From nobody Wed Dec 31 16:18:21 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 D8B47C00142 for ; Tue, 31 Oct 2023 14:09:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231389AbjJaOJI (ORCPT ); Tue, 31 Oct 2023 10:09:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbjJaOJF (ORCPT ); Tue, 31 Oct 2023 10:09:05 -0400 Received: from out-179.mta1.migadu.com (out-179.mta1.migadu.com [IPv6:2001:41d0:203:375::b3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA376C1 for ; Tue, 31 Oct 2023 07:09:02 -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=1698761341; 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=V/1IQ8DC4Ww2WANT0Yk1WGGMP6T1XolwvFVe/nWWtdo=; b=fWm3Ia9WLFuFmGWFVj3nkTO3KKIcArYI3sKwoNpxt4Vp+VSnp85jAdULf4fwS1xOUGBFRy qaL4xq+9jHvu/YO3QBypb2sb88cVvTthrSNRtZkaROqU8A7pGtYB9RLWsXKVwXBPAiXyCD wIoAlyBL54p89iiOAU9sfE8NjzIGnzM= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 1/9] slub: Reflow ___slab_alloc() Date: Tue, 31 Oct 2023 14:07:33 +0000 Message-Id: <20231031140741.79387-2-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 The get_partial() interface used in ___slab_alloc() may return a single object in the "kmem_cache_debug(s)" case, in which we will just return the "freelist" object. Move this handling up to prepare for later changes. And the "pfmemalloc_match()" part is not needed for node partial slab, since we already check this in the get_partial_node(). Signed-off-by: Chengming Zhou Reviewed-by: Vlastimil Babka Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 63d281dfacdb..0b0fdc8c189f 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3216,8 +3216,21 @@ static void *___slab_alloc(struct kmem_cache *s, gfp= _t gfpflags, int node, pc.slab =3D &slab; pc.orig_size =3D orig_size; freelist =3D get_partial(s, node, &pc); - if (freelist) - goto check_new_slab; + if (freelist) { + if (kmem_cache_debug(s)) { + /* + * For debug caches here we had to go through + * alloc_single_from_partial() so just store the + * tracking info and return the object. + */ + if (s->flags & SLAB_STORE_USER) + set_track(s, freelist, TRACK_ALLOC, addr); + + return freelist; + } + + goto retry_load_slab; + } =20 slub_put_cpu_ptr(s->cpu_slab); slab =3D new_slab(s, gfpflags, node); @@ -3253,20 +3266,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp= _t gfpflags, int node, =20 inc_slabs_node(s, slab_nid(slab), slab->objects); =20 -check_new_slab: - - if (kmem_cache_debug(s)) { - /* - * For debug caches here we had to go through - * alloc_single_from_partial() so just store the tracking info - * and return the object - */ - if (s->flags & SLAB_STORE_USER) - set_track(s, freelist, TRACK_ALLOC, addr); - - return freelist; - } - if (unlikely(!pfmemalloc_match(slab, gfpflags))) { /* * For !pfmemalloc_match() case we don't load freelist so that --=20 2.20.1 From nobody Wed Dec 31 16:18:21 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 482EEC4167B for ; Tue, 31 Oct 2023 14:09:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231421AbjJaOJK (ORCPT ); Tue, 31 Oct 2023 10:09:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231286AbjJaOJI (ORCPT ); Tue, 31 Oct 2023 10:09:08 -0400 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A73AE6 for ; Tue, 31 Oct 2023 07:09:05 -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=1698761343; 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=GvFpTjudBUawLgUZhfA4XumfhFt8DHF3SUizR1gsSN0=; b=TXFp5ZrS2RLrdK40RbVab8YMC1O20QrLDJHbtWDv0h7N6MLbta00vjmZGm7DnKTG5RBgxq h6YdjNWfhUe2h4dCRzYErdTwo+9MGcYO5LIMetNw+He4mdD9iExl/e/+7gz+qY3n+fIq95 TDslQnTghxmWva6tPEM6zC6/ZgI5/0A= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 2/9] slub: Change get_partial() interfaces to return slab Date: Tue, 31 Oct 2023 14:07:34 +0000 Message-Id: <20231031140741.79387-3-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 We need all get_partial() related interfaces to return a slab, instead of returning the freelist (or object). Use the partial_context.object to return back freelist or object for now. This patch shouldn't have any functional changes. Suggested-by: Vlastimil Babka Signed-off-by: Chengming Zhou Reviewed-by: Vlastimil Babka Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 63 +++++++++++++++++++++++++++++-------------------------- 1 file changed, 33 insertions(+), 30 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 0b0fdc8c189f..03384cd965c5 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -204,9 +204,9 @@ DEFINE_STATIC_KEY_FALSE(slub_debug_enabled); =20 /* Structure holding parameters for get_partial() call chain */ struct partial_context { - struct slab **slab; gfp_t flags; unsigned int orig_size; + void *object; }; =20 static inline bool kmem_cache_debug(struct kmem_cache *s) @@ -2269,10 +2269,11 @@ static inline bool pfmemalloc_match(struct slab *sl= ab, gfp_t gfpflags); /* * Try to allocate a partial slab from a specific node. */ -static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node= *n, - struct partial_context *pc) +static struct slab *get_partial_node(struct kmem_cache *s, + struct kmem_cache_node *n, + struct partial_context *pc) { - struct slab *slab, *slab2; + struct slab *slab, *slab2, *partial =3D NULL; void *object =3D NULL; unsigned long flags; unsigned int partial_slabs =3D 0; @@ -2288,27 +2289,28 @@ static void *get_partial_node(struct kmem_cache *s,= struct kmem_cache_node *n, =20 spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry_safe(slab, slab2, &n->partial, slab_list) { - void *t; - if (!pfmemalloc_match(slab, pc->flags)) continue; =20 if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) { object =3D alloc_single_from_partial(s, n, slab, pc->orig_size); - if (object) + if (object) { + partial =3D slab; + pc->object =3D object; break; + } continue; } =20 - t =3D acquire_slab(s, n, slab, object =3D=3D NULL); - if (!t) + object =3D acquire_slab(s, n, slab, object =3D=3D NULL); + if (!object) break; =20 - if (!object) { - *pc->slab =3D slab; + if (!partial) { + partial =3D slab; + pc->object =3D object; stat(s, ALLOC_FROM_PARTIAL); - object =3D t; } else { put_cpu_partial(s, slab, 0); stat(s, CPU_PARTIAL_NODE); @@ -2324,20 +2326,21 @@ static void *get_partial_node(struct kmem_cache *s,= struct kmem_cache_node *n, =20 } spin_unlock_irqrestore(&n->list_lock, flags); - return object; + return partial; } =20 /* * Get a slab from somewhere. Search in increasing NUMA distances. */ -static void *get_any_partial(struct kmem_cache *s, struct partial_context = *pc) +static struct slab *get_any_partial(struct kmem_cache *s, + struct partial_context *pc) { #ifdef CONFIG_NUMA struct zonelist *zonelist; struct zoneref *z; struct zone *zone; enum zone_type highest_zoneidx =3D gfp_zone(pc->flags); - void *object; + struct slab *slab; unsigned int cpuset_mems_cookie; =20 /* @@ -2372,8 +2375,8 @@ static void *get_any_partial(struct kmem_cache *s, st= ruct partial_context *pc) =20 if (n && cpuset_zone_allowed(zone, pc->flags) && n->nr_partial > s->min_partial) { - object =3D get_partial_node(s, n, pc); - if (object) { + slab =3D get_partial_node(s, n, pc); + if (slab) { /* * Don't check read_mems_allowed_retry() * here - if mems_allowed was updated in @@ -2381,7 +2384,7 @@ static void *get_any_partial(struct kmem_cache *s, st= ruct partial_context *pc) * between allocation and the cpuset * update */ - return object; + return slab; } } } @@ -2393,17 +2396,18 @@ static void *get_any_partial(struct kmem_cache *s, = struct partial_context *pc) /* * Get a partial slab, lock it and return it. */ -static void *get_partial(struct kmem_cache *s, int node, struct partial_co= ntext *pc) +static struct slab *get_partial(struct kmem_cache *s, int node, + struct partial_context *pc) { - void *object; + struct slab *slab; int searchnode =3D node; =20 if (node =3D=3D NUMA_NO_NODE) searchnode =3D numa_mem_id(); =20 - object =3D get_partial_node(s, get_node(s, searchnode), pc); - if (object || node !=3D NUMA_NO_NODE) - return object; + slab =3D get_partial_node(s, get_node(s, searchnode), pc); + if (slab || node !=3D NUMA_NO_NODE) + return slab; =20 return get_any_partial(s, pc); } @@ -3213,10 +3217,10 @@ static void *___slab_alloc(struct kmem_cache *s, gf= p_t gfpflags, int node, new_objects: =20 pc.flags =3D gfpflags; - pc.slab =3D &slab; pc.orig_size =3D orig_size; - freelist =3D get_partial(s, node, &pc); - if (freelist) { + slab =3D get_partial(s, node, &pc); + if (slab) { + freelist =3D pc.object; if (kmem_cache_debug(s)) { /* * For debug caches here we had to go through @@ -3408,12 +3412,11 @@ static void *__slab_alloc_node(struct kmem_cache *s, void *object; =20 pc.flags =3D gfpflags; - pc.slab =3D &slab; pc.orig_size =3D orig_size; - object =3D get_partial(s, node, &pc); + slab =3D get_partial(s, node, &pc); =20 - if (object) - return object; + if (slab) + return pc.object; =20 slab =3D new_slab(s, gfpflags, node); if (unlikely(!slab)) { --=20 2.20.1 From nobody Wed Dec 31 16:18:21 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 4BE7FC4332F for ; Tue, 31 Oct 2023 14:09:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233271AbjJaOJO (ORCPT ); Tue, 31 Oct 2023 10:09:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231286AbjJaOJL (ORCPT ); Tue, 31 Oct 2023 10:09:11 -0400 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [IPv6:2001:41d0:203:375::b5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 492E9F1 for ; Tue, 31 Oct 2023 07:09:08 -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=1698761346; 