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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 3CBB1C43381 for ; Tue, 26 Feb 2019 13:30:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D75472173C for ; Tue, 26 Feb 2019 13:30:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b="SlUZpLz4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726719AbfBZNaQ (ORCPT ); Tue, 26 Feb 2019 08:30:16 -0500 Received: from mail-io1-f54.google.com ([209.85.166.54]:40542 "EHLO mail-io1-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725977AbfBZNaP (ORCPT ); Tue, 26 Feb 2019 08:30:15 -0500 Received: by mail-io1-f54.google.com with SMTP id p17so10442303iol.7 for ; Tue, 26 Feb 2019 05:30:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=lf3C1vySpmDxXJ/FBmSXkwo7XV+TRsWgqC5dWjt/GSA=; b=SlUZpLz4EdtY7AdRDHA739NoIhyeYJfbUpGC0o6RjRHvvWJO+g5oW1sQCV2aW24Oz7 DrBMgI7j86ts1KALgVpWuamUaHokFZmGxrRFYinJdczuXGE8dCCx8elGtFvqAIq4ymdb uMTPsZ/MHPIKUPbM/7bgGn4gq8crOAxPua3EI= 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=lf3C1vySpmDxXJ/FBmSXkwo7XV+TRsWgqC5dWjt/GSA=; b=F4eKqQsFIMY2OkBtrvJXe6VUxT+gburXRqHC5rlFjCL0GeV0sLJ8XpCr7Zf0Y705Yd yyhEd/jo+kOP54l8uqlJWA2QDPcvFV2m883NMi749mufFGmSdZ/4wS8O+rqJ7XcQlsfk gxLeAUKx971I3WBXwVaK7Mwj4v7mbr3lQnBhfLjEKajucOXB1188NgclqbH+YRcvjaCA pt4SK5ew/4A0kJcqf6CBQIiuGmcODyK7TRT/terJoJ3WO52zT1G0N1fnylNqpf83uYGp Lc1ln0T4O2ZirDV5f2gH9WoXKqqvVOQhpiurAsJdWRcmEh9lHIU+UwwmOYIMB3S/ItpQ EHDg== X-Gm-Message-State: AHQUAuYtGjtGHAs97OgE9dDXoVXW09NjwFWK4/iIXr/pA3K6bNNg9xqJ WjjLDdBIPRoAKdts2TglranVg7vF8eCZAeUhPbDmkg== X-Google-Smtp-Source: AHgI3IajyNOKePv5ly0LFnHR/BEtL1qROq7YUgmjmpZW9x7SZSURFGtuACdLu51sFzurZPHj7TR8sV3mBwFhSzZ8U0A= X-Received: by 2002:a6b:ee02:: with SMTP id i2mr11928402ioh.294.1551187814512; Tue, 26 Feb 2019 05:30:14 -0800 (PST) MIME-Version: 1.0 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> In-Reply-To: From: Miklos Szeredi Date: Tue, 26 Feb 2019 14:30:01 +0100 Message-ID: Subject: Re: [fuse-devel] fuse: trying to steal weird page To: fuse-devel Cc: linux-fsdevel Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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 exactly > > >> the same as last time (value of flags, etc)? > > > > > > The flags, count, mapcount and mapping values are always the same. The > > > page and index is varying. So the general format is: > > > > > > [ 2562.773181] fuse: trying to steal weird page > > > [ 2562.773187] page= index= > > > flags=17ffffc00000ad, count=1, mapcount=0, mapping= (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