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 3EE00C433E1 for ; Thu, 30 Jul 2020 04:21:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EE2B22070B for ; Thu, 30 Jul 2020 04:21:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PZg3x3E9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EE2B22070B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 65ECC6B0005; Thu, 30 Jul 2020 00:21:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 60FA16B0008; Thu, 30 Jul 2020 00:21:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 527DF6B000A; Thu, 30 Jul 2020 00:21:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0018.hostedemail.com [216.40.44.18]) by kanga.kvack.org (Postfix) with ESMTP id 443636B0005 for ; Thu, 30 Jul 2020 00:21:46 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id DEB6D824934B for ; Thu, 30 Jul 2020 04:21:45 +0000 (UTC) X-FDA: 77093443770.21.table24_2c0fe5126f78 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id AB59B180442C7 for ; Thu, 30 Jul 2020 04:21:45 +0000 (UTC) X-HE-Tag: table24_2c0fe5126f78 X-Filterd-Recvd-Size: 4317 Received: from mail-io1-f68.google.com (mail-io1-f68.google.com [209.85.166.68]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Thu, 30 Jul 2020 04:21:45 +0000 (UTC) Received: by mail-io1-f68.google.com with SMTP id t15so17987633iob.3 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=LukprkKA0oxXokkPRkOImvK7icpVBM3KMMmMGIR/O+HtD2GarlUw0L79j6A2afuK/I 5FRqSC6W21CEBMOOR3IR8ZT0/AqaSQyLSel/PTuMymNE9tfVzTFpF7cjgjuO7B3We7oa TsmsFPP4ZDjqN/O5WJ/ioZjbC4Tu81yEN5XddceOoJJxZURZrh6tk5/MULzhZEvCvk2k DqYXHx4h1oHOXD8SWPyJPiCbgYoDHGdcJDaYh+eaRB+oCJMaYFMEC/cLOgsgl32A//wj ZeYQZUZoZQihRVZypHvd5BdLb+2K4q086h76t4JDfNs6YjZYNB8myOvTLouGl/BYPTSx 9gXg== X-Gm-Message-State: AOAM531WkfD2pyzqEAqymK1XfCaX23UHaPPO2kajUqS1yqobVWoXE7QK 8SG/seFuYwnepsLX4DGab5Nh2xSKWOh8EY3m9HQ= 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" X-Rspamd-Queue-Id: AB59B180442C7 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > 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 > >