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=A++jOVGS7LIP72VwRB52HksoP76pYwnYqPVPh8XlVaY=; b=e0oJj347aPZSwbHKIh3vXLsSkKARGwrOKNnsPyGmHd3T7kZSTXQX3ogXWfbcaQarI3N9T+ K6a8+/g2w/Lvo1/fNOwaYaNltKZM0McSUApZ+72CI1R6rJaPoGntDGGb/xG8G5fgvNBo8e 6XB8zAf1SLuL1e087s8VurnX6PJPY5s= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 3/9] slub: Keep track of whether slub is on the per-node partial list Date: Tue, 31 Oct 2023 14:07:35 +0000 Message-Id: <20231031140741.79387-4-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 Now we rely on the "frozen" bit to see if we should manipulate the slab->slab_list, which will be changed in the following patch. Instead we introduce another way to keep track of whether slub is on the per-node partial list, here we reuse the PG_workingset bit. We use __set_bit and __clear_bit directly instead of the atomic version for better performance and it's safe since it's protected by the slub node list_lock. Suggested-by: Matthew Wilcox Signed-off-by: Chengming Zhou Reviewed-by: Vlastimil Babka Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/mm/slub.c b/mm/slub.c index 03384cd965c5..eed8ae0dbaf9 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2116,6 +2116,25 @@ static void discard_slab(struct kmem_cache *s, struc= t slab *slab) free_slab(s, slab); } =20 +/* + * SLUB reuses PG_workingset bit to keep track of whether it's on + * the per-node partial list. + */ +static inline bool slab_test_node_partial(const struct slab *slab) +{ + return folio_test_workingset((struct folio *)slab_folio(slab)); +} + +static inline void slab_set_node_partial(struct slab *slab) +{ + __set_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); +} + +static inline void slab_clear_node_partial(struct slab *slab) +{ + __clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); +} + /* * Management of partially allocated slabs. */ @@ -2127,6 +2146,7 @@ __add_partial(struct kmem_cache_node *n, struct slab = *slab, int tail) list_add_tail(&slab->slab_list, &n->partial); else list_add(&slab->slab_list, &n->partial); + slab_set_node_partial(slab); } =20 static inline void add_partial(struct kmem_cache_node *n, @@ -2141,6 +2161,7 @@ static inline void remove_partial(struct kmem_cache_n= ode *n, { lockdep_assert_held(&n->list_lock); list_del(&slab->slab_list); + slab_clear_node_partial(slab); n->nr_partial--; } =20 @@ -4833,6 +4854,7 @@ static int __kmem_cache_do_shrink(struct kmem_cache *= s) =20 if (free =3D=3D slab->objects) { list_move(&slab->slab_list, &discard); + slab_clear_node_partial(slab); n->nr_partial--; dec_slabs_node(s, node, slab->objects); } else if (free <=3D SHRINK_PROMOTE_MAX) --=20 2.20.1 From nobody Wed Dec 31 16:18:21 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 E954FC4167B for ; Tue, 31 Oct 2023 14:09:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232429AbjJaOJR (ORCPT ); Tue, 31 Oct 2023 10:09:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233719AbjJaOJO (ORCPT ); Tue, 31 Oct 2023 10:09:14 -0400 Received: from out-185.mta1.migadu.com (out-185.mta1.migadu.com [95.215.58.185]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39D9D115 for ; Tue, 31 Oct 2023 07:09:11 -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=1698761349; 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=v/W13f1yvwrCHZgH+TSl+cdWReIuGoRVTB5psVe8An4=; b=wNIpzakvsd93W80vtkHwQf555uZ1X7UCHSu5UZdhAwR+WInzzIHY0wg3MqdVqIXyuFrveg zfUzHrnr02/YVCm2lpOuVKjDOu31IpZFnrJaagZexEAqG5577/evBuPT6k6264Mc9xVBB2 K4yu/KTcypElGi304xzyFujmguhhPdg= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 4/9] slub: Prepare __slab_free() for unfrozen partial slab out of node partial list Date: Tue, 31 Oct 2023 14:07:36 +0000 Message-Id: <20231031140741.79387-5-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 Now the partially empty slub will be frozen when taken out of node partial list, so the __slab_free() will know from "was_frozen" that the partially empty slab is not on node partial list and is a cpu or cpu partial slab of some cpu. But we will change this, make partial slabs leave the node partial list with unfrozen state, so we need to change __slab_free() to use the new slab_test_node_partial() we just introduced. Signed-off-by: Chengming Zhou Reviewed-by: Vlastimil Babka Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/mm/slub.c b/mm/slub.c index eed8ae0dbaf9..1880b483350e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3631,6 +3631,7 @@ static void __slab_free(struct kmem_cache *s, struct = slab *slab, unsigned long counters; struct kmem_cache_node *n =3D NULL; unsigned long flags; + bool on_node_partial; =20 stat(s, FREE_SLOWPATH); =20 @@ -3678,6 +3679,7 @@ static void __slab_free(struct kmem_cache *s, struct = slab *slab, */ spin_lock_irqsave(&n->list_lock, flags); =20 + on_node_partial =3D slab_test_node_partial(slab); } } =20 @@ -3706,6 +3708,15 @@ static void __slab_free(struct kmem_cache *s, struct= slab *slab, return; } =20 + /* + * This slab was partially empty but not on the per-node partial list, + * in which case we shouldn't manipulate its list, just return. + */ + if (prior && !on_node_partial) { + spin_unlock_irqrestore(&n->list_lock, flags); + return; + } + if (unlikely(!new.inuse && n->nr_partial >=3D s->min_partial)) goto slab_empty; =20 --=20 2.20.1 From nobody Wed Dec 31 16:18:21 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 DFB8EC4167D for ; Tue, 31 Oct 2023 14:09:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235507AbjJaOJZ (ORCPT ); Tue, 31 Oct 2023 10:09:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233536AbjJaOJQ (ORCPT ); Tue, 31 Oct 2023 10:09:16 -0400 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14BA0125 for ; Tue, 31 Oct 2023 07:09:13 -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=1698761352; 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=DSV2hJzhN1EMBaKNKe5GTqHBigf8Oik9SH9kDO4tfhs=; b=WHMjfXAw75r95lcc5nFUiMN89Tof/YlZMyVPqZKNOdvO1yteE6uHCrbGBMOqY7xCBTII+D bv4O0JIZHkzqYTy9jSpAEEAubWuuo1+LX71TrqtSTlbNRuljW0aerBJZZx3KeiAGfHntFE 9WQV2XL6SGskdWaTT/AwR5nu7UHQO8I= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 5/9] slub: Introduce freeze_slab() Date: Tue, 31 Oct 2023 14:07:37 +0000 Message-Id: <20231031140741.79387-6-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 We will have unfrozen slabs out of the node partial list later, so we need a freeze_slab() function to freeze the partial slab and get its freelist. Signed-off-by: Chengming Zhou Reviewed-by: Vlastimil Babka Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/mm/slub.c b/mm/slub.c index 1880b483350e..edf567971679 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3098,6 +3098,33 @@ static inline void *get_freelist(struct kmem_cache *= s, struct slab *slab) return freelist; } =20 +/* + * Freeze the partial slab and return the pointer to the freelist. + */ +static inline void *freeze_slab(struct kmem_cache *s, struct slab *slab) +{ + struct slab new; + unsigned long counters; + void *freelist; + + 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, + "freeze_slab")); + + return freelist; +} + /* * Slow path. The lockless freelist is empty or we need to perform * debugging duties. --=20 2.20.1 From nobody Wed Dec 31 16:18:21 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 C68F7C4332F for ; Tue, 31 Oct 2023 14:09:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232223AbjJaOJb (ORCPT ); Tue, 31 Oct 2023 10:09:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233464AbjJaOJY (ORCPT ); Tue, 31 Oct 2023 10:09:24 -0400 Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [IPv6:2001:41d0:203:375::b4]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F7F4133 for ; Tue, 31 Oct 2023 07:09:16 -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=1698761355; 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=WFFMQyhLZJnEzwgDfbrlXS+sPYcJwR5pdI64P4BtRGU=; b=T7PF2RDxrnhml9AGrzBwH7Qb6gebmTAsuAiIOValuuZMya2Gd9T1jQvXTSlgNdQynWleC7 BIbYj4Hhvn5EHHFj1uNZNgRFHhPDpDZmezPhOhX5zL2VsVdotFZfFjnqhG8XarSBkxuXgN ddq0HXNsmojE5zrxEzjWz16CJWMGtZU= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 6/9] slub: Delay freezing of partial slabs Date: Tue, 31 Oct 2023 14:07:38 +0000 Message-Id: <20231031140741.79387-7-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 Now we will freeze slabs when moving them out of node partial list to cpu partial list, this method needs two cmpxchg_double operations: 1. freeze slab (acquire_slab()) under the node list_lock 2. get_freelist() when pick used in ___slab_alloc() Actually we don't need to freeze when moving slabs out of node partial list, we can delay freezing to when use slab freelist in ___slab_alloc(), so we can save one cmpxchg_double(). And there are other good points: - The moving of slabs between node partial list and cpu partial list becomes simpler, since we don't need to freeze or unfreeze at all. - The node list_lock contention would be less, since we don't need to freeze any slab under the node list_lock. We can achieve this because there is no concurrent path would manipulate the partial slab list except the __slab_free() path, which is now serialized by slab_test_node_partial() under the list_lock. Since the slab returned by get_partial() interfaces is not frozen anymore and no freelist is returned in the partial_context, so we need to use the introduced freeze_slab() to freeze it and get its freelist. Similarly, the slabs on the CPU partial list are not frozen anymore, we need to freeze_slab() on it before use. We can now delete acquire_slab() as