From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753168AbbDBJh0 (ORCPT ); Thu, 2 Apr 2015 05:37:26 -0400 Received: from verein.lst.de ([213.95.11.211]:35004 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751617AbbDBJhX (ORCPT ); Thu, 2 Apr 2015 05:37:23 -0400 Date: Thu, 2 Apr 2015 11:37:21 +0200 From: Christoph Hellwig To: "Elliott, Robert (Server Storage)" Cc: Christoph Hellwig , "linux-nvdimm@ml01.01.org" , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , "ross.zwisler@linux.intel.com" , "axboe@kernel.dk" , "boaz@plexistor.com" , "Kani, Toshimitsu" Subject: Re: another pmem variant V2 Message-ID: <20150402093721.GD14209@lst.de> References: <1427358764-6126-1-git-send-email-hch@lst.de> <94D0CD8314A33A4D9D801C0FE68B40295A8556BB@G9W0745.americas.hpqcorp.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <94D0CD8314A33A4D9D801C0FE68B40295A8556BB@G9W0745.americas.hpqcorp.net> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 01, 2015 at 07:33:38PM +0000, Elliott, Robert (Server Storage) wrote: > I triggered a paging error in the memcpy call for a block read > from system-udevd (actually in a modified memcpy() for the cache > attribute experiments). > > 1. This triggered an illegal schedule() call from an atomic context. > The call trace is shown below. > > 2. memcpy() doesn't provide exception handling or error reporting. > Some functions like do so, like __copy_user_nocache in > arch/x85/lib/copy_user_nocache_64.S. > > Should pmem only use functions that do so, if available on the > architecture? We'll need to define an interface for the function to use if it isn't plain memcpy, which would include that detail. But I can't see how that memcpy should ever have to handle a page fault, I'd be curious how your reproduces this issue.