From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f179.google.com (mail-qc0-f179.google.com [209.85.216.179]) by kanga.kvack.org (Postfix) with ESMTP id 039626B0070 for ; Wed, 23 Apr 2014 02:15:24 -0400 (EDT) Received: by mail-qc0-f179.google.com with SMTP id m20so493411qcx.24 for ; Tue, 22 Apr 2014 23:15:24 -0700 (PDT) Received: from gate.crashing.org (gate.crashing.org. [63.228.1.57]) by mx.google.com with ESMTPS id a7si2418qcf.27.2014.04.22.23.15.21 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 22 Apr 2014 23:15:22 -0700 (PDT) Message-ID: <1398233655.19682.135.camel@pasglop> Subject: Re: Dirty/Access bits vs. page content From: Benjamin Herrenschmidt Date: Wed, 23 Apr 2014 16:14:15 +1000 In-Reply-To: References: <1398032742.19682.11.camel@pasglop> <1398054064.19682.32.camel@pasglop> <1398057630.19682.38.camel@pasglop> <53558507.9050703@zytor.com> <53559F48.8040808@intel.com> <20140422075459.GD11182@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Hugh Dickins , Jan Kara , Peter Zijlstra , Dave Hansen , "H. Peter Anvin" , "linux-arch@vger.kernel.org" , linux-mm , Russell King - ARM Linux , Tony Luck On Tue, 2014-04-22 at 21:23 -0700, Linus Torvalds wrote: > > But I'm starting to consider this whole thing to be a 3.16 issue by > now. It wasn't as simple as it looked, and while our old location of > set_page_dirty() is clearly wrong, and DaveH even got a test-case for > it (which I initially doubted would even be possible), I still > seriously doubt that anybody sane who cares about data consistency > will do concurrent unmaps (or MADV_DONTNEED) while another writer is > actively using that mapping. I'm more worried about users of unmap_mapping_ranges() than concurrent munmap(). Things like the DRM playing tricks like swapping a mapping from memory to frame buffer and vice-versa. In any case, I agree with delaying that for 3.16, it's still very unlikely that we hit this in any case that actually matters. Cheers, Ben. -- 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