From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 24 Aug 2017 09:58:38 -0700 From: Christoph Hellwig To: Dan Williams Cc: akpm@linux-foundation.org, Jan Kara , linux-nvdimm@lists.01.org, David Airlie , linux-api@vger.kernel.org, Takashi Iwai , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, Julia Lawall , luto@kernel.org, linux-fsdevel@vger.kernel.org, Daniel Vetter , linux-mm@kvack.org Subject: Re: [PATCH v6 1/5] vfs: add flags parameter to ->mmap() in 'struct file_operations' Message-ID: <20170824165838.GB3121@infradead.org> References: <150353211413.5039.5228914877418362329.stgit@dwillia2-desk3.amr.corp.intel.com> <150353211985.5039.4333061601382775843.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <150353211985.5039.4333061601382775843.stgit@dwillia2-desk3.amr.corp.intel.com> Sender: owner-linux-mm@kvack.org List-ID: On Wed, Aug 23, 2017 at 04:48:40PM -0700, Dan Williams wrote: > We are running running short of vma->vm_flags. We can avoid needing a > new VM_* flag in some cases if the original @flags submitted to mmap(2) > is made available to the ->mmap() 'struct file_operations' > implementation. For example, the proposed addition of MAP_DIRECT can be > implemented without taking up a new vm_flags bit. Another motivation to > avoid vm_flags is that they appear in /proc/$pid/smaps, and we have seen > software that tries to dangerously (TOCTOU) read smaps to infer the > behavior of a virtual address range. > > This conversion was performed by the following semantic patch. There > were a few manual edits for oddities like proc_reg_mmap. > > Thanks to Julia for helping me with coccinelle iteration to cover cases > where the mmap routine is defined in a separate file from the 'struct > file_operations' instance that consumes it. How are we going to check that an instance actually supports any of those flags? -- 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