From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR Date: Thu, 5 Jan 2017 11:39:16 -0800 Message-ID: <161ece66-fbf4-cb89-3da6-91b4851af69f@intel.com> References: <20161227015413.187403-1-kirill.shutemov@linux.intel.com> <20161227015413.187403-30-kirill.shutemov@linux.intel.com> <5a3dcc25-b264-37c7-c090-09981b23940d@intel.com> <20170105192910.q26ozg4ci4i3j2ai@black.fi.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170105192910.q26ozg4ci4i3j2ai@black.fi.intel.com> Sender: owner-linux-mm@kvack.org To: "Kirill A. Shutemov" Cc: Linus Torvalds , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , Arnd Bergmann , "H. Peter Anvin" , Andi Kleen , Andy Lutomirski , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org List-Id: linux-api@vger.kernel.org On 01/05/2017 11:29 AM, Kirill A. Shutemov wrote: > On Thu, Jan 05, 2017 at 11:13:57AM -0800, Dave Hansen wrote: >> On 12/26/2016 05:54 PM, Kirill A. Shutemov wrote: >>> MM would use min(RLIMIT_VADDR, TASK_SIZE) as upper limit of virtual >>> address available to map by userspace. >> >> What happens to existing mappings above the limit when this upper limit >> is dropped? > > Nothing: we only prevent creating new mappings. All existing are not > affected. > > The semantics here the same as with other resource limits. > >> Similarly, why do we do with an application running with something >> incompatible with the larger address space that tries to raise the >> limit? Say, legacy MPX. > > It has to know what it does. Yes, it can change limit to the point where > application is unusable. But you can to the same with other limits. I'm not sure I'm comfortable with this. Do other rlimit changes cause silent data corruption? I'm pretty sure doing this to MPX would. -- 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