From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751187AbdAXPSF (ORCPT ); Tue, 24 Jan 2017 10:18:05 -0500 Received: from mx2.suse.de ([195.135.220.15]:55081 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750985AbdAXPSD (ORCPT ); Tue, 24 Jan 2017 10:18:03 -0500 Date: Tue, 24 Jan 2017 16:17:52 +0100 From: Michal Hocko To: Andrew Morton Cc: Vlastimil Babka , David Rientjes , Mel Gorman , Johannes Weiner , Al Viro , linux-mm@kvack.org, LKML , Alexei Starovoitov , Anatoly Stepanov , Andreas Dilger , Andreas Dilger , Anton Vorontsov , Ben Skeggs , Boris Ostrovsky , Colin Cross , Dan Williams , David Sterba , Eric Dumazet , Eric Dumazet , Hariprasad S , Heiko Carstens , Herbert Xu , Ilya Dryomov , Kees Cook , Kent Overstreet , Martin Schwidefsky , "Michael S. Tsirkin" , Mike Snitzer , Oleg Drokin , Paolo Bonzini , "Rafael J. Wysocki" , Santosh Raspatur , Tariq Toukan , "Theodore Ts'o" , Tom Herbert , Tony Luck , "Yan, Zheng" , Yishai Hadas Subject: Re: [PATCH 0/6 v3] kvmalloc Message-ID: <20170124151752.GO6867@dhcp22.suse.cz> References: <20170112153717.28943-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170112153717.28943-1-mhocko@kernel.org> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 12-01-17 16:37:11, Michal Hocko wrote: > Hi, > this has been previously posted as a single patch [1] but later on more > built on top. It turned out that there are users who would like to have > __GFP_REPEAT semantic. This is currently implemented for costly >64B > requests. Doing the same for smaller requests would require to redefine > __GFP_REPEAT semantic in the page allocator which is out of scope of > this series. > > There are many open coded kmalloc with vmalloc fallback instances in > the tree. Most of them are not careful enough or simply do not care > about the underlying semantic of the kmalloc/page allocator which means > that a) some vmalloc fallbacks are basically unreachable because the > kmalloc part will keep retrying until it succeeds b) the page allocator > can invoke a really disruptive steps like the OOM killer to move forward > which doesn't sound appropriate when we consider that the vmalloc > fallback is available. > > As it can be seen implementing kvmalloc requires quite an intimate > knowledge if the page allocator and the memory reclaim internals which > strongly suggests that a helper should be implemented in the memory > subsystem proper. > > Most callers I could find have been converted to use the helper instead. > This is patch 5. There are some more relying on __GFP_REPEAT in the > networking stack which I have converted as well but considering we do > not have a support for __GFP_REPEAT for requests smaller than 64kB I > have marked it RFC. Are there any more comments? I would really appreciate to hear from networking folks before I resubmit the series. Thanks! > [1] http://lkml.kernel.org/r/20170102133700.1734-1-mhocko@kernel.org > -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id 25AED6B027D for ; Tue, 24 Jan 2017 10:18:03 -0500 (EST) Received: by mail-wm0-f72.google.com with SMTP id c206so28674716wme.3 for ; Tue, 24 Jan 2017 07:18:03 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 74si18705222wme.29.2017.01.24.07.18.01 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 24 Jan 2017 07:18:01 -0800 (PST) Date: Tue, 24 Jan 2017 16:17:52 +0100 From: Michal Hocko Subject: Re: [PATCH 0/6 v3] kvmalloc Message-ID: <20170124151752.GO6867@dhcp22.suse.cz> References: <20170112153717.28943-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170112153717.28943-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Vlastimil Babka , David Rientjes , Mel Gorman , Johannes Weiner , Al Viro , linux-mm@kvack.org, LKML , Alexei Starovoitov , Anatoly Stepanov , Andreas Dilger , Andreas Dilger , Anton Vorontsov , Ben Skeggs , Boris Ostrovsky , Colin Cross , Dan Williams , David Sterba , Eric Dumazet , Eric Dumazet , Hariprasad S , Heiko Carstens , Herbert Xu , Ilya Dryomov , Kees Cook , Kent Overstreet , Martin Schwidefsky , "Michael S. Tsirkin" , Mike Snitzer , Oleg Drokin , Paolo Bonzini , "Rafael J. Wysocki" , Santosh Raspatur , Tariq Toukan , Theodore Ts'o , Tom Herbert , Tony Luck , "Yan, Zheng" , Yishai Hadas On Thu 12-01-17 16:37:11, Michal Hocko wrote: > Hi, > this has been previously posted as a single patch [1] but later on more > built on top. It turned out that there are users who would like to have > __GFP_REPEAT semantic. This is currently implemented for costly >64B > requests. Doing the same for smaller requests would require to redefine > __GFP_REPEAT semantic in the page allocator which is out of scope of > this series. > > There are many open coded kmalloc with vmalloc fallback instances in > the tree. Most of them are not careful enough or simply do not care > about the underlying semantic of the kmalloc/page allocator which means > that a) some vmalloc fallbacks are basically unreachable because the > kmalloc part will keep retrying until it succeeds b) the page allocator > can invoke a really disruptive steps like the OOM killer to move forward > which doesn't sound appropriate when we consider that the vmalloc > fallback is available. > > As it can be seen implementing kvmalloc requires quite an intimate > knowledge if the page allocator and the memory reclaim internals which > strongly suggests that a helper should be implemented in the memory > subsystem proper. > > Most callers I could find have been converted to use the helper instead. > This is patch 5. There are some more relying on __GFP_REPEAT in the > networking stack which I have converted as well but considering we do > not have a support for __GFP_REPEAT for requests smaller than 64kB I > have marked it RFC. Are there any more comments? I would really appreciate to hear from networking folks before I resubmit the series. Thanks! > [1] http://lkml.kernel.org/r/20170102133700.1734-1-mhocko@kernel.org > -- 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