Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936055AbcCQNZK (ORCPT ); Thu, 17 Mar 2016 09:25:10 -0400 Received: from mail.fireflyinternet.com ([87.106.93.118]:59303 "EHLO fireflyinternet.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932614AbcCQNZH (ORCPT ); Thu, 17 Mar 2016 09:25:07 -0400 X-Greylist: delayed 1640 seconds by postgrey-1.27 at vger.kernel.org; Thu, 17 Mar 2016 09:25:06 EDT X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Date: Thu, 17 Mar 2016 12:57:36 +0000 From: Chris Wilson To: Roman Peniaev Cc: intel-gfx@lists.freedesktop.org, Andrew Morton , David Rientjes , Mel Gorman , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/2] mm/vmap: Add a notifier for when we run out of vmap address space Message-ID: <20160317125736.GT14143@nuc-i3427.alporthouse.com> Mail-Followup-To: Chris Wilson , Roman Peniaev , intel-gfx@lists.freedesktop.org, Andrew Morton , David Rientjes , Mel Gorman , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" References: <1458215982-13405-1-git-send-email-chris@chris-wilson.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 674 Lines: 18 On Thu, Mar 17, 2016 at 01:37:06PM +0100, Roman Peniaev wrote: > > + freed = 0; > > + blocking_notifier_call_chain(&vmap_notify_list, 0, &freed); > > It seems to me that alloc_vmap_area() was designed not to sleep, > at least on GFP_NOWAIT path (__GFP_DIRECT_RECLAIM is not set). > > But blocking_notifier_call_chain() might sleep. Indeed, I had not anticipated anybody using GFP_ATOMIC or equivalently restrictive gfp_t for vmap and yes there are such callers. Would guarding the notifier with gfp & __GFP_DIRECT_RECLAIM and !(gfp & __GFP_NORETRY) == be sufficient? Is that enough for GFP_NOFS? -Chris -- Chris Wilson, Intel Open Source Technology Centre