From patchwork Sat Sep 4 10:49:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 12475537 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 A7CDBC433F5 for ; Sat, 4 Sep 2021 10:51:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 651EC600D4 for ; Sat, 4 Sep 2021 10:51:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 651EC600D4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 3D512940009; Sat, 4 Sep 2021 06:50:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E377590000B; Sat, 4 Sep 2021 06:50:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 72B58900007; Sat, 4 Sep 2021 06:50:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0174.hostedemail.com [216.40.44.174]) by kanga.kvack.org (Postfix) with ESMTP id E575B6B0083 for ; Sat, 4 Sep 2021 06:50:15 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 91F6B8248076 for ; Sat, 4 Sep 2021 10:50:15 +0000 (UTC) X-FDA: 78549571590.18.9959A96 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf06.hostedemail.com (Postfix) with ESMTP id 433E9801A88D for ; Sat, 4 Sep 2021 10:50:15 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 49E762004C; Sat, 4 Sep 2021 10:50:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1630752614; 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=+ROWetETu9kRdMbomd37GMTie//m23OlCu21sQBbUl4=; b=F7GZaVepbAM+TaN/8QnZqT7ojUaN4DfohYbRx507liBEjAD1wSixZV9eXLtaM81OJydBZm sYcJ9XjHuhKELTC83QzlYZKcGjTzfT6xm4uJZQBXqzqIkQndemBGZSLBsF/+fW12MJCpUH YctcHZP6Lj9a5HsK4JbNvb71A7pOOmA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1630752614; 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=+ROWetETu9kRdMbomd37GMTie//m23OlCu21sQBbUl4=; b=kuRLw8aI69OvF3SzP26y7KcJja1NkUyfAkYPQm/+nGLBZ6X+3gzUiQsPcD6PuX4H9y7jTg 3oLiEJab0FxLNOAQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 226571348A; Sat, 4 Sep 2021 10:50:14 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id CIjHB2ZPM2HoUQAAMHmgww (envelope-from ); Sat, 04 Sep 2021 10:50:14 +0000 From: Vlastimil Babka To: linux-mm@kvack.org, Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: Andrew Morton , linux-kernel@vger.kernel.org, Mike Galbraith , Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Vlastimil Babka Subject: [PATCH v6 28/33] mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context Date: Sat, 4 Sep 2021 12:49:58 +0200 Message-Id: <20210904105003.11688-29-vbabka@suse.cz> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210904105003.11688-1-vbabka@suse.cz> References: <20210904105003.11688-1-vbabka@suse.cz> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5641; i=vbabka@suse.cz; h=from:subject; bh=RFyIAg8pO6Wlp9YLx1y4SOJmK0WVFwSTEu0I5PRQaUA=; b=owEBbQGS/pANAwAIAeAhynPxiakQAcsmYgBhM09MEhT0P/nYHovK3rOS2tiLVpbZWYBqvRPytExV DFXvXWeJATMEAAEIAB0WIQSNS5MBqTXjGL5IXszgIcpz8YmpEAUCYTNPTAAKCRDgIcpz8YmpELBBCA CIg3yCkqtzzAiCk4qS8+LUevzu4nfcRtrkKZmnIQUCh+I3RX57jjVWwYQnY5NOvopa7fKibspPUJa9 hMyHTQPo/vy6zLHPaO9vhg3Rue44fJ7+27q0keWX+IqHfT5upseoQWJAAoHz3jQEjyGOAfNCjsoqZZ 3zu4V8oAJbmJkHLG0WPVRnNQRgXcqd/djNfErKW/eLSYaYw4ND43XwCuQE0E9muyfa7nKUP5k1BZrw RkWVZvnDF5pyTyHXOEWrrXGiZFlyDka/yEdzlSiY373w/IkItNb7aoSHhYah/41P2M44vh0Y4Bixql PTwawvjA2KgarHIfDRDq2xU4LqRCP9 X-Developer-Key: i=vbabka@suse.cz; a=openpgp; fpr=A940D434992C2E8E99103D50224FA7E7CC82A664 X-Rspamd-Queue-Id: 433E9801A88D Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=F7GZaVep; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=kuRLw8aI; dmarc=none; spf=pass (imf06.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam01 X-Stat-Signature: jp7xmnds9yspw69k8di96n847qh5zjrs X-HE-Tag: 1630752615-634794 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Sebastian Andrzej Siewior flush_all() flushes a specific SLAB cache on each CPU (where the cache is present). The deactivate_slab()/__free_slab() invocation happens within IPI handler and is problematic for PREEMPT_RT. The flush operation is not a frequent operation or a hot path. The per-CPU flush operation can be moved to within a workqueue. Because a workqueue handler, unlike IPI handler, does not disable irqs, flush_slab() now has to disable them for working with the kmem_cache_cpu fields. deactivate_slab() is safe to call with irqs enabled. [vbabka@suse.cz: adapt to new SLUB changes] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Vlastimil Babka --- mm/slab_common.c | 2 ++ mm/slub.c | 94 +++++++++++++++++++++++++++++++++++++++--------- 