it became unused. Signed-off-by: Chengming Zhou Reviewed-by: Vlastimil Babka Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 113 +++++++++++------------------------------------------- 1 file changed, 23 insertions(+), 90 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index edf567971679..bcb5b2c4e213 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2234,51 +2234,6 @@ static void *alloc_single_from_new_slab(struct kmem_= cache *s, return object; } =20 -/* - * Remove slab from the partial list, freeze it and - * return the pointer to the freelist. - * - * Returns a list of objects or NULL if it fails. - */ -static inline void *acquire_slab(struct kmem_cache *s, - struct kmem_cache_node *n, struct slab *slab, - int mode) -{ - void *freelist; - unsigned long counters; - struct slab new; - - lockdep_assert_held(&n->list_lock); - - /* - * Zap the freelist and set the frozen bit. - * The old freelist is the list of objects for the - * per cpu allocation list. - */ - freelist =3D slab->freelist; - counters =3D slab->counters; - new.counters =3D counters; - if (mode) { - new.inuse =3D slab->objects; - new.freelist =3D NULL; - } else { - new.freelist =3D freelist; - } - - VM_BUG_ON(new.frozen); - new.frozen =3D 1; - - if (!__slab_update_freelist(s, slab, - freelist, counters, - new.freelist, new.counters, - "acquire_slab")) - return NULL; - - remove_partial(n, slab); - WARN_ON(!freelist); - return freelist; -} - #ifdef CONFIG_SLUB_CPU_PARTIAL static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int d= rain); #else @@ -2295,7 +2250,6 @@ static struct slab *get_partial_node(struct kmem_cach= e *s, struct partial_context *pc) { struct slab *slab, *slab2, *partial =3D NULL; - void *object =3D NULL; unsigned long flags; unsigned int partial_slabs =3D 0; =20 @@ -2314,7 +2268,7 @@ static struct slab *get_partial_node(struct kmem_cach= e *s, continue; =20 if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) { - object =3D alloc_single_from_partial(s, n, slab, + void *object =3D alloc_single_from_partial(s, n, slab, pc->orig_size); if (object) { partial =3D slab; @@ -2324,13 +2278,10 @@ static struct slab *get_partial_node(struct kmem_ca= che *s, continue; } =20 - object =3D acquire_slab(s, n, slab, object =3D=3D NULL); - if (!object) - break; + remove_partial(n, slab); =20 if (!partial) { partial =3D slab; - pc->object =3D object; stat(s, ALLOC_FROM_PARTIAL); } else { put_cpu_partial(s, slab, 0); @@ -2629,9 +2580,6 @@ static void __unfreeze_partials(struct kmem_cache *s,= struct slab *partial_slab) unsigned long flags =3D 0; =20 while (partial_slab) { - struct slab new; - struct slab old; - slab =3D partial_slab; partial_slab =3D slab->next; =20 @@ -2644,23 +2592,7 @@ static void __unfreeze_partials(struct kmem_cache *s= , struct slab *partial_slab) spin_lock_irqsave(&n->list_lock, flags); } =20 - do { - - old.freelist =3D slab->freelist; - old.counters =3D slab->counters; - VM_BUG_ON(!old.frozen); - - new.counters =3D old.counters; - new.freelist =3D old.freelist; - - new.frozen =3D 0; - - } while (!__slab_update_freelist(s, slab, - old.freelist, old.counters, - new.freelist, new.counters, - "unfreezing slab")); - - if (unlikely(!new.inuse && n->nr_partial >=3D s->min_partial)) { + if (unlikely(!slab->inuse && n->nr_partial >=3D s->min_partial)) { slab->next =3D slab_to_discard; slab_to_discard =3D slab; } else { @@ -3167,7 +3099,6 @@ 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))) { /* @@ -3243,7 +3174,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_= t gfpflags, int node, =20 new_slab: =20 - if (slub_percpu_partial(c)) { +#ifdef CONFIG_SLUB_CPU_PARTIAL + while (slub_percpu_partial(c)) { local_lock_irqsave(&s->cpu_slab->lock, flags); if (unlikely(c->slab)) { local_unlock_irqrestore(&s->cpu_slab->lock, flags); @@ -3255,12 +3187,22 @@ static void *___slab_alloc(struct kmem_cache *s, gf= p_t gfpflags, int node, goto new_objects; } =20 - slab =3D c->slab =3D slub_percpu_partial(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; + + if (unlikely(!node_match(slab, node) || + !pfmemalloc_match(slab, gfpflags))) { + slab->next =3D NULL; + __unfreeze_partials(s, slab); + continue; + } + + freelist =3D freeze_slab(s, slab); + goto retry_load_slab; } +#endif =20 new_objects: =20 @@ -3268,8 +3210,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_= t gfpflags, int node, pc.orig_size =3D orig_size; slab =3D get_partial(s, node, &pc); if (slab) { - freelist =3D pc.object; if (kmem_cache_debug(s)) { + freelist =3D pc.object; /* * For debug caches here we had to go through * alloc_single_from_partial() so just store the @@ -3281,6 +3223,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_= t gfpflags, int node, return freelist; } =20 + freelist =3D freeze_slab(s, slab); goto retry_load_slab; } =20 @@ -3682,18 +3625,8 @@ static void __slab_free(struct kmem_cache *s, struct= slab *slab, was_frozen =3D new.frozen; new.inuse -=3D cnt; if ((!new.inuse || !prior) && !was_frozen) { - - if (kmem_cache_has_cpu_partial(s) && !prior) { - - /* - * Slab was on no list before and will be - * partially empty - * We can defer the list move and instead - * freeze it. - */ - new.frozen =3D 1; - - } else { /* Needs to be taken off a list */ + /* Needs to be taken off a list */ + if (!kmem_cache_has_cpu_partial(s) || prior) { =20 n =3D get_node(s, slab_nid(slab)); /* @@ -3723,9 +3656,9 @@ static void __slab_free(struct kmem_cache *s, struct = slab *slab, * activity can be necessary. */ stat(s, FREE_FROZEN); - } else if (new.frozen) { + } else if (kmem_cache_has_cpu_partial(s) && !prior) { /* - * If we just froze the slab then put it onto the + * If we started with a full slab then put it onto the * per cpu partial list. */ put_cpu_partial(s, slab, 1); --=20 2.20.1 From nobody Wed Dec 31 16:18:21 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 47B85C4332F for ; Tue, 31 Oct 2023 14:09:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235803AbjJaOJe (ORCPT ); Tue, 31 Oct 2023 10:09:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234896AbjJaOJY (ORCPT ); Tue, 31 Oct 2023 10:09:24 -0400 Received: from out-175.mta1.migadu.com (out-175.mta1.migadu.com [95.215.58.175]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2B0A183 for ; Tue, 31 Oct 2023 07:09:19 -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=1698761358; 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=71jccDuvmHUN0B2hAN0chVUZ3a/I3ZWuScusSDMRbZM=; b=EgWg7JyuljiAgmtHeNxZPVDCEzu19y0onJXhXs8aae8cO3ZMQHroKY26QyUFiFaebUhzCc RGV6bWjUO05MthcYp2hTuKmvk++h80PzPUQqKT6vJe0w3lTBc8M2DdpDA2JE+ug45MtF26 X/0C77Wy9EZYl/zFaNFqEn7aLM2cGT8= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 7/9] slub: Optimize deactivate_slab() Date: Tue, 31 Oct 2023 14:07:39 +0000 Message-Id: <20231031140741.79387-8-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 introduce of unfrozen slabs on cpu partial list, we don't need to synchronize the slab frozen state under the node list_lock. The caller of deactivate_slab() and the caller of __slab_free() won't manipulate the slab list concurrently. So we can get node list_lock in the last stage if we really need to manipulate the slab list in this path. Signed-off-by: Chengming Zhou Reviewed-by: Vlastimil Babka Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 76 +++++++++++++++++++------------------------------------ 1 file changed, 26 insertions(+), 50 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index bcb5b2c4e213..c429f8baba5f 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2468,10 +2468,8 @@ static void init_kmem_cache_cpus(struct kmem_cache *= s) static void deactivate_slab(struct kmem_cache *s, struct slab *slab, void *freelist) { - enum slab_modes { M_NONE, M_PARTIAL, M_FREE, M_FULL_NOLIST }; struct kmem_cache_node *n =3D get_node(s, slab_nid(slab)); int free_delta =3D 0; - enum slab_modes mode =3D M_NONE; void *nextfree, *freelist_iter, *freelist_tail; int tail =3D DEACTIVATE_TO_HEAD; unsigned long flags =3D 0; @@ -2512,62 +2510,40 @@ static void deactivate_slab(struct kmem_cache *s, s= truct slab *slab, * * Ensure that the slab is unfrozen while the list presence * reflects the actual number of objects during unfreeze. - * - * We first perform cmpxchg holding lock and insert to list - * when it succeed. If there is mismatch then the slab is not - * unfrozen and number of objects in the slab may have changed. - * Then release lock and retry cmpxchg again. */ -redo: - - old.freelist =3D READ_ONCE(slab->freelist); - old.counters =3D READ_ONCE(slab->counters); - VM_BUG_ON(!old.frozen); - - /* Determine target state of the slab */ - new.counters =3D old.counters; - if (freelist_tail) { - new.inuse -=3D free_delta; - set_freepointer(s, freelist_tail, old.freelist); - new.freelist =3D freelist; - } else - new.freelist =3D old.freelist; - - new.frozen =3D 0; + do { + old.freelist =3D READ_ONCE(slab->freelist); + old.counters =3D READ_ONCE(slab->counters); + VM_BUG_ON(!old.frozen); + + /* Determine target state of the slab */ + new.counters =3D old.counters; + new.frozen =3D 0; + if (freelist_tail) { + new.inuse -=3D free_delta; + set_freepointer(s, freelist_tail, old.freelist); + new.freelist =3D freelist; + } else { + new.freelist =3D old.freelist; + } + } while (!slab_update_freelist(s, slab, + old.freelist, old.counters, + new.freelist, new.counters, + "unfreezing slab")); =20 + /* + * Stage three: Manipulate the slab list based on the updated state. + */ if (!new.inuse && n->nr_partial >=3D