Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754605AbdFWI5B (ORCPT ); Fri, 23 Jun 2017 04:57:01 -0400 Received: from mail-wr0-f195.google.com ([209.85.128.195]:35083 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754023AbdFWIyA (ORCPT ); Fri, 23 Jun 2017 04:54:00 -0400 From: Michal Hocko To: Andrew Morton Cc: Vlastimil Babka , Johannes Weiner , Mel Gorman , NeilBrown , LKML , , Michal Hocko , Christoph Hellwig , "Darrick J. Wong" Subject: [PATCH 3/6] xfs: map KM_MAYFAIL to __GFP_RETRY_MAYFAIL Date: Fri, 23 Jun 2017 10:53:42 +0200 Message-Id: <20170623085345.11304-4-mhocko@kernel.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170623085345.11304-1-mhocko@kernel.org> References: <20170623085345.11304-1-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1488 Lines: 43 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. It does so without triggering the OOM killer which can be seen as an improvement because KM_MAYFAIL users should be able to deal with allocation failures. Cc: Darrick J. Wong Cc: Christoph Hellwig 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 d6ea520162b2..4d85992d75b2 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 forever for all + * request sizes. + */ + if (flags & KM_MAYFAIL) + lflags |= __GFP_RETRY_MAYFAIL; + if (flags & KM_ZERO) lflags |= __GFP_ZERO; -- 2.11.0