From nobody Tue Feb 10 05:17:02 2026 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (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 B828132C933 for ; Thu, 23 Oct 2025 13:53:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761227612; cv=none; b=C6o9RVe6z0Uc3CikvdwqUKyl3NZ9PlQBE9301WZQx2bYM0nhRzRCFa7lI/bc9F8PosILxkubE5RiKwbNLVi6K8E6eGvYqK9sKGBstReHFljc0aZnXTTVHP3c63ZhAYMYNBZmjryCd9PytIdgzfgRx1nBX0bkdjrfY9RkWbX5o8A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761227612; c=relaxed/simple; bh=iykOLqpENh8I3toWK/77E6dRFS9AWDujWVD3b/qJNK4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=FBTJ2+VyG/o61QJ2NsrGaowK+45GKJOA/VXtfjJOsbKuSGLd1jN2A2NGDqrLcrmhZbeLAuwB/VmwjhDCBsyj8b7/3FJG1LFVxs/eiNTV5uUEtKH1u7ZNyfzaWJloxbpc1Fzq/ofb0vL9Kn3Olu7xMZyhoUqGN8KLl1LT9TttDYA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz; spf=pass smtp.mailfrom=suse.cz; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.cz Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id A95971F7CA; Thu, 23 Oct 2025 13:53:01 +0000 (UTC) Authentication-Results: smtp-out2.suse.de; none Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 4F60413B0B; Thu, 23 Oct 2025 13:52:54 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id QOT/EjYz+mjvQQAAD6G6ig (envelope-from ); Thu, 23 Oct 2025 13:52:54 +0000 From: Vlastimil Babka Date: Thu, 23 Oct 2025 15:52:35 +0200 Subject: [PATCH RFC 13/19] slab: remove defer_deactivate_slab() 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 Message-Id: <20251023-sheaves-for-all-v1-13-6ffa2c9941c0@suse.cz> References: <20251023-sheaves-for-all-v1-0-6ffa2c9941c0@suse.cz> In-Reply-To: <20251023-sheaves-for-all-v1-0-6ffa2c9941c0@suse.cz> To: Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo Cc: Uladzislau Rezki , "Liam R. Howlett" , Suren Baghdasaryan , Sebastian Andrzej Siewior , Alexei Starovoitov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, bpf@vger.kernel.org, kasan-dev@googlegroups.com, Vlastimil Babka X-Mailer: b4 0.14.3 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spam-Level: X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spamd-Result: default: False [-4.00 / 50.00]; REPLY(-4.00)[] X-Rspamd-Queue-Id: A95971F7CA X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -4.00 There are no more cpu slabs so we don't need their deferred deactivation. The function is now only used from a place where we allocate a new slab but then can't spin on node list_lock to put it on the partial list. Instead of the deferred action we can free it directly via __free_slab(), we just need to tell it to use _nolock() freeing of the underlying pages and take care of the accounting. Since free_frozen_pages_nolock() variant does not yet exist for code outside of the page allocator, create it as a trivial wrapper for __free_frozen_pages(..., FPI_TRYLOCK). Signed-off-by: Vlastimil Babka --- mm/internal.h | 1 + mm/page_alloc.c | 5 +++++ mm/slab.h | 8 +------- mm/slub.c | 50 +++++++++++++++----------------------------------- 4 files changed, 22 insertions(+), 42 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 1561fc2ff5b8..64c5eda7c1ae 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -846,6 +846,7 @@ static inline struct page *alloc_frozen_pages_noprof(gf= p_t gfp, unsigned int ord struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, un= signed int order); #define alloc_frozen_pages_nolock(...) \ alloc_hooks(alloc_frozen_pages_nolock_noprof(__VA_ARGS__)) +void free_frozen_pages_nolock(struct page *page, unsigned int order); =20 extern void zone_pcp_reset(struct zone *zone); extern void zone_pcp_disable(struct zone *zone); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 600d9e981c23..f8ac3232db41 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2944,6 +2944,11 @@ void free_frozen_pages(struct page *page, unsigned i= nt order) __free_frozen_pages(page, order, FPI_NONE); } =20 +void free_frozen_pages_nolock(struct page *page, unsigned int order) +{ + __free_frozen_pages(page, order, FPI_TRYLOCK); +} + /* * Free a batch of folios */ diff --git a/mm/slab.h b/mm/slab.h index a103da44ab9d..b2663cc594f3 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -55,13 +55,7 @@ struct slab { struct kmem_cache *slab_cache; union { struct { - union { - struct