From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 21 Mar 2008 14:57:12 -0700 (PDT) Message-Id: <20080321.145712.198736315.davem@davemloft.net> Subject: Re: [11/14] vcompound: Fallbacks for order 1 stack allocations on IA64 and x86 From: David Miller In-Reply-To: References: <20080321061726.782068299@sgi.com> <20080321.002502.223136918.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org From: Christoph Lameter Date: Fri, 21 Mar 2008 10:40:18 -0700 (PDT) Return-Path: To: clameter@sgi.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: > On Fri, 21 Mar 2008, David Miller wrote: > > > I would be very careful with this especially on IA64. > > > > If the TLB miss or other low-level trap handler depends upon being > > able to dereference thread info, task struct, or kernel stack stuff > > without causing a fault outside of the linear PAGE_OFFSET area, this > > patch will cause problems. > > Hmmm. Does not sound good for arches that cannot handle TLB misses in > hardware. I wonder how arch specific this is? Last time around I was told > that some arches already virtually map their stacks. I'm not saying there is a problem, I'm saying "tread lightly" because there might be one. The thing to do is to first validate the way that IA64 handles recursive TLB misses occuring during an initial TLB miss, and if there are any limitations therein. That's the kind of thing I'm talking about. -- 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