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[64.147.123.25]) by mx.google.com with ESMTPS id m14si3485264qtp.177.2019.02.01.06.09.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 01 Feb 2019 06:09:26 -0800 (PST) Received-SPF: pass (google.com: domain of greg@kroah.com designates 64.147.123.25 as permitted sender) client-ip=64.147.123.25; Authentication-Results: mx.google.com; dkim=pass header.i=@kroah.com header.s=fm2 header.b=IUEd3GXJ; dkim=pass header.i=@messagingengine.com header.s=fm1 header.b=FJFoK3yA; spf=pass (google.com: domain of greg@kroah.com designates 64.147.123.25 as permitted sender) smtp.mailfrom=greg@kroah.com Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id 758341264; Fri, 1 Feb 2019 09:09:24 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Fri, 01 Feb 2019 09:09:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm2; bh=kh208pwU0DHoRepH3JHwazRnR9a 3aEF0XNjNIFI4NjA=; b=IUEd3GXJ/k9uKEYr9LBZgsZ0CK3QCHH6E0bAlrLug4V ONOc8A2erGaRLWPCFD61ES47CdlOxsNp2139AJueSzyuTDnsbJH+Gl6YPcCuJzYx lQGE4qphnifqpg90s+avv+Knp5nDU2+dRPlzv3ariLgi38piOvpdbsmUliGdeU1m erCQJ9S7fHWf7HfO9aUj/N8fXszn6fublaQ+9OJEoICJfKQojQrz+nNeI4URIpaW Zp45TCqZ2b7k97ghHG4vQbJ5XPPdOUD3gWz67p/o3cpl9Igljv141Iw9+idhIiJZ dytIFgpUWwUz1jzTBBX0S1yRnzFzn7L5C+SHkbMFMPg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; bh=kh208p wU0DHoRepH3JHwazRnR9a3aEF0XNjNIFI4NjA=; b=FJFoK3yAAMjwlkttwou4Dc 1oogG0GB1/z8YnahCoTASp98yDDpNsNECDPwOKKiUgV9a4SdrNwywMK3x/CenSC4 CTsrsxyRd4Ule+57VsdXZrcnv8R5doD2NIny4ZzMXFC9jYoQeRk7VuEOVA1tTXd9 Mp2rqdeOEwlRrxEE/rX9FWLnUnsIVulKOFiRPaf4ub1Fr9JuPKS56HQ2DSdefR5j avnxFqK1i57tbgeYQp4AbASCNBK4zIz8jnKVlPLSzcizm6HATSn1QkxjHTxXXFSe rQkdv2Z6bswQFAd3JnH9AC3x+Rpc0Q/pdTnzr849v7s8HMP/drt1IhaK2r99aPqQ == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedtledrjeekgdeiudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfhuthenuceurghilhhouhhtmecufedt tdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepfffhvffukfhfgg gtuggjfgesthdtredttdervdenucfhrhhomhepifhrvghgucfmjfcuoehgrhgvgheskhhr ohgrhhdrtghomheqnecukfhppeekfedrkeeirdekledruddtjeenucfrrghrrghmpehmrg hilhhfrhhomhepghhrvghgsehkrhhorghhrdgtohhmnecuvehluhhsthgvrhfuihiivgep td X-ME-Proxy: Received: from localhost (5356596b.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) by mail.messagingengine.com (Postfix) with ESMTPA id 51872E409D; Fri, 1 Feb 2019 09:09:20 -0500 (EST) Date: Fri, 1 Feb 2019 15:09:18 +0100 From: Greg KH To: David Hildenbrand Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Mel Gorman , "Kirill A. Shutemov" , Michal Hocko , Naoya Horiguchi , Jan Kara , Andrea Arcangeli , Dominik Brodowski , Matthew Wilcox , Vratislav Bendel , Rafael Aquini , Konstantin Khlebnikov , Minchan Kim , Sasha Levin , stable@vger.kernel.org Subject: Re: [PATCH v2 for-4.4-stable] mm: migrate: don't rely on __PageMovable() of newpage after unlocking it Message-ID: <20190201140918.GB20335@kroah.com> References: <20190131020448.072FE218AF@mail.kernel.org> <20190201134347.11166-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190201134347.11166-1-david@redhat.com> User-Agent: Mutt/1.11.2 (2019-01-07) 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: On Fri, Feb 01, 2019 at 02:43:47PM +0100, David Hildenbrand wrote: > This is the backport for 4.4-stable. > > We had a race in the old balloon compaction code before commit b1123ea6d3b3 > ("mm: balloon: use general non-lru movable page feature") refactored it > that became visible after backporting commit 195a8c43e93d > ("virtio-balloon: deflate via a page list") without the refactoring. > > The bug existed from commit d6d86c0a7f8d ("mm/balloon_compaction: redesign > ballooned pages management") till commit b1123ea6d3b3 ("mm: balloon: use > general non-lru movable page feature"). commit d6d86c0a7f8d > ("mm/balloon_compaction: redesign ballooned pages management") was > backported to 3.12, so the broken kernels are stable kernels [3.12 - 4.7]. > > There was a subtle race between dropping the page lock of the newpage > in __unmap_and_move() and checking for > __is_movable_balloon_page(newpage). > > Just after dropping this page lock, virtio-balloon could go ahead and > deflate the newpage, effectively dequeueing it and clearing PageBalloon, > in turn making __is_movable_balloon_page(newpage) fail. > > This resulted in dropping the reference of the newpage via > putback_lru_page(newpage) instead of put_page(newpage), leading to > page->lru getting modified and a !LRU page ending up in the LRU lists. > With commit 195a8c43e93d ("virtio-balloon: deflate via a page list") > backported, one would suddenly get corrupted lists in > release_pages_balloon(): > - WARNING: CPU: 13 PID: 6586 at lib/list_debug.c:59 __list_del_entry+0xa1/0xd0 > - list_del corruption. prev->next should be ffffe253961090a0, but was dead000000000100 > > Nowadays this race is no longer possible, but it is hidden behind very > ugly handling of __ClearPageMovable() and __PageMovable(). > > __ClearPageMovable() will not make __PageMovable() fail, only > PageMovable(). So the new check (__PageMovable(newpage)) will still hold > even after newpage was dequeued by virtio-balloon. > > If anybody would ever change that special handling, the BUG would be > introduced again. So instead, make it explicit and use the information > of the original isolated page before migration. > > This patch can be backported fairly easy to stable kernels (in contrast > to the refactoring). > > Cc: Andrew Morton > Cc: Mel Gorman > Cc: "Kirill A. Shutemov" > Cc: Michal Hocko > Cc: Naoya Horiguchi > Cc: Jan Kara > Cc: Andrea Arcangeli > Cc: Dominik Brodowski > Cc: Matthew Wilcox > Cc: Vratislav Bendel > Cc: Rafael Aquini > Cc: Konstantin Khlebnikov > Cc: Minchan Kim > Cc: Sasha Levin > Cc: stable@vger.kernel.org # 3.12 - 4.7 > Fixes: d6d86c0a7f8d ("mm/balloon_compaction: redesign ballooned pages management") > Reported-by: Vratislav Bendel > Acked-by: Michal Hocko > Acked-by: Rafael Aquini > Signed-off-by: David Hildenbrand > --- > mm/migrate.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) What is the git commit id of this patch in Linus's tree? thanks, greg k-h