2 files changed, 80 insertions(+), 16 deletions(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index 1c673c323baf..ec2bb0beed75 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -502,6 +502,7 @@ void kmem_cache_destroy(struct kmem_cache *s) if (unlikely(!s)) return; + cpus_read_lock(); mutex_lock(&slab_mutex); s->refcount--; @@ -516,6 +517,7 @@ void kmem_cache_destroy(struct kmem_cache *s) } out_unlock: mutex_unlock(&slab_mutex); + cpus_read_unlock(); } EXPORT_SYMBOL(kmem_cache_destroy); diff --git a/mm/slub.c b/mm/slub.c index fa9a366d2d9c..b7f8b9d34e46 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2496,16 +2496,25 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) { - void *freelist = c->freelist; - struct page *page = c->page; + unsigned long flags; + struct page *page; + void *freelist; + + local_irq_save(flags); + + page = c->page; + freelist = c->freelist; c->page = NULL; c->freelist = NULL; c->tid = next_tid(c->tid); - deactivate_slab(s, page, freelist); + local_irq_restore(flags); - stat(s, CPUSLAB_FLUSH); + if (page) { + deactivate_slab(s, page, freelist); + stat(s, CPUSLAB_FLUSH); + } } static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) @@ -2526,15 +2535,27 @@ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) unfreeze_partials_cpu(s, c); } +struct slub_flush_work { + struct work_struct work; + struct kmem_cache *s; + bool skip; +}; + /* * Flush cpu slab. * - * Called from IPI handler with interrupts disabled. + * Called from CPU work handler with migration disabled. */ -static void flush_cpu_slab(void *d) +static void flush_cpu_slab(struct work_struct *w) { - struct kmem_cache *s = d; - struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab); + struct kmem_cache *s; + struct kmem_cache_cpu *c; + struct slub_flush_work *sfw; + + sfw = container_of(w, struct slub_flush_work, work); + + s = sfw->s; + c = this_cpu_ptr(s->cpu_slab); if (c->page) flush_slab(s, c); @@ -2542,17 +2563,51 @@ static void flush_cpu_slab(void *d) unfreeze_partials(s); } -static bool has_cpu_slab(int cpu, void *info) +static bool has_cpu_slab(int cpu, struct kmem_cache *s) { - struct kmem_cache *s = info; struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); return c->page || slub_percpu_partial(c); } +static DEFINE_MUTEX(flush_lock); +static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); + +static void flush_all_cpus_locked(struct kmem_cache *s) +{ + struct slub_flush_work *sfw; + unsigned int cpu; + + lockdep_assert_cpus_held(); + mutex_lock(&flush_lock); + + for_each_online_cpu(cpu) { + sfw = &per_cpu(slub_flush, cpu); + if (!has_cpu_slab(cpu, s)) { + sfw->skip = true; + continue; + } + INIT_WORK(&sfw->work, flush_cpu_slab); + sfw->skip = false; + sfw->s = s; + schedule_work_on(cpu, &sfw->work); + } + + for_each_online_cpu(cpu) { + sfw = &per_cpu(slub_flush, cpu); + if (sfw->skip) + continue; + flush_work(&sfw->work); + } + + mutex_unlock(&flush_lock); +} + static void flush_all(struct kmem_cache *s) { - on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1); + cpus_read_lock(); + flush_all_cpus_locked(s); + cpus_read_unlock(); } /* @@ -4097,7 +4152,7 @@ int __kmem_cache_shutdown(struct kmem_cache *s) int node; struct kmem_cache_node *n; - flush_all(s); + flush_all_cpus_locked(s); /* Attempt to free all objects */ for_each_kmem_cache_node(s, node, n) { free_partial(s, n); @@ -4373,7 +4428,7 @@ EXPORT_SYMBOL(kfree); * being allocated from last increasing the chance that the last objects * are freed in them. */ -int __kmem_cache_shrink(struct kmem_cache *s) +static int __kmem_cache_do_shrink(struct kmem_cache *s) { int node; int i; @@ -4385,7 +4440,6 @@ int __kmem_cache_shrink(struct kmem_cache *s) unsigned long flags; int ret = 0; - flush_all(s); for_each_kmem_cache_node(s, node, n) { INIT_LIST_HEAD(&discard); for (i = 0; i < SHRINK_PROMOTE_MAX; i++) @@ -4435,13 +4489,21 @@ int __kmem_cache_shrink(struct kmem_cache *s) return ret; } +int __kmem_cache_shrink(struct kmem_cache *s) +{ + flush_all(s); + return __kmem_cache_do_shrink(s); +} + static int slab_mem_going_offline_callback(void *arg) { struct kmem_cache *s; mutex_lock(&slab_mutex); - list_for_each_entry(s, &slab_caches, list) - __kmem_cache_shrink(s); + list_for_each_entry(s, &slab_caches, list) { + flush_all_cpus_locked(s); + __kmem_cache_do_shrink(s); + } mutex_unlock(&slab_mutex); return 0;