From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752259AbdCHJya (ORCPT ); Wed, 8 Mar 2017 04:54:30 -0500 Received: from mx2.suse.de ([195.135.220.15]:52815 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751235AbdCHJyL (ORCPT ); Wed, 8 Mar 2017 04:54:11 -0500 Date: Wed, 8 Mar 2017 10:35:58 +0100 From: Michal Hocko To: "Darrick J. Wong" Cc: linux-mm@kvack.org, Vlastimil Babka , Johannes Weiner , Mel Gorman , Andrew Morton , LKML Subject: Re: [RFC PATCH 3/4] xfs: map KM_MAYFAIL to __GFP_RETRY_MAYFAIL Message-ID: <20170308093557.GF11028@dhcp22.suse.cz> References: <20170307154843.32516-1-mhocko@kernel.org> <20170307154843.32516-4-mhocko@kernel.org> <20170307170519.GE5281@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170307170519.GE5281@birch.djwong.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 07-03-17 09:05:19, Darrick J. Wong wrote: > On Tue, Mar 07, 2017 at 04:48:42PM +0100, Michal Hocko wrote: > > From: Michal Hocko > > > > KM_MAYFAIL didn't have any suitable GFP_FOO counterpart until recently > > so it relied on the default page allocator behavior for the given set > > of flags. This means that small allocations actually never failed. > > > > Now that we have __GFP_RETRY_MAYFAIL flag which works independently on the > > allocation request size we can map KM_MAYFAIL to it. The allocator will > > try as hard as it can to fulfill the request but fails eventually if > > the progress cannot be made. > > > > Cc: Darrick J. Wong > > Signed-off-by: Michal Hocko > > --- > > fs/xfs/kmem.h | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h > > index ae08cfd9552a..ac80a4855c83 100644 > > --- a/fs/xfs/kmem.h > > +++ b/fs/xfs/kmem.h > > @@ -54,6 +54,16 @@ kmem_flags_convert(xfs_km_flags_t flags) > > lflags &= ~__GFP_FS; > > } > > > > + /* > > + * Default page/slab allocator behavior is to retry for ever > > + * for small allocations. We can override this behavior by using > > + * __GFP_RETRY_MAYFAIL which will tell the allocator to retry as long > > + * as it is feasible but rather fail than retry for ever for all > > s/for ever/forever/ fixed > > > + * request sizes. > > + */ > > + if (flags & KM_MAYFAIL) > > + lflags |= __GFP_RETRY_MAYFAIL; > > But otherwise seems ok from a quick grep -B5 MAYFAIL through the XFS code. > > (Has this been tested anywhere?) not yet, this is more for a discussion at this stage. I plan to run it through xfstests once we agree on the proper semantic. I have to confess I rely on the proper KM_MAYFAIL annotations here, though. Thanks! -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id 67D386B03A1 for ; Wed, 8 Mar 2017 04:36:00 -0500 (EST) Received: by mail-wm0-f69.google.com with SMTP id u9so9309174wme.6 for ; Wed, 08 Mar 2017 01:36:00 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 23si3593119wrz.119.2017.03.08.01.35.58 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 08 Mar 2017 01:35:59 -0800 (PST) Date: Wed, 8 Mar 2017 10:35:58 +0100 From: Michal Hocko Subject: Re: [RFC PATCH 3/4] xfs: map KM_MAYFAIL to __GFP_RETRY_MAYFAIL Message-ID: <20170308093557.GF11028@dhcp22.suse.cz> References: <20170307154843.32516-1-mhocko@kernel.org> <20170307154843.32516-4-mhocko@kernel.org> <20170307170519.GE5281@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170307170519.GE5281@birch.djwong.org> Sender: owner-linux-mm@kvack.org List-ID: To: "Darrick J. Wong" Cc: linux-mm@kvack.org, Vlastimil Babka , Johannes Weiner , Mel Gorman , Andrew Morton , LKML On Tue 07-03-17 09:05:19, Darrick J. Wong wrote: > On Tue, Mar 07, 2017 at 04:48:42PM +0100, Michal Hocko wrote: > > From: Michal Hocko > > > > KM_MAYFAIL didn't have any suitable GFP_FOO counterpart until recently > > so it relied on the default page allocator behavior for the given set > > of flags. This means that small allocations actually never failed. > > > > Now that we have __GFP_RETRY_MAYFAIL flag which works independently on the > > allocation request size we can map KM_MAYFAIL to it. The allocator will > > try as hard as it can to fulfill the request but fails eventually if > > the progress cannot be made. > > > > Cc: Darrick J. Wong > > Signed-off-by: Michal Hocko > > --- > > fs/xfs/kmem.h | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h > > index ae08cfd9552a..ac80a4855c83 100644 > > --- a/fs/xfs/kmem.h > > +++ b/fs/xfs/kmem.h > > @@ -54,6 +54,16 @@ kmem_flags_convert(xfs_km_flags_t flags) > > lflags &= ~__GFP_FS; > > } > > > > + /* > > + * Default page/slab allocator behavior is to retry for ever > > + * for small allocations. We can override this behavior by using > > + * __GFP_RETRY_MAYFAIL which will tell the allocator to retry as long > > + * as it is feasible but rather fail than retry for ever for all > > s/for ever/forever/ fixed > > > + * request sizes. > > + */ > > + if (flags & KM_MAYFAIL) > > + lflags |= __GFP_RETRY_MAYFAIL; > > But otherwise seems ok from a quick grep -B5 MAYFAIL through the XFS code. > > (Has this been tested anywhere?) not yet, this is more for a discussion at this stage. I plan to run it through xfstests once we agree on the proper semantic. I have to confess I rely on the proper KM_MAYFAIL annotations here, though. Thanks! -- Michal Hocko SUSE Labs -- 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