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mm: add WQ_PERCPU to alloc_workqueue users

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't explicitly specify WQ_UNBOUND
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.

[akpm@linux-foundation.org: fix mm/slub.c]
[akpm@linux-foundation.org: fix kmem_cache_init_late() properly, per Sebastian]
Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
Link: https://lkml.kernel.org/r/20260113114630.152942-4-marco.crivellari@suse.com
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lai jiangshan <jiangshanlai@gmail.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

authored by

Marco Crivellari and committed by
Andrew Morton
ed0a826c 73b21621

+5 -3
+1 -1
mm/backing-dev.c
··· 974 974 * system_percpu_wq. Put them in a separate wq and limit concurrency. 975 975 * There's no point in executing many of these in parallel. 976 976 */ 977 - cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1); 977 + cgwb_release_wq = alloc_workqueue("cgwb_release", WQ_PERCPU, 1); 978 978 if (!cgwb_release_wq) 979 979 return -ENOMEM; 980 980
+2 -1
mm/slub.c
··· 8542 8542 8543 8543 void __init kmem_cache_init_late(void) 8544 8544 { 8545 - flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0); 8545 + flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM | WQ_PERCPU, 8546 + 0); 8546 8547 WARN_ON(!flushwq); 8547 8548 } 8548 8549
+2 -1
mm/vmstat.c
··· 2259 2259 { 2260 2260 int ret __maybe_unused; 2261 2261 2262 - mm_percpu_wq = alloc_workqueue("mm_percpu_wq", WQ_MEM_RECLAIM, 0); 2262 + mm_percpu_wq = alloc_workqueue("mm_percpu_wq", 2263 + WQ_MEM_RECLAIM | WQ_PERCPU, 0); 2263 2264 2264 2265 #ifdef CONFIG_SMP 2265 2266 ret = cpuhp_setup_state_nocalls(CPUHP_MM_VMSTAT_DEAD, "mm/vmstat:dead",