From nobody Thu Dec 18 00:47:14 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68C5CC004C0 for ; Sat, 21 Oct 2023 14:44:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231347AbjJUOoj (ORCPT ); Sat, 21 Oct 2023 10:44:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231496AbjJUOog (ORCPT ); Sat, 21 Oct 2023 10:44:36 -0400 Received: from out-198.mta1.migadu.com (out-198.mta1.migadu.com [IPv6:2001:41d0:203:375::c6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9CE310CF for ; Sat, 21 Oct 2023 07:44:27 -0700 (PDT) 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=1697899466; 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=tHWic5xUklM9ZxSjedPZ6GHTnBcatj0QDeFJJJdaZnI=; b=xZpLnPA5vle6JTPcFbJ0n67rIsmg5XrvSZmL7TRfIktWc0DANpJ7X1ziqse/jIv0Pz1dUf o7Qc3QwNW64n42WyqJ9gTrBPvWfFdigRhBwW2USYW3Yx3/zSf5l0CB9wXdlFqaxE+Px/su W+CQPFSDyncBRZEtuylakjuQDjHwMzc= From: chengming.zhou@linux.dev To: cl@linux.com, penberg@kernel.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, vbabka@suse.cz, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, willy@infradead.org, pcc@google.com, tytso@mit.edu, maz@kernel.org, ruansy.fnst@fujitsu.com, vishal.moola@gmail.com, lrh2000@pku.edu.cn, hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v2 5/6] slub: Introduce get_cpu_partial() Date: Sat, 21 Oct 2023 14:43:16 +0000 Message-Id: <20231021144317.3400916-6-chengming.zhou@linux.dev> In-Reply-To: <20231021144317.3400916-1-chengming.zhou@linux.dev> References: <20231021144317.3400916-1-chengming.zhou@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Chengming Zhou Since the slabs on cpu partial list are not frozen anymore, we introduce get_cpu_partial() to get a frozen slab with its freelist from cpu partial list. It's now much like getting a frozen slab with its freelist from node partial list. Another change is about get_partial(), which can return no frozen slab when all slabs are failed when acquire_slab(), but get some unfreeze slabs in its cpu partial list, so we need to check this rare case to avoid allocating a new slab. Signed-off-by: Chengming Zhou --- mm/slub.c | 87 +++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 68 insertions(+), 19 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 9f0b80fefc70..7fae959c56eb 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3055,6 +3055,68 @@ static inline void *get_freelist(struct kmem_cache *= s, struct slab *slab) return freelist; } =20 +#ifdef CONFIG_SLUB_CPU_PARTIAL + +static void *get_cpu_partial(struct kmem_cache *s, struct kmem_cache_cpu *= c, + struct slab **slabptr, int node, gfp_t gfpflags) +{ + unsigned long flags; + struct slab *slab; + struct slab new; + unsigned long counters; + void *freelist; + + while (slub_percpu_partial(c)) { + local_lock_irqsave(&s->cpu_slab->lock, flags); + if (unlikely(!slub_percpu_partial(c))) { + local_unlock_irqrestore(&s->cpu_slab->lock, flags); + /* we were preempted and partial list got empty */ + return NULL; + } + + slab =3D slub_percpu_partial(c); + slub_set_percpu_partial(c, slab); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); + stat(s, CPU_PARTIAL_ALLOC); + + if (unlikely(!node_match(slab, node) || + !pfmemalloc_match(slab, gfpflags))) { + slab->next =3D NULL; + __unfreeze_partials(s, slab); + continue; + } + + do { + freelist =3D slab->freelist; + counters =3D slab->counters; + + new.counters =3D counters; + VM_BUG_ON(new.frozen); + + new.inuse =3D slab->objects; + new.frozen =3D 1; + } while (!__slab_update_freelist(s, slab, + freelist, counters, + NULL, new.counters, + "get_cpu_partial")); + + *slabptr =3D slab; + return freelist; + } + + return NULL; +} + +#else /* CONFIG_SLUB_CPU_PARTIAL */ + +static void *get_cpu_partial(struct kmem_cache *s, struct kmem_cache_cpu *= c, + struct slab **slabptr, int node, gfp_t gfpflags) +{ + return NULL; +} + +#endif + /* * Slow path. The lockless freelist is empty or we need to perform * debugging duties. @@ -3097,7 +3159,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_= t gfpflags, int node, node =3D NUMA_NO_NODE; goto new_slab; } -redo: =20 if (unlikely(!node_match(slab, node))) { /* @@ -3173,24 +3234,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp= _t gfpflags, int node, =20 new_slab: =20 - if (slub_percpu_partial(c)) { - local_lock_irqsave(&s->cpu_slab->lock, flags); - if (unlikely(c->slab)) { - local_unlock_irqrestore(&s->cpu_slab->lock, flags); - goto reread_slab; - } - if (unlikely(!slub_percpu_partial(c))) { - local_unlock_irqrestore(&s->cpu_slab->lock, flags); - /* we were preempted and partial list got empty */ - goto new_objects; - } - - slab =3D c->slab =3D slub_percpu_partial(c); - slub_set_percpu_partial(c, slab); - local_unlock_irqrestore(&s->cpu_slab->lock, flags); - stat(s, CPU_PARTIAL_ALLOC); - goto redo; - } + freelist =3D get_cpu_partial(s, c, &slab, node, gfpflags); + if (freelist) + goto retry_load_slab; =20 new_objects: =20 @@ -3201,6 +3247,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_= t gfpflags, int node, if (freelist) goto check_new_slab; =20 + if (slub_percpu_partial(c)) + goto new_slab; + slub_put_cpu_ptr(s->cpu_slab); slab =3D new_slab(s, gfpflags, node); c =3D slub_get_cpu_ptr(s->cpu_slab); --=20 2.20.1