From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f199.google.com (mail-wj0-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 3614D6B0069 for ; Thu, 8 Dec 2016 08:51:49 -0500 (EST) Received: by mail-wj0-f199.google.com with SMTP id hb5so96253699wjc.2 for ; Thu, 08 Dec 2016 05:51:49 -0800 (PST) Received: from mail-wj0-f196.google.com (mail-wj0-f196.google.com. [209.85.210.196]) by mx.google.com with ESMTPS id 203si13319364wmh.55.2016.12.08.05.51.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 08 Dec 2016 05:51:48 -0800 (PST) Received: by mail-wj0-f196.google.com with SMTP id he10so40402398wjc.2 for ; Thu, 08 Dec 2016 05:51:47 -0800 (PST) Date: Thu, 8 Dec 2016 14:51:46 +0100 From: Michal Hocko Subject: Re: [RFC PATCH] mm: introduce kv[mz]alloc helpers Message-ID: <20161208135145.GD26530@dhcp22.suse.cz> References: <20161208103300.23217-1-mhocko@kernel.org> <86cabb7a-1756-4d12-7ba4-776f66f6bb86@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86cabb7a-1756-4d12-7ba4-776f66f6bb86@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: David Hildenbrand Cc: linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , David Rientjes , Mel Gorman , Johannes Weiner , Anatoly Stepanov , LKML , Paolo Bonzini , Mike Snitzer , dm-devel@redhat.com, "Michael S. Tsirkin" , Theodore Ts'o , kvm@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org On Thu 08-12-16 14:00:20, David Hildenbrand wrote: > Am 08.12.2016 um 11:33 schrieb Michal Hocko: > > From: Michal Hocko > > > > Using kmalloc with the vmalloc fallback for larger allocations is a > > common pattern in the kernel code. Yet we do not have any common helper > > for that and so users have invented their own helpers. Some of them are > > really creative when doing so. Let's just add kv[mz]alloc and make sure > > it is implemented properly. This implementation makes sure to not make > > a large memory pressure for > PAGE_SZE requests (__GFP_NORETRY) and also > > to not warn about allocation failures. This also rules out the OOM > > killer as the vmalloc is a more approapriate fallback than a disruptive > > user visible action. > > > > This patch also changes some existing users and removes helpers which > > are specific for them. In some cases this is not possible (e.g. > > ext4_kvmalloc, libcfs_kvzalloc, __aa_kvmalloc) because those seems to be > > broken and require GFP_NO{FS,IO} context which is not vmalloc compatible > > in general (note that the page table allocation is GFP_KERNEL). Those > > need to be fixed separately. > > > > apparmor has already claimed kv[mz]alloc so remove those and use > > __aa_kvmalloc instead to prevent from the naming clashes. > > > > Cc: Paolo Bonzini > > Cc: Mike Snitzer > > Cc: dm-devel@redhat.com > > Cc: "Michael S. Tsirkin" > > Cc: "Theodore Ts'o" > > Cc: kvm@vger.kernel.org > > Cc: linux-ext4@vger.kernel.org > > Cc: linux-f2fs-devel@lists.sourceforge.net > > Cc: linux-security-module@vger.kernel.org > > Signed-off-by: Michal Hocko > > I remember yet another similar user in arch/s390/kvm/kvm-s390.c > -> kvm_s390_set_skeys() > > ... > keys = kmalloc_array(args->count, sizeof(uint8_t), > GFP_KERNEL | __GFP_NOWARN); > if (!keys) > vmalloc(sizeof(uint8_t) * args->count); > ... > > would kvmalloc_array make sense? (it would even make the code here > less error prone and better to read) Well, if there are more users like that then why not. I just do not want to duplicate the whole kmalloc API right now. The above could be trivially changed to kvmalloc(args->count * sizeof(uint8_t), GFP_KERNEL) so a special API might not be really needed. -- 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