666770112; x=1698306112; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=jl6oLzXT4bn5lvPhVCs6xFhXegqNnCjjfs7rohSWfqY=; b=Q6/wOhD3VeZyicRsjyaiaNpVpiV7OFEWbjva551Coa4XeJMovLYasHJU jFTnhRu02Elu8or06/h8I0upGHXfqTDIfr5RIIDHw8+/ErEqp7ZJql8Bm Ovkb6bM+YVr387KeYWL/hWwVjS4NQuGxGU+2nliweWiB0NErjoKnsUGEl wMPvpMgS19RtxRMqdat2Cqj5m11q0omGJ0t0x0Y11tnHrIV01tBe/Yb4m udTMuxn1mq0N72uMXGKE4eu54PlS2xDzqj/6KreKMdoMKDU53IPoIshkr oR5lt+Fayp53drKMjfMhwHiAJ4NNda4LQE0DkLrWMfbw4BGAymJ4Na7BV A==; X-IronPort-AV: E=McAfee;i="6500,9779,10511"; a="308977052" X-IronPort-AV: E=Sophos;i="5.95,214,1661842800"; d="scan'208";a="308977052" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Oct 2022 00:41:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10511"; a="700832747" X-IronPort-AV: E=Sophos;i="5.95,214,1661842800"; d="scan'208";a="700832747" Received: from shbuild999.sh.intel.com ([10.239.146.101]) by fmsmga004.fm.intel.com with ESMTP; 26 Oct 2022 00:41:47 -0700 From: Feng Tang To: Andrew Morton , Johannes Weiner , Michal Hocko , Tejun Heo , Zefan Li , Waiman Long , ying.huang@intel.com, aneesh.kumar@linux.ibm.com, linux-mm@kvack.org, cgroups@vger.kernel.org Cc: linux-kernel@vger.kernel.org, dave.hansen@intel.com, tim.c.chen@intel.com, fengwei.yin@intel.com, Feng Tang Subject: [PATCH] mm/vmscan: respect cpuset policy during page demotion Date: Wed, 26 Oct 2022 15:43:43 +0800 Message-Id: <20221026074343.6517-1-feng.tang@intel.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" In page reclaim path, memory could be demoted from faster memory tier to slower memory tier. Currently, there is no check about cpuset's memory policy, that even if the target demotion node is not allowd by cpuset, the demotion will still happen, which breaks the cpuset semantics. So add cpuset policy check in the demotion path and skip demotion if the demotion targets are not allowed by cpuset. Signed-off-by: Feng Tang --- Hi reviewers, For easy bisectable, I combined the cpuset change and mm change in one patch, if you prefer to separate them, I can turn it into 2 patches. Thanks, Feng include/linux/cpuset.h | 6 ++++++ kernel/cgroup/cpuset.c | 29 +++++++++++++++++++++++++++++ mm/vmscan.c | 35 ++++++++++++++++++++++++++++++++--- 3 files changed, 67 insertions(+), 3 deletions(-) diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index d58e0476ee8e..6fcce2bd2631 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -178,6 +178,8 @@ static inline void set_mems_allowed(nodemask_t nodemask) task_unlock(current); } =20 +extern void cpuset_get_allowed_mem_nodes(struct cgroup *cgroup, + nodemask_t *nmask); #else /* !CONFIG_CPUSETS */ =20 static inline bool cpusets_enabled(void) { return false; } @@ -299,6 +301,10 @@ static inline bool read_mems_allowed_retry(unsigned in= t seq) return false; } =20 +static inline void cpuset_get_allowed_mem_nodes(struct cgroup *cgroup, + nodemask_t *nmask) +{ +} #endif /* !CONFIG_CPUSETS */ =20 #endif /* _LINUX_CPUSET_H */ diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 3ea2e836e93e..cbb118c0502f 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -3750,6 +3750,35 @@ nodemask_t cpuset_mems_allowed(struct task_struct *t= sk) return mask; } =20 +/* + * Retrieve the allowed memory nodemask for a cgroup. + * + * Set *nmask to cpuset's effective allowed nodemask for cgroup v2, + * and NODE_MASK_ALL (means no constraint) for cgroup v1 where there + * is no guaranteed association from a cgroup to a cpuset. + */ +void cpuset_get_allowed_mem_nodes(struct cgroup *cgroup, nodemask_t *nmask) +{ + struct cgroup_subsys_state *css; + struct cpuset *cs; + + if (!is_in_v2_mode()) { + *nmask =3D NODE_MASK_ALL; + return; + } + + rcu_read_lock(); + css =3D cgroup_e_css(cgroup, &cpuset_cgrp_subsys); + if (css) { + css_get(css); + cs =3D css_cs(css); + *nmask =3D cs->effective_mems; + css_put(css); + } + + rcu_read_unlock(); +} + /** * cpuset_nodemask_valid_mems_allowed - check nodemask vs. current mems_al= lowed * @nodemask: the nodemask to be checked diff --git a/mm/vmscan.c b/mm/vmscan.c index 18f6497994ec..c205d98283bc 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1537,9 +1537,21 @@ static struct page *alloc_demote_page(struct page *p= age, unsigned long private) { struct page *target_page; nodemask_t *allowed_mask; - struct migration_target_control *mtc; + struct migration_target_control *mtc =3D (void *)private; =20 - mtc =3D (struct migration_target_control *)private; +#if IS_ENABLED(CONFIG_MEMCG) && IS_ENABLED(CONFIG_CPUSETS) + struct mem_cgroup *memcg; + nodemask_t cpuset_nmask; + + memcg =3D page_memcg(page); + cpuset_get_allowed_mem_nodes(memcg->css.cgroup, &cpuset_nmask); + + if (!node_isset(mtc->nid, cpuset_nmask)) { + if (mtc->nmask) + nodes_and(*mtc->nmask, *mtc->nmask, cpuset_nmask); + return alloc_migration_target(page, (unsigned long)mtc); + } +#endif =20 allowed_mask =3D mtc->nmask; /* @@ -1649,6 +1661,7 @@ static unsigned int shrink_folio_list(struct list_hea= d *folio_list, enum folio_references references =3D FOLIOREF_RECLAIM; bool dirty, writeback; unsigned int nr_pages; + bool skip_this_demotion =3D false; =20 cond_resched(); =20 @@ -1658,6 +1671,22 @@ static unsigned int shrink_folio_list(struct list_he= ad *folio_list, if (!folio_trylock(folio)) goto keep; =20 +#if IS_ENABLED(CONFIG_MEMCG) && IS_ENABLED(CONFIG_CPUSETS) + if (do_demote_pass) { + struct mem_cgroup *memcg; + nodemask_t nmask, nmask1; + + node_get_allowed_targets(pgdat, &nmask); + memcg =3D folio_memcg(folio); + if (memcg) + cpuset_get_allowed_mem_nodes(memcg->css.cgroup, + &nmask1); + + if (!nodes_intersects(nmask, nmask1)) + skip_this_demotion =3D true; + } +#endif + VM_BUG_ON_FOLIO(folio_test_active(folio), folio); =20 nr_pages =3D folio_nr_pages(folio); @@ -1799,7 +1828,7 @@ static unsigned int shrink_folio_list(struct list_hea= d *folio_list, * Before reclaiming the folio, try to relocate * its contents to another node. */ - if (do_demote_pass && + if (do_demote_pass && !skip_this_demotion && (thp_migration_supported() || !folio_test_large(folio))) { list_add(&folio->lru, &demote_folios); folio_unlock(folio); --=20 2.27.0