From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754236AbeEaIz5 (ORCPT ); Thu, 31 May 2018 04:55:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:59656 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754040AbeEaIzf (ORCPT ); Thu, 31 May 2018 04:55:35 -0400 Date: Thu, 31 May 2018 10:55:32 +0200 From: Michal Hocko To: Eric Dumazet Cc: David Miller , qing.huang@oracle.com, tariqt@mellanox.com, haakon.bugge@oracle.com, yanjun.zhu@oracle.com, netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, gi-oh.kim@profitbricks.com Subject: Re: [PATCH V4] mlx4_core: allocate ICM memory in page size chunks Message-ID: <20180531085532.GK15278@dhcp22.suse.cz> References: <20180523232246.20445-1-qing.huang@oracle.com> <20180525.102321.858995452200286788.davem@davemloft.net> <7a353b65-6b7f-1aee-1c48-e83c8e02f693@gmail.com> <0e11e0fc-6ccf-aa93-9c4f-b9eae1b90643@gmail.com> <20180531065405.GH15278@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 31-05-18 04:35:31, Eric Dumazet wrote: > > > On 05/31/2018 02:54 AM, Michal Hocko wrote: > > On Tue 29-05-18 23:49:59, Eric Dumazet wrote: > >> > >> > >> On 05/29/2018 11:44 PM, Eric Dumazet wrote: > >> > >>> > >>> And I will add this simple fix, this really should address your initial concern much better. > >>> > >>> @@ -99,6 +100,8 @@ static int mlx4_alloc_icm_pages(struct scatterlist *mem, int order, > >>> { > >>> struct page *page; > >>> > >>> + if (order) > >>> + gfp_mask |= __GFP_NORETRY; > >> > >> and also gfp_mask &= ~__GFP_DIRECT_RECLAIM > > > > JFTR the latter one makes __GFP_NORETRY pointless. Non sleeping allocations > > are not retrying. > > Hi Michal > > Since when this rule is applied ? Well, this has been the case since I remember. ~__GFP_DIRECT_RECLAIM resp. GFP_NOWAIT formerly meant that the allocation doesn't perform _any_ reclaim and therefore it never retries. Why would it? Any retry would just hope for a reclaim on behalf of somebody else. __GFP_NORETRY has always simply stopped retrying after one/few reclaim attempts. Implementation has changed here and there over time but in essence the semantic remained the same. Please have a look at the current documentation in gfp.h file and let me know if you would like some clarfications. > These GFP flags change all the time, I suggest mm experts to cleanup existing call sites ? Do you have any specific areas to look at? > I merely copied/pasted from alloc_skb_with_frags() :/ I will have a look at it. Thanks! -- Michal Hocko SUSE Labs