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Tue, 13 Jan 2026 03:46:46 -0800 (PST) Received: from linux ([2a00:6d43:105:c401:e307:1a37:2e76:ce91]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47d7f6953fasm391850225e9.5.2026.01.13.03.46.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Jan 2026 03:46:46 -0800 (PST) From: Marco Crivellari To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Tejun Heo , Lai Jiangshan , Frederic Weisbecker , Sebastian Andrzej Siewior , Marco Crivellari , Michal Hocko , Andrew Morton Subject: [PATCH v2 3/3] mm: add WQ_PERCPU to alloc_workqueue users Date: Tue, 13 Jan 2026 12:46:30 +0100 Message-ID: <20260113114630.152942-4-marco.crivellari@suse.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260113114630.152942-1-marco.crivellari@suse.com> References: <20260113114630.152942-1-marco.crivellari@suse.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable This continues the effort to refactor workqueue APIs, which began with the introduction of new workqueues and a new alloc_workqueue flag in: commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") The refactoring is going to alter the default behavior of alloc_workqueue() to be unbound by default. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn=E2=80=99t explicitly specify WQ_UNB= OUND must now use WQ_PERCPU. For more details see the Link tag below. In order to keep alloc_workqueue() behavior identical, explicitly request WQ_PERCPU. Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/ Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Reviewed-by: Frederic Weisbecker Reviewed-by: Sebastian Andrzej Siewior --- mm/backing-dev.c | 2 +- mm/slub.c | 4 +++- mm/vmstat.c | 3 ++- 3 files changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 4c6f0b85a24e..861fee5e48b7 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -974,7 +974,7 @@ static int __init cgwb_init(void) * system_percpu_wq. Put them in a separate wq and limit concurrency. * There's no point in executing many of these in parallel. */ - cgwb_release_wq =3D alloc_workqueue("cgwb_release", 0, 1); + cgwb_release_wq =3D alloc_workqueue("cgwb_release", WQ_PERCPU, 1); if (!cgwb_release_wq) return -ENOMEM; =20 diff --git a/mm/slub.c b/mm/slub.c index 861592ac5425..bbaa247dce2a 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -8542,7 +8542,9 @@ void __init kmem_cache_init(void) =20 void __init kmem_cache_init_late(void) { - flushwq =3D alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0); +#ifndef CONFIG_SLUB_TINY + flushwq =3D alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM | WQ_PERCPU, + 0); WARN_ON(!flushwq); } =20 diff --git a/mm/vmstat.c b/mm/vmstat.c index 65de88cdf40e..580b5ad293d6 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -2274,7 +2274,8 @@ void __init init_mm_internals(void) { int ret __maybe_unused; =20 - mm_percpu_wq =3D alloc_workqueue("mm_percpu_wq", WQ_MEM_RECLAIM, 0); + mm_percpu_wq =3D alloc_workqueue("mm_percpu_wq", + WQ_MEM_RECLAIM | WQ_PERCPU, 0); =20 #ifdef CONFIG_SMP ret =3D cpuhp_setup_state_nocalls(CPUHP_MM_VMSTAT_DEAD, "mm/vmstat:dead", --=20 2.52.0