From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f177.google.com (mail-lb0-f177.google.com [209.85.217.177]) by kanga.kvack.org (Postfix) with ESMTP id 281A06B0093 for ; Wed, 17 Jun 2015 07:45:32 -0400 (EDT) Received: by lbbwc1 with SMTP id wc1so29825107lbb.2 for ; Wed, 17 Jun 2015 04:45:31 -0700 (PDT) Received: from mx02.imt-systems.com (mx02.imt-systems.com. [212.224.83.171]) by mx.google.com with ESMTPS id fk12si7329329wjc.153.2015.06.17.04.45.29 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Jun 2015 04:45:30 -0700 (PDT) Received: from ucsinet10.imt-systems.com (ucsinet10.imt-systems.com [212.224.83.165]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx02.imt-systems.com (Postfix) with ESMTPS id 3mBPj42Z4hzMwm4L for ; Wed, 17 Jun 2015 13:45:28 +0200 (CEST) Received: from mail-wi0-f171.google.com (mail-wi0-f171.google.com [209.85.212.171]) (authenticated bits=0) by ucsinet10.imt-systems.com (8.14.7/8.14.7) with ESMTP id t5HBjSdZ020371 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 17 Jun 2015 13:45:28 +0200 Received: by wifx6 with SMTP id x6so50180682wif.0 for ; Wed, 17 Jun 2015 04:45:27 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <557E6C0C.3050802@monom.org> References: <557E6C0C.3050802@monom.org> Date: Wed, 17 Jun 2015 13:45:27 +0200 Message-ID: Subject: Re: mm: shmem_zero_setup skip security check and lockdep conflict with XFS From: Morten Stevens Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Daniel Wagner Cc: Hugh Dickins , Linus Torvalds , Prarit Bhargava , Morten Stevens , Dave Chinner , Eric Paris , Eric Sandeen , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org 2015-06-15 8:09 GMT+02:00 Daniel Wagner : > On 06/14/2015 06:48 PM, Hugh Dickins wrote: >> It appears that, at some point last year, XFS made directory handling >> changes which bring it into lockdep conflict with shmem_zero_setup(): >> it is surprising that mmap() can clone an inode while holding mmap_sem, >> but that has been so for many years. >> >> Since those few lockdep traces that I've seen all implicated selinux, >> I'm hoping that we can use the __shmem_file_setup(,,,S_PRIVATE) which >> v3.13's commit c7277090927a ("security: shmem: implement kernel private >> shmem inodes") introduced to avoid LSM checks on kernel-internal inodes: >> the mmap("/dev/zero") cloned inode is indeed a kernel-internal detail. >> >> This also covers the !CONFIG_SHMEM use of ramfs to support /dev/zero >> (and MAP_SHARED|MAP_ANONYMOUS). I thought there were also drivers >> which cloned inode in mmap(), but if so, I cannot locate them now. >> >> Reported-and-tested-by: Prarit Bhargava >> Reported-by: Daniel Wagner > > Reported-and-tested-by: Daniel Wagner > > Sorry for the long delay. It took me a while to figure out my original > setup. I could verify that this patch made the lockdep message go away > on 4.0-rc6 and also on 4.1-rc8. Yes, it's also fixed for me after applying this patch to 4.1-rc8. Best regards, Morten -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org