From: Jan Kara Subject: Re: [PATCH 10/13] mm: Wire up MAP_SYNC Date: Tue, 22 Aug 2017 11:36:25 +0200 Message-ID: <20170822093625.GD4909@quack2.suse.cz> References: <20170817160815.30466-1-jack@suse.cz> <20170817160815.30466-11-jack@suse.cz> <20170821213704.GG26220@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org, Andy Lutomirski , linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, Christoph Hellwig , Dan Williams , Boaz Harrosh To: Ross Zwisler Return-path: Received: from mx2.suse.de ([195.135.220.15]:46405 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932205AbdHVJg1 (ORCPT ); Tue, 22 Aug 2017 05:36:27 -0400 Content-Disposition: inline In-Reply-To: <20170821213704.GG26220@linux.intel.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon 21-08-17 15:37:04, Ross Zwisler wrote: > > diff --git a/mm/mmap.c b/mm/mmap.c > > index f19efcf75418..18453c04b09f 100644 > > --- a/mm/mmap.c > > +++ b/mm/mmap.c > > @@ -1423,12 +1423,17 @@ unsigned long do_mmap(struct file *file, unsigned long addr, > > return -ENODEV; > > if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) > > return -EINVAL; > > + if (!(vm_flags & VM_SHARED) && (vm_flags & VM_SYNC)) > > + return -EINVAL; > > I know this will be reworked with Dan's new mmap() interface, but I was > curious what the !(vm_flags & VM_SHARED) check here was for. We're in a > MAP_PRIVATE case, so is it ever possible for VM_SHARED to be set in vm_flags? > I tried to make this happen with some various test scenarios, but wasn't able. I was also caught by this :). Check how MAP_SHARED case above falls through to the MAP_PRIVATE case... Honza -- Jan Kara SUSE Labs, CR