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=-8.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLACK,URIBL_BLOCKED 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 6B593C433DF for ; Thu, 30 Jul 2020 09:34:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4D00120838 for ; Thu, 30 Jul 2020 09:34:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Ozlcc2r+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729352AbgG3Jeo (ORCPT ); Thu, 30 Jul 2020 05:34:44 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:45709 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726774AbgG3Jeo (ORCPT ); Thu, 30 Jul 2020 05:34:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1596101683; 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: in-reply-to:in-reply-to:references:references; bh=dyDrSr/R3IYIedmMJp2EbzPQ1RIZu9oQIJgsVrWfxkI=; b=Ozlcc2r+/Rpb1LG8ZQEISXtF0JT6KZnslzKziUm2hIRu1Vkq6yiDWhBNdCHqjshjax133N 7H/onwd3mH1ZG8ZCdNv9FNAcZnhki/YWqkOIDkHZgouue/salNv+URKwNWhPyu1+5q2AzI hU6jmB45SpFrvVCVWU3HHOzr8ZaSzhs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-320-lDLuFZxMNhyGsrVpnuPohw-1; Thu, 30 Jul 2020 05:34:41 -0400 X-MC-Unique: lDLuFZxMNhyGsrVpnuPohw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 93EC981F3DF; Thu, 30 Jul 2020 09:34:22 +0000 (UTC) Received: from t480s.redhat.com (ovpn-113-185.ams2.redhat.com [10.36.113.185]) by smtp.corp.redhat.com (Postfix) with ESMTP id 63E875FC31; Thu, 30 Jul 2020 09:34:20 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: virtualization@lists.linux-foundation.org, linux-mm@kvack.org, David Hildenbrand , Baoquan He , Pankaj Gupta , Mike Kravetz , Andrew Morton , Michal Hocko , "Michael S . Tsirkin" , Qian Cai Subject: [PATCH v2 1/6] mm/page_isolation: don't dump_page(NULL) in set_migratetype_isolate() Date: Thu, 30 Jul 2020 11:34:11 +0200 Message-Id: <20200730093416.36210-2-david@redhat.com> In-Reply-To: <20200730093416.36210-1-david@redhat.com> References: <20200730093416.36210-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Right now, if we have two isolations racing, we might trigger the WARN_ON_ONCE() and to dump_page(NULL), dereferencing NULL. Let's just return directly. In the future, we might want to report -EAGAIN to the caller instead, as this could indicate a temporary isolation failure only. Reviewed-by: Baoquan He Reviewed-by: Pankaj Gupta Acked-by: Mike Kravetz Fixes: 4a55c0474a92 ("mm/hotplug: silence a lockdep splat with printk()") Cc: Andrew Morton Cc: Michal Hocko Cc: Michael S. Tsirkin Cc: Qian Cai Signed-off-by: David Hildenbrand --- mm/page_isolation.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index f6d07c5f0d34d..7d7d263ce7f4b 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -29,10 +29,12 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ /* * We assume the caller intended to SET migrate type to isolate. * If it is already set, then someone else must have raced and - * set it before us. Return -EBUSY + * set it before us. */ - if (is_migrate_isolate_page(page)) - goto out; + if (is_migrate_isolate_page(page)) { + spin_unlock_irqrestore(&zone->lock, flags); + return -EBUSY; + } /* * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. @@ -52,7 +54,6 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ ret = 0; } -out: spin_unlock_irqrestore(&zone->lock, flags); if (!ret) { drain_all_pages(zone); -- 2.26.2