From nobody Sat Feb 7 21:15:32 2026 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 003B1EB64D9 for ; Wed, 14 Jun 2023 11:04:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243632AbjFNLEA (ORCPT ); Wed, 14 Jun 2023 07:04:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236214AbjFNLDo (ORCPT ); Wed, 14 Jun 2023 07:03:44 -0400 Received: from out-62.mta1.migadu.com (out-62.mta1.migadu.com [95.215.58.62]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8069A1BE5 for ; Wed, 14 Jun 2023 04:03:42 -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=1686740617; 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; bh=JUAXO3nF4TYUh7G4bGQ31E/7+rub4uhiLNTBrM2ujC8=; b=P06EKQSYiSzPJZCUwYNF5LhDGDRkWumiodO74KPIgoDsJrSSb2UrF6A7dqnDxkcI4mWLjI nb9+BJDG2syeWPi7IUgLgHswlfW/eBUTP6IOeABhyIBQQry9VGuTvpKhY+7YUZVYrZN8jH k9zNpZiJ+8Ve3g+BfGPpBFZezTn8LhM= From: Yajun Deng To: gregkh@linuxfoundation.org, rafael@kernel.org, rppt@kernel.org, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Yajun Deng Subject: [PATCH] mm/mm_init.c: remove spinlock in early_pfn_to_nid() Date: Wed, 14 Jun 2023 19:03:24 +0800 Message-Id: <20230614110324.3839354-1-yajun.deng@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" When the system boots, only one cpu is enabled before smp_init(). So the spinlock is not needed in most cases, remove it. Add spinlock in get_nid_for_pfn() because it is after smp_init(). Signed-off-by: Yajun Deng --- drivers/base/node.c | 11 +++++++++-- mm/mm_init.c | 18 +++--------------- 2 files changed, 12 insertions(+), 17 deletions(-) diff --git a/drivers/base/node.c b/drivers/base/node.c index 9de524e56307..844102570ff2 100644 --- a/drivers/base/node.c +++ b/drivers/base/node.c @@ -748,8 +748,15 @@ int unregister_cpu_under_node(unsigned int cpu, unsign= ed int nid) static int __ref get_nid_for_pfn(unsigned long pfn) { #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT - if (system_state < SYSTEM_RUNNING) - return early_pfn_to_nid(pfn); + static DEFINE_SPINLOCK(early_pfn_lock); + int nid; + + if (system_state < SYSTEM_RUNNING) { + spin_lock(&early_pfn_lock); + nid =3D early_pfn_to_nid(pfn); + spin_unlock(&early_pfn_lock); + return nid; + } #endif return pfn_to_nid(pfn); } diff --git a/mm/mm_init.c b/mm/mm_init.c index d393631599a7..5895a30435ee 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -584,11 +584,11 @@ struct mminit_pfnnid_cache { static struct mminit_pfnnid_cache early_pfnnid_cache __meminitdata; =20 /* - * Required by SPARSEMEM. Given a PFN, return what node the PFN is on. + * Given a PFN, return what node the PFN is on. */ -static int __meminit __early_pfn_to_nid(unsigned long pfn, - struct mminit_pfnnid_cache *state) +int __meminit early_pfn_to_nid(unsigned long pfn) { + struct mminit_pfnnid_cache *state =3D &early_pfnnid_cache; unsigned long start_pfn, end_pfn; int nid; =20 @@ -601,20 +601,8 @@ static int __meminit __early_pfn_to_nid(unsigned long = pfn, state->last_end =3D end_pfn; state->last_nid =3D nid; } - - return nid; -} - -int __meminit early_pfn_to_nid(unsigned long pfn) -{ - static DEFINE_SPINLOCK(early_pfn_lock); - int nid; - - spin_lock(&early_pfn_lock); - nid =3D __early_pfn_to_nid(pfn, &early_pfnnid_cache); if (nid < 0) nid =3D first_online_node; - spin_unlock(&early_pfn_lock); =20 return nid; } --=20 2.25.1