From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FC45C2B9F7 for ; Mon, 24 May 2021 23:42:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62F45613D8 for ; Mon, 24 May 2021 23:42:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229600AbhEXXnp (ORCPT ); Mon, 24 May 2021 19:43:45 -0400 Received: from mx2.suse.de ([195.135.220.15]:50700 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229953AbhEXXmW (ORCPT ); Mon, 24 May 2021 19:42:22 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1621899649; h=from:from:reply-to: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=Z47ExFtnRGFnfiCGP/JwGcYzfZ2YQagpDfZvgOIHMOM=; b=etD4sdJFbpVk6sGv2tg+Xp2lntEyVckFJOzH45FoRc1fiAkUszCGR2nbcxjPoISzz3jR8q Mafte0RMIp2KZnu48RgOAOHRqi7rW+C40jpreY2DxbuCeDYnnH3aL/EjsfoVskehnfAvOa gtGzVrY5RPxYt4O3mD8HX6NX6XDgvxw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1621899649; h=from:from:reply-to: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=Z47ExFtnRGFnfiCGP/JwGcYzfZ2YQagpDfZvgOIHMOM=; b=PjFn9aSEYXME1fsoPDPInHhzGA5mmfRVp9m3R2c0a4o3QrNof//bNLEcdQX3+oUyRwIyYK O4y+zgWt6MssNZBQ== Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 800C5AF4E; Mon, 24 May 2021 23:40:49 +0000 (UTC) From: Vlastimil Babka To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Peter Zijlstra , Jann Horn , Vlastimil Babka Subject: [RFC 22/26] mm, slub: detach percpu partial list in unfreeze_partials() using this_cpu_cmpxchg() Date: Tue, 25 May 2021 01:39:42 +0200 Message-Id: <20210524233946.20352-23-vbabka@suse.cz> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210524233946.20352-1-vbabka@suse.cz> References: <20210524233946.20352-1-vbabka@suse.cz> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Instead of relying on disabled irqs for atomicity when detaching the percpu partial list, we can use this_cpu_cmpxchg() and detach without irqs disabled. However, unfreeze_partials() can be also called from another cpu on behalf of a cpu that is being offlined, so we need to restructure the code accordingly: - __unfreeze_partials() is the bulk of unfreeze_partials() that processes the detached percpu partial list - unfreeze_partials() uses this_cpu_cmpxchg() to detach list from current cpu - unfreeze_partials_cpu() is to be called for the offlined cpu so it needs no protection, and is called from __flush_cpu_slab() - flush_cpu_slab() needs to call unfreeze_partial() so it can't simply call __flush_cpu_slab(smp_processor_id()) anymore Signed-off-by: Vlastimil Babka --- mm/slub.c | 79 +++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 56 insertions(+), 23 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 414cc621d655..92345d3840d1 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2301,25 +2301,15 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, } } -/* - * Unfreeze all the cpu partial slabs. - * - * This function must be called with preemption or migration - * disabled with c local to the cpu. - */ -static void unfreeze_partials(struct kmem_cache *s, - struct kmem_cache_cpu *c) -{ #ifdef CONFIG_SLUB_CPU_PARTIAL +static void __unfreeze_partials(struct kmem_cache *s, struct page *partial_page) +{ struct kmem_cache_node *n = NULL, *n2 = NULL; - struct page *page, *partial_page, *discard_page = NULL; + struct page *page, *discard_page = NULL; unsigned long flags; local_irq_save(flags); - partial_page = slub_percpu_partial(c); - c->partial = NULL; - while (partial_page) { struct page new; struct page old; @@ -2374,10 +2364,49 @@ static void unfreeze_partials(struct kmem_cache *s, discard_slab(s, page); stat(s, FREE_SLAB); } +} -#endif /* CONFIG_SLUB_CPU_PARTIAL */ +/* + * Unfreeze all the cpu partial slabs. + * + * This function must be called with preemption or migration + * disabled. + */ +static void unfreeze_partials(struct kmem_cache *s) +{ + struct page *partial_page; + + do { + partial_page = this_cpu_read(s->cpu_slab->partial); + + } while (partial_page && + this_cpu_cmpxchg(s->cpu_slab->partial, partial_page, NULL) + != partial_page); + + if (partial_page) + __unfreeze_partials(s, partial_page); } +static void unfreeze_partials_cpu(struct kmem_cache *s, + struct kmem_cache_cpu *c) +{ + struct page *partial_page; + + partial_page = slub_percpu_partial(c); + c->partial = NULL; + + if (partial_page) + __unfreeze_partials(s, partial_page); +} + +#else /* CONFIG_SLUB_CPU_PARTIAL */ + +static void unfreeze_partials(struct kmem_cache *s) { } +static void unfreeze_partials_cpu(struct kmem_cache *s, + struct kmem_cache_cpu *c) { } + +#endif /* CONFIG_SLUB_CPU_PARTIAL */ + /* * Put a page that was just frozen (in __slab_free|get_partial_node) into a * partial page slot if available. @@ -2406,7 +2435,7 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) * partial array is full. Move the existing * set to the per node partial list. */ - unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); + unfreeze_partials(s); oldpage = NULL; pobjects = 0; pages = 0; @@ -2424,7 +2453,7 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage); if (unlikely(!slub_cpu_partial(s))) - unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); + unfreeze_partials(s); preempt_enable(); #endif /* CONFIG_SLUB_CPU_PARTIAL */ @@ -2444,11 +2473,6 @@ static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) stat(s, CPUSLAB_FLUSH); } -/* - * Flush cpu slab. - * - * Called from IPI handler with interrupts disabled. - */ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); @@ -2456,14 +2480,23 @@ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) if (c->page) flush_slab(s, c); - unfreeze_partials(s, c); + unfreeze_partials_cpu(s, c); } +/* + * Flush cpu slab. + * + * Called from IPI handler with interrupts disabled. + */ static void flush_cpu_slab(void *d) { struct kmem_cache *s = d; + struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab); - __flush_cpu_slab(s, smp_processor_id()); + if (c->page) + flush_slab(s, c); + + unfreeze_partials(s); } static bool has_cpu_slab(int cpu, void *info) -- 2.31.1