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=-15.8 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 autolearn=unavailable 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 96F6CC433FE for ; Wed, 8 Sep 2021 02:54:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C90E6112F for ; Wed, 8 Sep 2021 02:54:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347433AbhIHCzO (ORCPT ); Tue, 7 Sep 2021 22:55:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:51092 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347430AbhIHCzI (ORCPT ); Tue, 7 Sep 2021 22:55:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EF11D60EE6; Wed, 8 Sep 2021 02:54:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1631069641; bh=M1Y3Kn/BGFdjWwwY3wYP7/igdPipi9BBIOStfZqg2EM=; h=Date:From:To:Subject:In-Reply-To:From; b=mBbMv8nYM4jTfXD97Rrj+ef7ojzA7BGSknfm2nnbuQpEH7ZlnZ2gKx8EJ4frA3bOL ciBx43IC+KIBPZx9Oj8s/VYoz7XQMZLaXfDgzwVa4QidQqj8RYcM4MBFjGOOS9fmTK pKT1c0rRh1vTZiHiD4N/EChbArb39+Q0Y+gg6AQQ= Date: Tue, 07 Sep 2021 19:54:00 -0700 From: Andrew Morton To: akpm@linux-foundation.org, bigeasy@linutronix.de, brouer@redhat.com, cl@linux.com, efault@gmx.de, iamjoonsoo.kim@lge.com, jannh@google.com, linux-mm@kvack.org, mgorman@techsingularity.net, mm-commits@vger.kernel.org, penberg@kernel.org, quic_qiancai@quicinc.com, rientjes@google.com, tglx@linutronix.de, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 020/147] mm, slub: call deactivate_slab() without disabling irqs Message-ID: <20210908025400.5Ipep5-jZ%akpm@linux-foundation.org> In-Reply-To: <20210907195226.14b1d22a07c085b22968b933@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Vlastimil Babka Subject: mm, slub: call deactivate_slab() without disabling irqs The function is now safe to be called with irqs enabled, so move the calls outside of irq disabled sections. When called from ___slab_alloc() -> flush_slab() we have irqs disabled, so to reenable them before deactivate_slab() we need to open-code flush_slab() in ___slab_alloc() and reenable irqs after modifying the kmem_cache_cpu fields. But that means a IRQ handler meanwhile might have assigned a new page to kmem_cache_cpu.page so we have to retry the whole check. The remaining callers of flush_slab() are the IPI handler which has disabled irqs anyway, and slub_cpu_dead() which will be dealt with in the following patch. Link: https://lkml.kernel.org/r/20210904105003.11688-21-vbabka@suse.cz Signed-off-by: Vlastimil Babka Cc: Christoph Lameter Cc: David Rientjes Cc: Jann Horn Cc: Jesper Dangaard Brouer Cc: Joonsoo Kim Cc: Mel Gorman Cc: Mike Galbraith Cc: Pekka Enberg Cc: Qian Cai Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- mm/slub.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) --- a/mm/slub.c~mm-slub-call-deactivate_slab-without-disabling-irqs +++ a/mm/slub.c @@ -2779,8 +2779,8 @@ deactivate_slab: freelist = c->freelist; c->page = NULL; c->freelist = NULL; - deactivate_slab(s, page, freelist); local_irq_restore(flags); + deactivate_slab(s, page, freelist); new_slab: @@ -2848,18 +2848,32 @@ check_new_page: */ goto return_single; +retry_load_page: + local_irq_save(flags); - if (unlikely(c->page)) - flush_slab(s, c); + if (unlikely(c->page)) { + void *flush_freelist = c->freelist; + struct page *flush_page = c->page; + + c->page = NULL; + c->freelist = NULL; + c->tid = next_tid(c->tid); + + local_irq_restore(flags); + + deactivate_slab(s, flush_page, flush_freelist); + + stat(s, CPUSLAB_FLUSH); + + goto retry_load_page; + } c->page = page; goto load_freelist; return_single: - local_irq_save(flags); deactivate_slab(s, page, get_freepointer(s, freelist)); - local_irq_restore(flags); return freelist; } _