From nobody Mon Feb 9 11:51:12 2026 Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 202E7395DAE for ; Wed, 14 Jan 2026 11:36:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768390561; cv=none; b=r6lZP2xchx/n74K9JMErnyS0+X4JN6ezz9jIoAEcjI2RnlDh8HbOIiu8Kt3+wmDbdKY9yRNK1oTqslAgoIhqoNr86n/daDgjBDT22lHAQfzDaBLI/q1biGO9KNi4O6s1zdeiqM+4lR7DlRlflHsh622NasdWd1zv5X35jwLvwrs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768390561; c=relaxed/simple; bh=RMlvOfwkCXrSKdq414J/8rj3i8HQVfygLYwBJobOdV0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iQPnLsF5TKFAf9aT/pGutZGJNIz7VcMji32seAEMzkH8XGihRpYTiEgCAlZ5AXih8EhVHexEt+kt+lOa53ZWOJOAZcpuJMe5TiACXdroSmKks3ObPcVhtHqt5oMEm9+5BGd4YVkDV+zybvlPYQvAAtW3DrhMeG5Gz8eNWvYrE4I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=M6fCdsWR; arc=none smtp.client-ip=91.218.175.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="M6fCdsWR" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1768390558; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nrIiGmzrPddCzyrKZdqDkSj0MgSt0dRpJv5I1+lcafw=; b=M6fCdsWRiOPynPpGQoKa+M9QMkaiLufFtqZyCqB7CkCQpzXxZ/BaAInFTO+f3iCBtlui1E 5QrID4zcWlG2j+JEofg84xWeLhlxNLt/TAw94oXPVS2ieVCRgFvI0wTkiJKx1zof1gwJwl 1OrjEB74AwD5y9miusJ0SyiNPwMEqck= From: Qi Zheng To: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, yosry.ahmed@linux.dev, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Qi Zheng Subject: [PATCH v3 25/30] mm: vmscan: prepare for reparenting traditional LRU folios Date: Wed, 14 Jan 2026 19:32:52 +0800 Message-ID: <3adb367000706f9ef681b34d0a2b0eb34c494c84.1768389889.git.zhengqi.arch@bytedance.com> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Qi Zheng To resolve the dying memcg issue, we need to reparent LRU folios of child memcg to its parent memcg. For traditional LRU list, each lruvec of every memcg comprises four LRU lists. Due to the symmetry of the LRU lists, it is feasible to transfer the LRU lists from a memcg to its parent memcg during the reparenting process. This commit implements the specific function, which will be used during the reparenting process. Signed-off-by: Qi Zheng Reviewed-by: Harry Yoo Acked-by: Johannes Weiner Acked-by: Muchun Song --- include/linux/mmzone.h | 4 ++++ include/linux/swap.h | 19 +++++++++++++++++++ mm/swap.c | 37 +++++++++++++++++++++++++++++++++++++ mm/vmscan.c | 19 ------------------- 4 files changed, 60 insertions(+), 19 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 6a7db0fee54a3..1014b5a93c09c 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -366,6 +366,10 @@ enum lruvec_flags { LRUVEC_NODE_CONGESTED, }; =20 +#ifdef CONFIG_MEMCG +void lru_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *paren= t); +#endif /* CONFIG_MEMCG */ + #endif /* !__GENERATING_BOUNDS_H */ =20 /* diff --git a/include/linux/swap.h b/include/linux/swap.h index e60f45b48e74d..4449d1f371a56 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -636,5 +636,24 @@ static inline bool mem_cgroup_swap_full(struct folio *= folio) } #endif =20 +/* for_each_managed_zone_pgdat - helper macro to iterate over all managed = zones in a pgdat up to + * and including the specified highidx + * @zone: The current zone in the iterator + * @pgdat: The pgdat which node_zones are being iterated + * @idx: The index variable + * @highidx: The index of the highest zone to return + * + * This macro iterates through all managed zones up to and including the s= pecified highidx. + * The zone iterator enters an invalid state after macro call and must be = reinitialized + * before it can be used again. + */ +#define for_each_managed_zone_pgdat(zone, pgdat, idx, highidx) \ + for ((idx) =3D 0, (zone) =3D (pgdat)->node_zones; \ + (idx) <=3D (highidx); \ + (idx)++, (zone)++) \ + if (!managed_zone(zone)) \ + continue; \ + else + #endif /* __KERNEL__*/ #endif /* _LINUX_SWAP_H */ diff --git a/mm/swap.c b/mm/swap.c index 7e53479ca1732..cb40e80da53cd 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -1090,6 +1090,43 @@ void folio_batch_remove_exceptionals(struct folio_ba= tch *fbatch) fbatch->nr =3D j; } =20 +#ifdef CONFIG_MEMCG +static void lruvec_reparent_lru(struct lruvec *child_lruvec, + struct lruvec *parent_lruvec, + enum lru_list lru, int nid) +{ + int zid; + struct zone *zone; + + if (lru !=3D LRU_UNEVICTABLE) + list_splice_tail_init(&child_lruvec->lists[lru], &parent_lruvec->lists[l= ru]); + + for_each_managed_zone_pgdat(zone, NODE_DATA(nid), zid, MAX_NR_ZONES - 1) { + unsigned long size =3D mem_cgroup_get_zone_lru_size(child_lruvec, lru, z= id); + + mem_cgroup_update_lru_size(parent_lruvec, lru, zid, size); + } +} + +void lru_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *paren= t) +{ + int nid; + + for_each_node(nid) { + enum lru_list lru; + struct lruvec *child_lruvec, *parent_lruvec; + + child_lruvec =3D mem_cgroup_lruvec(memcg, NODE_DATA(nid)); + parent_lruvec =3D mem_cgroup_lruvec(parent, NODE_DATA(nid)); + parent_lruvec->anon_cost +=3D child_lruvec->anon_cost; + parent_lruvec->file_cost +=3D child_lruvec->file_cost; + + for_each_lru(lru) + lruvec_reparent_lru(child_lruvec, parent_lruvec, lru, nid); + } +} +#endif + static const struct ctl_table swap_sysctl_table[] =3D { { .procname =3D "page-cluster", diff --git a/mm/vmscan.c b/mm/vmscan.c index c48ff6e05e004..e738082874878 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -270,25 +270,6 @@ static int sc_swappiness(struct scan_control *sc, stru= ct mem_cgroup *memcg) } #endif =20 -/* for_each_managed_zone_pgdat - helper macro to iterate over all managed = zones in a pgdat up to - * and including the specified highidx - * @zone: The current zone in the iterator - * @pgdat: The pgdat which node_zones are being iterated - * @idx: The index variable - * @highidx: The index of the highest zone to return - * - * This macro iterates through all managed zones up to and including the s= pecified highidx. - * The zone iterator enters an invalid state after macro call and must be = reinitialized - * before it can be used again. - */ -#define for_each_managed_zone_pgdat(zone, pgdat, idx, highidx) \ - for ((idx) =3D 0, (zone) =3D (pgdat)->node_zones; \ - (idx) <=3D (highidx); \ - (idx)++, (zone)++) \ - if (!managed_zone(zone)) \ - continue; \ - else - static void set_task_reclaim_state(struct task_struct *task, struct reclaim_state *rs) { --=20 2.20.1