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=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 3594DC433E0 for ; Thu, 30 Jul 2020 04:21:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 053D222B43 for ; Thu, 30 Jul 2020 04:21:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PZg3x3E9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728070AbgG3EVp (ORCPT ); Thu, 30 Jul 2020 00:21:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725765AbgG3EVp (ORCPT ); Thu, 30 Jul 2020 00:21:45 -0400 Received: from mail-io1-xd41.google.com (mail-io1-xd41.google.com [IPv6:2607:f8b0:4864:20::d41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 400FFC061794 for ; Wed, 29 Jul 2020 21:21:45 -0700 (PDT) Received: by mail-io1-xd41.google.com with SMTP id k23so26872278iom.10 for ; Wed, 29 Jul 2020 21:21:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=6xpfl3EgxCfkX2czZsyELOLTTm2Qpx8o0HHjudwK3iQ=; b=PZg3x3E96FLpVfIP4mXsw6BJZa4kPE724pl4xDKJ762RhlwGzZDB/XJH0kA7tI9NJk 0ueTo6zqLNzsEUaORTov6c7u0Uq/ToqZ8Yea7HoEB9fpHbs/5BM2hiimDiS/9POw6Kf6 oFw7JsCzJJjkwiLmiwwtgXzBOmuELSmpECDPP/7dipETJB4Wg58tR6d2cJU+uCEFRDQ5 WG/zSQGPATkSf89kIXWxTZPldDV3JuLOJ5SrLl53a//S0Fp3w35L6VmWkMFf0mnQJQtz +CL/hxthboihNtBZXjHk4nzk4xKqvGnGejHab4KdvUR9nom+ka59A8bDCT6GuoLdEo/+ PVWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=6xpfl3EgxCfkX2czZsyELOLTTm2Qpx8o0HHjudwK3iQ=; b=Lkk7+C6sUGvhLGIjb0t/vlR9x542xbcjE5xfPhC2R3ZtdF/VWu73uArUpGSdCk5Xcr 4hrlxg6km+c6V83/ZlmD01Fj3WSk2cNOQJnAP8crXG+6+J9KaSpvBYVD7rHJoDCoVqES 8yXpUIKwv83+hO/8qrB/APfpNDR+ueG3XisbBzDYZaoAW2rwGCIMAIQJJVnRij4XUVxA O7ZlhwBInUgmizfU8CFP6KYZRqnQdpt65+0T30Vio53dtbdjikOfjsvdINZ+e/WkUtfC nViMdnAEiO+HYLrTbNyNruMM2iaZ9kME0B6aHe5YigTIz6JIGCtcNAcPQCAdULkD4M5A Mp+A== X-Gm-Message-State: AOAM533mb+HzqwmgV63rDj91I96q/GdUDcqSEPCSkQvUPlI/e6HVP9on t7q3W7BDKiKFET0er4N79acgi1i6Y96qC7ZkA05v3olEftY= X-Google-Smtp-Source: ABdhPJykIKJCHIXweVbFX5NqFGgm+dgBMuMyqp12O5YWh5nSx5UmBH6/j6/5tCLa+7uUqLnQcmkw5jGVyHRRpBmNCtw= X-Received: by 2002:a02:6066:: with SMTP id d38mr1479683jaf.105.1596082904664; Wed, 29 Jul 2020 21:21:44 -0700 (PDT) MIME-Version: 1.0 References: <20200630142639.22770-1-david@redhat.com> <20200630142639.22770-3-david@redhat.com> In-Reply-To: <20200630142639.22770-3-david@redhat.com> From: Pankaj Gupta Date: Thu, 30 Jul 2020 06:21:33 +0200 Message-ID: Subject: Re: [PATCH v1 2/6] mm/page_isolation: don't dump_page(NULL) in set_migratetype_isolate() To: David Hildenbrand Cc: LKML , virtualization@lists.linux-foundation.org, Linux MM , Andrew Morton , Michal Hocko , "Michael S . Tsirkin" Content-Type: text/plain; charset="UTF-8" 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. > -- Reviewed-by: Pankaj Gupta > 2.26.2 > >