list_head slab_list; - struct { /* For deferred deactivate_slab() */ - struct llist_node llnode; - void *flush_freelist; - }; - }; + struct list_head slab_list; /* Double-word boundary */ union { struct { diff --git a/mm/slub.c b/mm/slub.c index a35eb397caa9..6f5ca26bbb00 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3246,7 +3246,7 @@ static struct slab *new_slab(struct kmem_cache *s, gf= p_t flags, int node) flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node); } =20 -static void __free_slab(struct kmem_cache *s, struct slab *slab) +static void __free_slab(struct kmem_cache *s, struct slab *slab, bool allo= w_spin) { struct folio *folio =3D slab_folio(slab); int order =3D folio_order(folio); @@ -3257,14 +3257,18 @@ static void __free_slab(struct kmem_cache *s, struc= t slab *slab) __folio_clear_slab(folio); mm_account_reclaimed_pages(pages); unaccount_slab(slab, order, s); - free_frozen_pages(&folio->page, order); + + if (allow_spin) + free_frozen_pages(&folio->page, order); + else + free_frozen_pages_nolock(&folio->page, order); } =20 static void rcu_free_slab(struct rcu_head *h) { struct slab *slab =3D container_of(h, struct slab, rcu_head); =20 - __free_slab(slab->slab_cache, slab); + __free_slab(slab->slab_cache, slab, true); } =20 static void free_slab(struct kmem_cache *s, struct slab *slab) @@ -3280,7 +3284,7 @@ static void free_slab(struct kmem_cache *s, struct sl= ab *slab) if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) call_rcu(&slab->rcu_head, rcu_free_slab); else - __free_slab(s, slab); + __free_slab(s, slab, true); } =20 static void discard_slab(struct kmem_cache *s, struct slab *slab) @@ -3373,8 +3377,6 @@ static void *alloc_single_from_partial(struct kmem_ca= che *s, return object; } =20 -static void defer_deactivate_slab(struct slab *slab, void *flush_freelist); - /* * Called only for kmem_cache_debug() caches to allocate from a freshly * allocated slab. Allocate a single object instead of whole freelist @@ -3390,8 +3392,12 @@ static void *alloc_single_from_new_slab(struct kmem_= cache *s, struct slab *slab, void *object; =20 if (!allow_spin && !spin_trylock_irqsave(&n->list_lock, flags)) { - /* Unlucky, discard newly allocated slab */ - defer_deactivate_slab(slab, NULL); + /* + * Unlucky, discard newly allocated slab. + * Since it was just allocated, we can skip the actions + * in discard_slab() and free_slab(). + */ + __free_slab(s, slab, false); return NULL; } =20 @@ -5949,7 +5955,6 @@ static void free_to_pcs_bulk(struct kmem_cache *s, si= ze_t size, void **p) =20 struct defer_free { struct llist_head objects; - struct llist_head slabs; struct irq_work work; }; =20 @@ -5957,7 +5962,6 @@ static void free_deferred_objects(struct irq_work *wo= rk); =20 static DEFINE_PER_CPU(struct defer_free, defer_free_objects) =3D { .objects =3D LLIST_HEAD_INIT(objects), - .slabs =3D LLIST_HEAD_INIT(slabs), .work =3D IRQ_WORK_INIT(free_deferred_objects), }; =20 @@ -5970,10 +5974,9 @@ static void free_deferred_objects(struct irq_work *w= ork) { struct defer_free *df =3D container_of(work, struct defer_free, work); struct llist_head *objs =3D &df->objects; - struct llist_head *slabs =3D &df->slabs; struct llist_node *llnode, *pos, *t; =20 - if (llist_empty(objs) && llist_empty(slabs)) + if (llist_empty(objs)) return; =20 llnode =3D llist_del_all(objs); @@ -5997,16 +6000,6 @@ static void free_deferred_objects(struct irq_work *w= ork) =20 __slab_free(s, slab, x, x, 1, _THIS_IP_); } - - llnode =3D llist_del_all(slabs); - llist_for_each_safe(pos, t, llnode) { - struct slab *slab =3D container_of(pos, struct slab, llnode); - - if (slab->frozen) - deactivate_slab(slab->slab_cache, slab, slab->flush_freelist); - else - free_slab(slab->slab_cache, slab); - } } =20 static void defer_free(struct kmem_cache *s, void *head) @@ -6020,19 +6013,6 @@ static void defer_free(struct kmem_cache *s, void *h= ead) irq_work_queue(&df->work); } =20 -static void defer_deactivate_slab(struct slab *slab, void *flush_freelist) -{ - struct defer_free *df; - - slab->flush_freelist =3D flush_freelist; - - guard(preempt)(); - - df =3D this_cpu_ptr(&defer_free_objects); - if (llist_add(&slab->llnode, &df->slabs)) - irq_work_queue(&df->work); -} - void defer_free_barrier(void) { int cpu; --=20 2.51.1