From patchwork Wed Apr 14 13:39:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mel Gorman X-Patchwork-Id: 421427 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_NONE, 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 8ECB1C43603 for ; Wed, 14 Apr 2021 13:41:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6FCE9611EE for ; Wed, 14 Apr 2021 13:41:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351541AbhDNNl1 (ORCPT ); Wed, 14 Apr 2021 09:41:27 -0400 Received: from outbound-smtp21.blacknight.com ([81.17.249.41]:34067 "EHLO outbound-smtp21.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351537AbhDNNl0 (ORCPT ); Wed, 14 Apr 2021 09:41:26 -0400 Received: from mail.blacknight.com (pemlinmail01.blacknight.ie [81.17.254.10]) by outbound-smtp21.blacknight.com (Postfix) with ESMTPS id 8BF18CCE80 for ; Wed, 14 Apr 2021 14:41:03 +0100 (IST) Received: (qmail 31678 invoked from network); 14 Apr 2021 13:41:03 -0000 Received: from unknown (HELO stampy.112glenside.lan) (mgorman@techsingularity.net@[84.203.22.4]) by 81.17.254.9 with ESMTPA; 14 Apr 2021 13:41:03 -0000 From: Mel Gorman To: Linux-MM , Linux-RT-Users Cc: LKML , Chuck Lever , Jesper Dangaard Brouer , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Michal Hocko , Vlastimil Babka , Mel Gorman Subject: [PATCH 08/11] mm/page_alloc: Explicitly acquire the zone lock in __free_pages_ok Date: Wed, 14 Apr 2021 14:39:28 +0100 Message-Id: <20210414133931.4555-9-mgorman@techsingularity.net> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210414133931.4555-1-mgorman@techsingularity.net> References: <20210414133931.4555-1-mgorman@techsingularity.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org __free_pages_ok() disables IRQs before calling a common helper free_one_page() that acquires the zone lock. This is not safe according to Documentation/locking/locktypes.rst and in this context, IRQ disabling is not protecting a per_cpu_pages structure either or a local_lock would be used. This patch explicitly acquires the lock with spin_lock_irqsave instead of relying on a helper. This removes the last instance of local_irq_save() in page_alloc.c. Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka --- mm/page_alloc.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1ed370668e7f..6791e9361076 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1559,21 +1559,18 @@ static void __free_pages_ok(struct page *page, unsigned int order, unsigned long flags; int migratetype; unsigned long pfn = page_to_pfn(page); + struct zone *zone = page_zone(page); if (!free_pages_prepare(page, order, true)) return; migratetype = get_pfnblock_migratetype(page, pfn); - /* - * TODO FIX: Disable IRQs before acquiring IRQ-safe zone->lock - * and protect vmstat updates. - */ - local_irq_save(flags); + spin_lock_irqsave(&zone->lock, flags); __count_vm_events(PGFREE, 1 << order); - free_one_page(page_zone(page), page, pfn, order, migratetype, - fpi_flags); - local_irq_restore(flags); + migratetype = check_migratetype_isolated(zone, page, pfn, migratetype); + __free_one_page(page, pfn, zone, order, migratetype, fpi_flags); + spin_unlock_irqrestore(&zone->lock, flags); } void __free_pages_core(struct page *page, unsigned int order)