From nobody Mon Apr 6 22:09:57 2026 Received: from mail-dl1-f73.google.com (mail-dl1-f73.google.com [74.125.82.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 33D7E3FA5D3 for ; Tue, 17 Mar 2026 23:07:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773788849; cv=none; b=i/0mxAl0kSYOrYS5db2SB8EtTQb8Q7gxtCd2ZmmYJPRvrSF7OIjtNmHFMczEpwCFOc3kkGz7m1gV8Qe7de+btXrba4imU+sm7lkFw42Cq/XwBGHX4Bur3nfGluMqkavZon7JxZWjbkl6TcE0VQ0yOYr1H8jUINd3O59NAOtje7c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773788849; c=relaxed/simple; bh=ZfWE2COIH+ldGUo90wdzJ/MxDEymNSaHSsDjounjNKw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ZrMq1fDXkZp9bQjcvASk3mbMOq45nNjXHGCNkOM0aPnSplH1WQUP/XsbxOfn5rVldDeAqgeGFuhheNhWhC8LX8lV42Qgy+hMbknyJ0dXMc+gMKjxSqFdgqw2qI0/TMnmYsbiwhphFWrDuVGrD9rSBRd8tuqEiiKMiDKkqOZ+mrE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--bingjiao.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=D5UjtZbv; arc=none smtp.client-ip=74.125.82.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--bingjiao.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="D5UjtZbv" Received: by mail-dl1-f73.google.com with SMTP id a92af1059eb24-128edc72e5bso5636631c88.1 for ; Tue, 17 Mar 2026 16:07:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1773788847; x=1774393647; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=2sLkrHizaGZBp890B7+nzygesvVkoY/tFf4Qx2iHrc0=; b=D5UjtZbv3NJS6j8ZtyKUljmjPFX3Bd52ycLqWXTKwyBlR+Ebja4J3fpcSYNqFAF8/k ox4ickECjfEHg8yBCX1MJiyB755Qk0eClW52q7t1+dLc4gyHnBS70m8PESLg5N2Nj5a9 jKlx8WzWsxun/9DUxHMDrCr7GVZoRMImoMC/WLnkhRusFdAGAE/eSZ/FeN5yJmCOlLxb 0ZD1jOvHx8+1/cEpfnhFMjkhIrJsK8pri6gSKxLQYR+it8VbuDZ2LRp9V94oYyNVpvgB r9LY0IgvBFpsAPS+FhGqkUGRX+nhupv4+cFFE5xErxQkadnfIwGzQXz0R6C//bPvNqKS tlWA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773788847; x=1774393647; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=2sLkrHizaGZBp890B7+nzygesvVkoY/tFf4Qx2iHrc0=; b=CDpjDFNkyHCFZjpAOI6qtmXt6bMoTR6qxKgV3gAij1Ua0jo5dz1XG+by4yzX7paHR2 yg0pfKCI/xQX5TTONMY4JEjgADur2xmNdovFGXgIS9y7avXd8fIOtgtby6OLGdLgodde yckWOPBagdlrWztUqNsMnFpZBhsOK3sjZCKnFe4qpTOk7VRJWuUvDb14YfDDxjCmNdGd aB/MShs7fBorQQgTooCrI/3zZ+wBvC4NGn23UKQC67TgPg25zpdOIBrIcrObJ5YPfInL V3iF3swmX20xM/6/E0eCWzNgyt6bqyT/mE3F2stbtsan0/2/mQFeaTMRLmMfpWzulS7L JjaQ== X-Forwarded-Encrypted: i=1; AJvYcCVF2Et2AZcJoOVDNqkNoJT5z4rcBBln+qTpFLg0Hgw48bPgByGhfyrOGDeGtu3vC6P1N54zjv2fGfcGEIg=@vger.kernel.org X-Gm-Message-State: AOJu0Yzc5VJ99HYa1QGETt7sKGCD8b5u+8a/3nzcqAt4XFr9Z8fpl7M7 KMgYTUJZcqXI+YWKTSRDNdZViNSXevo69rrgR5j1DlDp0xVvmsHmVSrfE9VyWJNw3v5UYtcVu2f 9f+WU9gz39IBUsA== X-Received: from dlbrn2.prod.google.com ([2002:a05:7022:1502:b0:128:d185:c6ff]) (user=bingjiao job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:2218:b0:119:e569:fb9b with SMTP id a92af1059eb24-129a7111483mr694227c88.10.1773788846767; Tue, 17 Mar 2026 16:07:26 -0700 (PDT) Date: Tue, 17 Mar 2026 23:07:02 +0000 In-Reply-To: <20260317230720.990329-1-bingjiao@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260317230720.990329-1-bingjiao@google.com> X-Mailer: git-send-email 2.53.0.851.ga537e3e6e9-goog Message-ID: <20260317230720.990329-4-bingjiao@google.com> Subject: [PATCH 3/3] mm/vmscan: add demote= option to proactive reclaim From: Bing Jiao To: linux-mm@kvack.org Cc: Bing Jiao , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , David Rientjes , Yosry Ahmed , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , David Hildenbrand , Qi Zheng , Lorenzo Stoakes , Axel Rasmussen , Yuanchu Xie , Wei Xu , Joshua Hahn Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In tiered-memory systems, proactive memory reclaim (via the cgroup memory.reclaim interface) can demote pages to a lower memory tier before eventually reclaiming them to swap. Add a 'demote=3D%u' option to memory.reclaim to allow users to control this behavior. Setting 'demote=3D1' enables demotion, while 'demote=3D0' disables it. By default, demote is disabled (0). This change ensures that proactive reclaim behaves consistently with cgroup limit-based reclaim (e.g., memory.high), where the goal is typically to reduce the overall memory footprint rather than migrating it to slower tiers. Signed-off-by: Bing Jiao --- mm/vmscan.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index 7a8617ba1748..80194270fa2e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -7878,11 +7878,13 @@ static unsigned long __node_reclaim(struct pglist_d= ata *pgdat, gfp_t gfp_mask, enum { MEMORY_RECLAIM_SWAPPINESS =3D 0, MEMORY_RECLAIM_SWAPPINESS_MAX, + MEMORY_RECLAIM_ALLOW_DEMOTION, MEMORY_RECLAIM_NULL, }; static const match_table_t tokens =3D { { MEMORY_RECLAIM_SWAPPINESS, "swappiness=3D%d"}, { MEMORY_RECLAIM_SWAPPINESS_MAX, "swappiness=3Dmax"}, + { MEMORY_RECLAIM_ALLOW_DEMOTION, "demote=3D%u"}, { MEMORY_RECLAIM_NULL, NULL }, }; @@ -7890,6 +7892,7 @@ int user_proactive_reclaim(char *buf, struct mem_cgroup *memcg, pg_data_t *pgdat) { unsigned int nr_retries =3D MAX_RECLAIM_RETRIES; + unsigned int allow_demotion =3D 0; unsigned long nr_to_reclaim, nr_reclaimed =3D 0; int swappiness =3D -1; char *old_buf, *start; @@ -7922,6 +7925,10 @@ int user_proactive_reclaim(char *buf, case MEMORY_RECLAIM_SWAPPINESS_MAX: swappiness =3D SWAPPINESS_ANON_ONLY; break; + case MEMORY_RECLAIM_ALLOW_DEMOTION: + if (match_uint(&args[0], &allow_demotion)) + return -EINVAL; + break; default: return -EINVAL; } @@ -7947,6 +7954,8 @@ int user_proactive_reclaim(char *buf, reclaim_options =3D MEMCG_RECLAIM_MAY_SWAP | MEMCG_RECLAIM_PROACTIVE; + if (!allow_demotion) + reclaim_options |=3D MEMCG_RECLAIM_NO_DEMOTION; reclaimed =3D try_to_free_mem_cgroup_pages(memcg, batch_size, gfp_mask, reclaim_options, @@ -7962,6 +7971,7 @@ int user_proactive_reclaim(char *buf, .may_unmap =3D 1, .may_swap =3D 1, .proactive =3D 1, + .no_demotion =3D !(allow_demotion), }; if (test_and_set_bit_lock(PGDAT_RECLAIM_LOCKED, -- 2.53.0.851.ga537e3e6e9-goog