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=-7.1 required=3.0 tests=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_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 34DAAC433DF for ; Tue, 30 Jun 2020 14:27:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B14A20672 for ; Tue, 30 Jun 2020 14:27:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bHW2j8xh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727046AbgF3O1G (ORCPT ); Tue, 30 Jun 2020 10:27:06 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:49836 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388857AbgF3O06 (ORCPT ); Tue, 30 Jun 2020 10:26:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593527217; 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=DD/rc1Xq/7AFf3CzfRhrLC3+mqCELzrH74lJa/R5O94=; b=bHW2j8xh3DMIPW1ONnwpSfaFgLJ10JqIFE23SuqIoBzET8w1f+ksOEvRFN4Q3CfPx/J3aw S4mlJsAgkLX8ZYzSjFXAiNR6DeWNSKlKdwMyAvAytpjadaTbfXCI7Gej0Zdv3Zrfi1u6sf WaW9VnzWF162URrxJvjD1fYXOc8WgoQ= 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-105-I3xTV2D-Pi2Lsh1s8osUNg-1; Tue, 30 Jun 2020 10:26:53 -0400 X-MC-Unique: I3xTV2D-Pi2Lsh1s8osUNg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1EB841005513; Tue, 30 Jun 2020 14:26:52 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-56.ams2.redhat.com [10.36.114.56]) by smtp.corp.redhat.com (Postfix) with ESMTP id 94C1119C4F; Tue, 30 Jun 2020 14:26:50 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: virtualization@lists.linux-foundation.org, linux-mm@kvack.org, David Hildenbrand , Andrew Morton , Michal Hocko , "Michael S . Tsirkin" Subject: [PATCH v1 2/6] mm/page_isolation: don't dump_page(NULL) in set_migratetype_isolate() Date: Tue, 30 Jun 2020 16:26:35 +0200 Message-Id: <20200630142639.22770-3-david@redhat.com> In-Reply-To: <20200630142639.22770-1-david@redhat.com> References: <20200630142639.22770-1-david@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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. Cc: Andrew Morton Cc: Michal Hocko Cc: Michael S. Tsirkin Signed-off-by: David Hildenbrand --- mm/page_isolation.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index f6d07c5f0d34d..553b49a34cf71 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. -- 2.26.2