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[66.111.4.26]) by mx.google.com with ESMTPS id k14si5250311qkj.20.2019.03.01.12.40.35 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 01 Mar 2019 12:40:36 -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=g94nagG6; dkim=pass header.i=@messagingengine.com header.s=fm2 header.b=1eM0302J; 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 9AC2621F2F; Fri, 1 Mar 2019 15:40:35 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute1.internal (MEProxy); Fri, 01 Mar 2019 15:40:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rath.org; h=from :to:cc:subject:references:date:in-reply-to:message-id :mime-version:content-type:content-transfer-encoding; s=fm1; bh= gaZtj5W8VUXhVGMnCQf2AvbtnTkW/jB95uYULjvMR+I=; b=g94nagG6Z6UQ4E9V UvKyn4Q9qvk7eZkj9SG+fNweP8uMIkOPphNrgb1dmiUwb1L8mWi1rm9fg2JCUgyn sWI5wMyha6DLN/AYiiiHTeCvHLSXeoqSN2T99zT8JX30iXGfm2nLRHMse4bIJvXa FtimR1BJEMuBxNxs58F0z5fAtjhXdsjtuTJ3RSXfG4skNIW9TH7nrrm07rqgf9p5 GcMNM/ahicSXpOYb3x+dDtvj2L9MSi+pLSM08eEbtddpgIsgRtMR2C0lhpOaVmJL GTN8grXaZ2hkJmRmNJOOLNEml7giyzws+n+G3ac1/EYjlUK7RzgaTCKwoIP4T8z3 1oWNLg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc: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=gaZtj5W8VUXhVGMnCQf2AvbtnTkW/jB95uYULjvMR +I=; b=1eM0302JsfRPfNYZigFGlf4pv3B1aGl6WLPXoiSC+RB77eG6ca/Xc7GNl 7LPrYb+2rmzJBK6z6GvFUVAcrlPqnVsRDsZNW7pbLt54e4iOfz76myAyQ0Gmx7h8 HC4dFAw9q4M6O/8/rQpH1JDTawmrsvC0R38ypTt48MZ4ZG6upyHAr9UHVnkWG4WV QwgzDloE0R4o7TN+QDtjbQmBvfb8uWdIUfarGnGdZNRkn0CQXcBfcv6PFi+D8ejQ GXW5U1JLpadxGyZUrzhkkKyB02JMBlX5X9m3X++p5kJvxHysWwjUZVLV7+msH+lv 7Zayd55UV9LdFhmoD1sQZjacDXrgg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedutddrvdehgddugedtucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvufhfffgjkfgfgggtgfesthhqtddttderjeenucfhrhhomheppfhikhho lhgruhhsucftrghthhcuoefpihhkohhlrghushesrhgrthhhrdhorhhgqeenucffohhmrg hinhepuhgsuhhnthhurdgtohhmnecukfhppedukeehrdefrdelgedrudelgeenucfrrghr rghmpehmrghilhhfrhhomheppfhikhholhgruhhssehrrghthhdrohhrghenucevlhhush htvghrufhiiigvpedt X-ME-Proxy: Received: from ebox.rath.org (ebox.rath.org [185.3.94.194]) by mail.messagingengine.com (Postfix) with ESMTPA id 519E1E4309; Fri, 1 Mar 2019 15:40:34 -0500 (EST) Received: from vostro.rath.org (vostro [192.168.12.4]) by ebox.rath.org (Postfix) with ESMTPS id D917483; Fri, 1 Mar 2019 20:40:32 +0000 (UTC) Received: by vostro.rath.org (Postfix, from userid 1000) id 8B274E0089; Fri, 1 Mar 2019 20:40:32 +0000 (GMT) From: Nikolaus Rath To: Miklos Szeredi Cc: 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> <87bm2ymgnt.fsf@vostro.rath.org> Date: Fri, 01 Mar 2019 20:40:32 +0000 In-Reply-To: (Miklos Szeredi's message of "Tue, 26 Feb 2019 21:56:48 +0100") Message-ID: <87woliwcov.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: On Feb 26 2019, Miklos Szeredi wrote: > On Tue, Feb 26, 2019 at 9:35 PM Nikolaus Rath wrote: >> >> [ 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=3D17ffffc000= 00ad, 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)? > > Fuse is careful and basically just falls back on page copy, so it > definitely shouldn't affect data integrity. > > The more interesting question is: how can page_cache_pipe_buf_steal() > return a dirty page? The logic in remove_mapping() should prevent > that, but something is apparently slipping through... > >> >> Is there something I can do to help debugging (and hopefully fixing) >> this? >> >> This is with kernel 4.18 (from Ubuntu cosmic). > > One thought: have you tried reproducing with a recent vanilla > (non-ubuntu) kernel? Yes, I can reproduce with e.g. 5.0.0-050000rc8 (from https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.0-rc8/). However, here the flag value is different: [ 278.183571] fuse: trying to steal weird page [ 278.183576] page=3D000000000aab208c index=3D14944 flags=3D17ffffc00000= 97, count=3D1, mapcount=3D0, mapping=3D (null) (but still the same across all messages observed with this kernel so far). Best, -Nikolaus --=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