From: Linus Torvalds Subject: Re: [PATCH] mm: reject MAP_SHARED_VALIDATE without new flags Date: Wed, 27 Jun 2018 19:10:51 -0700 Message-ID: References: <60052659-7b37-cb69-bf9f-1683caa46219@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Christoph Hellwig , Jan Kara , "linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org" , Linux API , zhibli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-xfs , linux-mm , linux-fsdevel , linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Eric Sandeen Return-path: In-Reply-To: <60052659-7b37-cb69-bf9f-1683caa46219-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org On Wed, Jun 27, 2018 at 6:45 PM Eric Sandeen wrote: > > Thus the invalid flag combination of (MAP_SHARED|MAP_PRIVATE) now > passes without error, which is a regression. It's not a regression, it's just new behavior. "regression" doesn't mean "things changed". It means "something broke". What broke? Because if it's some manual page breakage, just fix the manual. That's what "new behavior" is all about. There is nothing that says that "MAP_SHARED_VALIDATE" can't work with just the legacy flags. Because I'd be worried about your patch breaking some actual new user of MAP_SHARED_VALIDATE. Because it's actual *users* of behavior we care about, not some test-suite or manual pages. Linus