From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id E97A76B0038 for ; Fri, 10 Oct 2014 05:20:59 -0400 (EDT) Received: by mail-pa0-f43.google.com with SMTP id lf10so1407923pab.2 for ; Fri, 10 Oct 2014 02:20:59 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2001:1868:205::9]) by mx.google.com with ESMTPS id fs3si2988343pbb.213.2014.10.10.02.20.57 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 10 Oct 2014 02:20:58 -0700 (PDT) Date: Fri, 10 Oct 2014 11:20:52 +0200 From: Peter Zijlstra Subject: Re: [BUG] mm, thp: khugepaged can't allocate on requested node when confined to a cpuset Message-ID: <20141010092052.GU4750@worktop.programming.kicks-ass.net> References: <20141008191050.GK3778@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141008191050.GK3778@sgi.com> Sender: owner-linux-mm@kvack.org List-ID: To: Alex Thorlton Cc: linux-kernel@vger.kernel.org, Andrew Morton , Mel Gorman , Rik van Riel , Ingo Molnar , "Kirill A. Shutemov" , Hugh Dickins , Bob Liu , Johannes Weiner , linux-mm@kvack.org On Wed, Oct 08, 2014 at 02:10:50PM -0500, Alex Thorlton wrote: > Is this particular bug a known issue? Its not unexpected for me. > I've been trying to come up with > a simple way to fix the bug, but it's a bit difficult since we no longer > have a way to trace back to the task_struct that we're collapsing for > once we've reached get_page_from_freelist. I'm wondering if we might > want to make the cpuset check higher up in the call-chain and then pass > that nodemask down instead of sending a NULL nodemask, as we end up > doing in many (most?) situations. I can think of several problems with > that approach as well, but it's all I've come up with so far. > > The obvious workaround is to not isolate khugepaged to a cpuset, but > since we're allowed to do so, I think the thread should probably behave > appropriately when pinned to a cpuset. > > Any input on this issue is greatly appreciated. Thanks, guys! So for the numa thing we do everything from the affected tasks context. There was a lot of arguments early on that that could never really work, but here we are. Should we convert khugepaged to the same? Drive the whole thing from task_work? That would make this issue naturally go away. -- 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