From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [13/18] x86_64: Allow fallback for the stack From: Peter Zijlstra In-Reply-To: <200710041356.51750.ak@suse.de> References: <20071004035935.042951211@sgi.com> <20071004040004.708466159@sgi.com> <200710041356.51750.ak@suse.de> Content-Type: text/plain Date: Thu, 04 Oct 2007 14:08:12 +0200 Message-Id: <1191499692.22357.4.camel@twins> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: Christoph Lameter , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, travis@sgi.com List-ID: On Thu, 2007-10-04 at 13:56 +0200, Andi Kleen wrote: > On Thursday 04 October 2007 05:59:48 Christoph Lameter wrote: > > Peter Zijlstra has recently demonstrated that we can have order 1 allocation > > failures under memory pressure with small memory configurations. The > > x86_64 stack has a size of 8k and thus requires a order 1 allocation. > > We've known for ages that it is possible. But it has been always so rare > that it was ignored. > > Is there any evidence this is more common now than it used to be? The order-1 allocation failures where GFP_ATOMIC, because SLUB uses !0 order for everything. Kernel stack allocation is GFP_KERNEL I presume. Also, I use 4k stacks on all my machines. Maybe the cpumask thing needs an extended api, one that falls back to kmalloc if NR_CPUS >> sane. That way that cannot be an argument to inflate stacks. -- 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