s->min_partial) { - mode =3D M_FREE; + stat(s, DEACTIVATE_EMPTY); + discard_slab(s, slab); + stat(s, FREE_SLAB); } else if (new.freelist) { - mode =3D M_PARTIAL; - /* - * Taking the spinlock removes the possibility that - * acquire_slab() will see a slab that is frozen - */ spin_lock_irqsave(&n->list_lock, flags); - } else { - mode =3D M_FULL_NOLIST; - } - - - if (!slab_update_freelist(s, slab, - old.freelist, old.counters, - new.freelist, new.counters, - "unfreezing slab")) { - if (mode =3D=3D M_PARTIAL) - spin_unlock_irqrestore(&n->list_lock, flags); - goto redo; - } - - - if (mode =3D=3D M_PARTIAL) { add_partial(n, slab, tail); spin_unlock_irqrestore(&n->list_lock, flags); stat(s, tail); - } else if (mode =3D=3D M_FREE) { - stat(s, DEACTIVATE_EMPTY); - discard_slab(s, slab); - stat(s, FREE_SLAB); - } else if (mode =3D=3D M_FULL_NOLIST) { + } else { stat(s, DEACTIVATE_FULL); } } --=20 2.20.1 From nobody Wed Dec 31 16:18:21 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 BAF69C4332F for ; Tue, 31 Oct 2023 14:09:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233390AbjJaOJm (ORCPT ); Tue, 31 Oct 2023 10:09:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235514AbjJaOJZ (ORCPT ); Tue, 31 Oct 2023 10:09:25 -0400 Received: from out-179.mta1.migadu.com (out-179.mta1.migadu.com [95.215.58.179]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B79B9121 for ; Tue, 31 Oct 2023 07:09:22 -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=1698761361; 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=WNirFUhouaQ2FdRmy2RjQgkCONe7ugTNtD0fPI9SkvQ=; b=r1MiH4vM84Jj3nwHog6emae9i1zx3YqzKMYp0IBEloU7g/8tB45Y1H9zMFiMKQbkD/H0Qe VuvBkAF8ea4irChfcbAhAq0tXL092g71ipfL7eKZwrga14ekhl47LZcRSrMGn4jQOfzSeP bhCSvGRNAWF820iIR0MuX+4oZgKIP/E= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 8/9] slub: Rename all *unfreeze_partials* functions to *put_partials* Date: Tue, 31 Oct 2023 14:07:40 +0000 Message-Id: <20231031140741.79387-9-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 all partial slabs on the CPU partial list are not frozen anymore, we don't unfreeze when moving cpu partial slabs to node partial list, it's better to rename these functions. Signed-off-by: Chengming Zhou Reviewed-by: Vlastimil Babka Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index c429f8baba5f..bb7368047103 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2549,7 +2549,7 @@ static void deactivate_slab(struct kmem_cache *s, str= uct slab *slab, } =20 #ifdef CONFIG_SLUB_CPU_PARTIAL -static void __unfreeze_partials(struct kmem_cache *s, struct slab *partial= _slab) +static void put_partials_node(struct kmem_cache *s, struct slab *partial_s= lab) { struct kmem_cache_node *n =3D NULL, *n2 =3D NULL; struct slab *slab, *slab_to_discard =3D NULL; @@ -2591,9 +2591,9 @@ static void __unfreeze_partials(struct kmem_cache *s,= struct slab *partial_slab) } =20 /* - * Unfreeze all the cpu partial slabs. + * Put all the cpu partial slabs to the node partial list. */ -static void unfreeze_partials(struct kmem_cache *s) +static void put_partials(struct kmem_cache *s) { struct slab *partial_slab; unsigned long flags; @@ -2604,11 +2604,11 @@ static void unfreeze_partials(struct kmem_cache *s) local_unlock_irqrestore(&s->cpu_slab->lock, flags); =20 if (partial_slab) - __unfreeze_partials(s, partial_slab); + put_partials_node(s, partial_slab); } =20 -static void unfreeze_partials_cpu(struct kmem_cache *s, - struct kmem_cache_cpu *c) +static void put_partials_cpu(struct kmem_cache *s, + struct kmem_cache_cpu *c) { struct slab *partial_slab; =20 @@ -2616,7 +2616,7 @@ static void unfreeze_partials_cpu(struct kmem_cache *= s, c->partial =3D NULL; =20 if (partial_slab) - __unfreeze_partials(s, partial_slab); + put_partials_node(s, partial_slab); } =20 /* @@ -2629,7 +2629,7 @@ static void unfreeze_partials_cpu(struct kmem_cache *= s, static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int d= rain) { struct slab *oldslab; - struct slab *slab_to_unfreeze =3D NULL; + struct slab *slab_to_put =3D NULL; unsigned long flags; int slabs =3D 0; =20 @@ -2644,7 +2644,7 @@ static void put_cpu_partial(struct kmem_cache *s, str= uct slab *slab, int drain) * per node partial list. Postpone the actual unfreezing * outside of the critical section. */ - slab_to_unfreeze =3D oldslab; + slab_to_put =3D oldslab; oldslab =3D NULL; } else { slabs =3D oldslab->slabs; @@ -2660,17 +2660,17 @@ static void put_cpu_partial(struct kmem_cache *s, s= truct slab *slab, int drain) =20 local_unlock_irqrestore(&s->cpu_slab->lock, flags); =20 - if (slab_to_unfreeze) { - __unfreeze_partials(s, slab_to_unfreeze); + if (slab_to_put) { + put_partials_node(s, slab_to_put); stat(s, CPU_PARTIAL_DRAIN); } } =20 #else /* CONFIG_SLUB_CPU_PARTIAL */ =20 -static inline void unfreeze_partials(struct kmem_cache *s) { } -static inline void unfreeze_partials_cpu(struct kmem_cache *s, - struct kmem_cache_cpu *c) { } +static inline void put_partials(struct kmem_cache *s) { } +static inline void put_partials_cpu(struct kmem_cache *s, + struct kmem_cache_cpu *c) { } =20 #endif /* CONFIG_SLUB_CPU_PARTIAL */ =20 @@ -2712,7 +2712,7 @@ static inline void __flush_cpu_slab(struct kmem_cache= *s, int cpu) stat(s, CPUSLAB_FLUSH); } =20 - unfreeze_partials_cpu(s, c); + put_partials_cpu(s, c); } =20 struct slub_flush_work { @@ -2740,7 +2740,7 @@ static void flush_cpu_slab(struct work_struct *w) if (c->slab) flush_slab(s, c); =20 - unfreeze_partials(s); + put_partials(s); } =20 static bool has_cpu_slab(int cpu, struct kmem_cache *s) @@ -3171,7 +3171,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_= t gfpflags, int node, if (unlikely(!node_match(slab, node) || !pfmemalloc_match(slab, gfpflags))) { slab->next =3D NULL; - __unfreeze_partials(s, slab); + put_partials_node(s, slab); continue; } =20 --=20 2.20.1 From nobody Wed Dec 31 16:18:21 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 32E36C4332F for ; Tue, 31 Oct 2023 14:09:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235274AbjJaOJq (ORCPT ); Tue, 31 Oct 2023 10:09:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235747AbjJaOJb (ORCPT ); Tue, 31 Oct 2023 10:09:31 -0400 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [IPv6:2001:41d0:203:375::b5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26E4019E for ; Tue, 31 Oct 2023 07:09:25 -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=1698761363; 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=1rWlR4h5g4eDWf2XTzUlOrJLNxfEOq6mT+00ilTz0G0=; b=Y0fRMVJblxItnO7fa29gryhY0OuDSuYpX3u9Ss3dhqwRf1OZ/GJBzbFxGqASfXa3ZkcDEd llhl/Boestl6/Pzbcckw30/f5cm8ZIVtqAPveVEahzHWy0Mm0D45/0Br2r/TLM+w+opTst LbLFwmWZyebAWLmuYs8XzdN4+enFRJY= From: chengming.zhou@linux.dev To: vbabka@suse.cz, cl@linux.com, penberg@kernel.org, willy@infradead.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH v4 9/9] slub: Update frozen slabs documentations in the source Date: Tue, 31 Oct 2023 14:07:41 +0000 Message-Id: <20231031140741.79387-10-chengming.zhou@linux.dev> In-Reply-To: <20231031140741.79387-1-chengming.zhou@linux.dev> References: <20231031140741.79387-1-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 The current updated scheme (which this series implemented) is: - node partial slabs: PG_Workingset && !frozen - cpu partial slabs: !PG_Workingset && !frozen - cpu slabs: !PG_Workingset && frozen - full slabs: !PG_Workingset && !frozen The most important change is that "frozen" bit is not set for the cpu partial slabs anymore, __slab_free() will grab node list_lock then check by !PG_Workingset that it's not on a node partial list. And the "frozen" bit is still kept for the cpu slabs for performance, since we don't need to grab node list_lock to check whether the PG_Workingset is set or not if the "frozen" bit is set in __slab_free(). Update related documentations and comments in the source. Signed-off-by: Chengming Zhou Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- mm/slub.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index bb7368047103..89d3f7a18a73 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -76,13 +76,22 @@ * * Frozen slabs * - * If a slab is frozen then it is exempt from list management. It is not - * on any list except per cpu partial list. The processor that froze the + * If a slab is frozen then it is exempt from list management. It is + * the cpu slab which is actively allocated from by the processor that + * froze it and it is not on any list. The processor that froze the * slab is the one who can perform list operations on the slab. Other * processors may put objects onto the freelist but the processor that * froze the slab is the only one that can retrieve the objects from the * slab's freelist. * + * CPU partial slabs + * + * The partially empty slabs cached on the CPU partial list are used + * for performance reasons, which speeds up the allocation process. + * These slabs are not frozen, but also exempt from list management, + * by clearing the PG_workingset flag when moving out of the node + * partial list. Please see __slab_free() for more details. + * * list_lock * * The list_lock protects the partial and full list on each node and @@ -2620,8 +2629,7 @@ static void put_partials_cpu(struct kmem_cache *s, } =20 /* - * Put a slab that was just frozen (in __slab_free|get_partial_node) into a - * partial slab slot if available. + * Put a slab into a partial slab slot if available. * * If we did not find a slot then simply move all the partials to the * per node partial list. --=20 2.20.1