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[66.111.4.26]) by mx.google.com with ESMTPS id z31si79328qtj.27.2019.02.26.12.35.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 26 Feb 2019 12:35:53 -0800 (PST) Received-SPF: pass (google.com: domain of nikolaus@rath.org designates 66.111.4.26 as permitted sender) client-ip=66.111.4.26; Authentication-Results: mx.google.com; dkim=pass header.i=@rath.org header.s=fm1 header.b=RYg2VuhG; dkim=pass header.i=@messagingengine.com header.s=fm2 header.b=0ZychgeN; spf=pass (google.com: domain of nikolaus@rath.org designates 66.111.4.26 as permitted sender) smtp.mailfrom=Nikolaus@rath.org Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id AA6432211F; Tue, 26 Feb 2019 15:35:53 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute1.internal (MEProxy); Tue, 26 Feb 2019 15:35:53 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rath.org; h=from :to:subject:references:date:in-reply-to:message-id:mime-version :content-type:content-transfer-encoding; s=fm1; bh=SH3OtmlQYztY1 hVcAwbfBht4gbItJffosAmmOmWlCAc=; b=RYg2VuhGTo7oZkqS1+m5RH3zpvemy v16Jh+7/3yfapPeDtXjERLZlNZK6tljjWRw6eQ7YjxzpAFhB+xU5Kx2j8KWmHqbA sQ8LVQig2HRGEmQgWLImVDVz1cqDg3M4+10x71jSCkExoxinC53nQljVzQ2SK9z1 ip8wCHHcGDcq8T06Jmp4TaVaKqbu5ZmU/BQ2nZQ6XdirNLYV0qZ/0MS+MY7FVf0A gc+qMvLeUfX92Wuv9TtMueA7Jw/F1FZn1raPvWvxA/kTdNKNlEFPkWluTvQxQrYe 6HZtsR4/+tM+X7jA8oF/a+VdJky99FgRtdc/ungAHYXddZXl+uOWeQOLQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-transfer-encoding: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=fm2; bh=SH3OtmlQYztY1hVcAwbfBht4gbItJffosAmmOmWlC Ac=; b=0ZychgeNSkl/NgvqUu2ZGsDAbvyz1FsUAlzBS+qYqOOu6okVISa7tp1eg XeqK9Ka56SNUNBBZJR/eEaQUDnVQyabpT9obMzUfCmCrgpA6wiCT3yxX2Cx2U0ZS UspGjPzfzayZFNyze+F2IVFYlR/XgEEEjG4UyeZ4lPIgnqm/8wk+iqKFkjGlmYtE ILA2iIPMfF8u1usRXCMYrSZ8GdZ9leoNzzZAwjjxDaFhKO9RHziIA2y/HzumYvl1 x8WJMUM1DePn6ZI4M7l5YGr/f/b/aIwd/x8cqvyLrBLZaSpStR4Jb4Frz+aKA55a IvXEDNnRnrtzHLNpzFA+Clh3rf/FQ== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedutddrudelgddugedvucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvufhfffgjkfgfgggtgfesthhqtddttderjeenucfhrhhomheppfhikhho lhgruhhsucftrghthhcuoefpihhkohhlrghushesrhgrthhhrdhorhhgqeenucffohhmrg hinhepshhouhhrtggvfhhorhhgvgdrnhgvthenucfkphepudekhedrfedrleegrdduleeg necurfgrrhgrmhepmhgrihhlfhhrohhmpefpihhkohhlrghushesrhgrthhhrdhorhhgne cuvehluhhsthgvrhfuihiivgeptd X-ME-Proxy: Received: from ebox.rath.org (ebox.rath.org [185.3.94.194]) by mail.messagingengine.com (Postfix) with ESMTPA id 6A24310328; Tue, 26 Feb 2019 15:35:52 -0500 (EST) Received: from vostro.rath.org (vostro [192.168.12.4]) by ebox.rath.org (Postfix) with ESMTPS id 4D6C250; Tue, 26 Feb 2019 20:35:51 +0000 (UTC) Received: by vostro.rath.org (Postfix, from userid 1000) id 0EFDAE00C3; Tue, 26 Feb 2019 20:35:50 +0000 (GMT) From: Nikolaus Rath To: Miklos Szeredi , linux-mm@kvack.org Subject: Re: [fuse-devel] fuse: trying to steal weird page References: <87o998m0a7.fsf@vostro.rath.org> <87ef9omb5f.fsf@vostro.rath.org> <87ef9nighv.fsf@thinkpad.rath.org> <87zhs7fbkg.fsf@thinkpad.rath.org> <8736ovcn9q.fsf@vostro.rath.org> <877ee4vgr4.fsf@vostro.rath.org> <878sy3h7gr.fsf@vostro.rath.org> Date: Tue, 26 Feb 2019 20:35:50 +0000 In-Reply-To: (Miklos Szeredi's message of "Tue, 26 Feb 2019 14:30:01 +0100") Message-ID: <87bm2ymgnt.fsf@vostro.rath.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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: [ Moving fuse-devel and linux-fsdevel to Bcc ] Hello linux-mm people, I am posting this here as advised by Miklos (see below). In short, I have a workload that reliably produces kernel messages of the form: [ 2562.773181] fuse: trying to steal weird page [ 2562.773187] page=3D index=3D flags=3D17ffffc00000a= d, count=3D1, mapcount=3D0, mapping=3D (null) What are the implications of this message? Is something activelly going wrong (aka do I need to worry about data integrity)? Is there something I can do to help debugging (and hopefully fixing) this? This is with kernel 4.18 (from Ubuntu cosmic). Best, -Nikolaus On Feb 26 2019, Miklos Szeredi wrote: > On Tue, Feb 26, 2019 at 1:57 PM Miklos Szeredi wrote: >> >> On Mon, Feb 25, 2019 at 10:41 PM Nikolaus Rath wrote: >> > >> > On Feb 12 2019, Nikolaus Rath wrote: >> > > On Feb 12 2019, Miklos Szeredi wrote: >> > >> On Sun, Feb 10, 2019 at 11:05 PM Nikolaus Rath = wrote: >> > >> >> > >>> Bad news. I can now reliably reproduce the issue again. >> > >> >> > >> A reliable reproducer is always good news. Are the messages exact= ly >> > >> the same as last time (value of flags, etc)? >> > > >> > > The flags, count, mapcount and mapping values are always the same. T= he >> > > page and index is varying. So the general format is: >> > > >> > > [ 2562.773181] fuse: trying to steal weird page >> > > [ 2562.773187] page=3D index=3D >> > > flags=3D17ffffc00000ad, count=3D1, mapcount=3D0, mapping=3D (null) >> > >> > Is there anything else I can do to help debugging this? >> >> Could you please try the attached patch? > > Looking more, it's very unlikely to help. remove_mapping() should > already ensure that the page count is 1. > > I think this bug report needs to be forwarded to the > mailing list as this appears to be a race > somewhere in the memory management subsystem and fuse is only making > it visible due to its sanity checking in the page stealing code. > > Thanks, > Miklos > > > --=20 > fuse-devel mailing list > To unsubscribe or subscribe, visit https://lists.sourceforge.net/lists/li= stinfo/fuse-devel --=20 GPG Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F =C2=BBTime flies like an arrow, fruit flies like a Banana.=C2= =AB