Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933333AbdCGV1l (ORCPT ); Tue, 7 Mar 2017 16:27:41 -0500 Received: from aserp1050.oracle.com ([141.146.126.70]:46577 "EHLO aserp1050.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753196AbdCGVYI (ORCPT ); Tue, 7 Mar 2017 16:24:08 -0500 Date: Tue, 7 Mar 2017 09:05:19 -0800 From: "Darrick J. Wong" To: Michal Hocko Cc: linux-mm@kvack.org, Vlastimil Babka , Johannes Weiner , Mel Gorman , Andrew Morton , LKML , Michal Hocko Subject: Re: [RFC PATCH 3/4] xfs: map KM_MAYFAIL to __GFP_RETRY_MAYFAIL Message-ID: <20170307170519.GE5281@birch.djwong.org> References: <20170307154843.32516-1-mhocko@kernel.org> <20170307154843.32516-4-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170307154843.32516-4-mhocko@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Source-IP: aserp1040.oracle.com [141.146.126.69] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1575 Lines: 52 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/ > + * 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?) --D > + > if (flags & KM_ZERO) > lflags |= __GFP_ZERO; > > -- > 2.11.0 >