From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH v7 07/22] Replace the XIP page fault handler with the DAX page fault handler Date: Mon, 11 Aug 2014 10:13:08 -0400 Message-ID: <20140811141308.GZ6754@linux.intel.com> References: <20140409102758.GM32103@quack.suse.cz> <20140409205111.GG5727@linux.intel.com> <20140409214331.GQ32103@quack.suse.cz> <20140729121259.GL6754@linux.intel.com> <20140729210457.GA17807@quack.suse.cz> <20140729212333.GO6754@linux.intel.com> <20140730095229.GA19205@quack.suse.cz> <20140809110000.GA32313@linux.intel.com> <20140811085147.GB29526@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20140811085147.GB29526@quack.suse.cz> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Aug 11, 2014 at 10:51:47AM +0200, Jan Kara wrote: > So I'm afraid we'll have to find some other way to synchronize > page faults and truncate / punch hole in DAX. What if we don't? If we hit the race (which is vanishingly unlikely with real applications), the consequence is simply that after a truncate, a file may be left with one or two blocks allocated somewhere after i_size. As I understand it, that's not a real problem; they're temporarily unavailable for allocation but will be freed on file removal or the next truncation of that file. I'm also still considering the possibility of having truncate-down block until all mmaps that extend after the new i_size have been removed ... -- 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