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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 A7539C433E1 for ; Mon, 15 Jun 2020 08:24:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84CF42053B for ; Mon, 15 Jun 2020 08:24:58 +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="Uy4iXrsd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728599AbgFOIY4 (ORCPT ); Mon, 15 Jun 2020 04:24:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728422AbgFOIY4 (ORCPT ); Mon, 15 Jun 2020 04:24:56 -0400 Received: from mail-ed1-x543.google.com (mail-ed1-x543.google.com [IPv6:2a00:1450:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58817C05BD43 for ; Mon, 15 Jun 2020 01:24:55 -0700 (PDT) Received: by mail-ed1-x543.google.com with SMTP id o26so10831868edq.0 for ; Mon, 15 Jun 2020 01:24:55 -0700 (PDT) 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=ZhrHsoF+IuuCWsNYTt36CnOUPKOXLNanHzXXw538ijY=; b=Uy4iXrsdKb9Jk+JDiX/Chl9qMKx9QpugSWS5NkriaPMVcmD97vURwhir28xYpfpmqh SPDMoEWcuI4fT1IewSfOaVTFRjIgC0ZgI+aTtHVa8Bt1v7S6TEeRQHOUatH5LzhwpGJ+ 6YojzNXVz6UCsvtK15ZaCT6yZnZ3E7q4SDk9Y= 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=ZhrHsoF+IuuCWsNYTt36CnOUPKOXLNanHzXXw538ijY=; b=BYACubktYF99B1cFWyx7D8uIKVrHLYmKsVU6bjcvpqxh4iphb35lHnZk5zYCVybnBe iGA7oiWYKYkPz+90ZBDwhepRfesEOj/TBDsQsD6w0J/GUyHqLM49I0PKHXfZH+V6EstA NhbytcNkvdEemiTCIDW/YSBOt/eDMG6Nkru/FGSmslFQZADOrRoHggD4QugXbz8anw+z ZJM6XjpK11uwqni1MYqSLSUKKYXiIm0buQVEyydprIEy/KgbmtWrKqJvFbw19sqHRn02 XPAZfSykzHAoYd752KnOVRbXjKXXWoHBUIGIMmmEnA9tBZFcyK52B4TOBd/CAnSCoOao DInQ== X-Gm-Message-State: AOAM530N2IgFbOB9rhamJ3Q/+IPQsj+4xpSDyjcrbo4IcKtFOviQKoO5 0lAJfclqbeVcEOpm9WYmBS/Jg3zo9BY0haPfOMPHfA== X-Google-Smtp-Source: ABdhPJyTYfl7L17Ro5jQwnBv2wTKOxjN4zvQSKG7SGBI4x6Y1v+nhySmXXUUI9zXVpw1KDpsuc+QcQbm++UqGImgmT8= X-Received: by 2002:a50:d785:: with SMTP id w5mr22156433edi.212.1592209493931; Mon, 15 Jun 2020 01:24:53 -0700 (PDT) MIME-Version: 1.0 References: <20200612004644.255692-1-mike.kravetz@oracle.com> <20200612015842.GC23230@ZenIV.linux.org.uk> In-Reply-To: From: Miklos Szeredi Date: Mon, 15 Jun 2020 10:24:42 +0200 Message-ID: Subject: Re: [PATCH v4 1/2] hugetlb: use f_mode & FMODE_HUGETLBFS to identify hugetlbfs files To: Amir Goldstein Cc: Mike Kravetz , Al Viro , Linux MM , linux-fsdevel , overlayfs , linux-kernel , Matthew Wilcox , Colin Walters , Andrew Morton , syzbot , syzkaller-bugs Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 13, 2020 at 8:53 AM Amir Goldstein wrote: > > I also looked at normal filesystem lower and hugetlbfs upper. Yes, overlayfs > > allows this. This is somewhat 'interesting' as write() is not supported in > > hugetlbfs. Writing to files in the overlay actually ended up writing to > > files in the lower filesystem. That seems wrong, but overlayfs is new to me. Yes, this very definitely should not happen. > I am not sure how that happened, but I think that ovl_open_realfile() > needs to fixup f_mode flags FMODE_CAN_WRITE | FMODE_CAN_READ > after open_with_fake_path(). Okay, but how did the write actually get to the lower layer? I failed to reproduce this. Mike, how did you trigger this? Thanks, Miklos