From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FA84C43381 for ; Thu, 28 Feb 2019 12:20:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44FC7214D8 for ; Thu, 28 Feb 2019 12:20:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731417AbfB1MUH (ORCPT ); Thu, 28 Feb 2019 07:20:07 -0500 Received: from mx2.suse.de ([195.135.220.15]:51730 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726066AbfB1MUG (ORCPT ); Thu, 28 Feb 2019 07:20:06 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id AB20DAE0F; Thu, 28 Feb 2019 12:20:04 +0000 (UTC) Subject: Re: [PATCH v8 1/4] mm/cma: Add PF flag to force non cma alloc To: "Aneesh Kumar K.V" , akpm@linux-foundation.org, Michal Hocko , Alexey Kardashevskiy , David Gibson , Andrea Arcangeli , mpe@ellerman.id.au Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ingo Molnar , Peter Zijlstra , Matthew Wilcox References: <20190227144736.5872-1-aneesh.kumar@linux.ibm.com> <20190227144736.5872-2-aneesh.kumar@linux.ibm.com> From: Vlastimil Babka Openpgp: preference=signencrypt Autocrypt: addr=vbabka@suse.cz; prefer-encrypt=mutual; keydata= mQINBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 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2ijoaMFTAU+uBtE14UP5F+LWdmRdEGS1Ah1NwooL27uAFllTDQxDhg/+LJ/TqB8ZuidOIy1B xVKRSg3I2m+DUTVqBy7Lixo73hnW69kSjtqCeamY/NSu6LNP+b0wAOKhwz9hBEwEHLp05+mj 5ZFJyfGsOiNUcMoO/17FO4EBxSDP3FDLllpuzlFD7SXkfJaMWYmXIlO0jLzdfwfcnDzBbPwO hBM8hvtsyq8lq8vJOxv6XD6xcTtj5Az8t2JjdUX6SF9hxJpwhBU0wrCoGDkWp4Bbv6jnF7zP Nzftr4l8RuJoywDIiJpdaNpSlXKpj/K6KrnyAI/joYc7 Message-ID: <1d083bf9-0beb-0c49-9aab-c6bc14da46ea@suse.cz> Date: Thu, 28 Feb 2019 13:20:03 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190227144736.5872-2-aneesh.kumar@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/27/19 3:47 PM, Aneesh Kumar K.V wrote: > This patch adds PF_MEMALLOC_NOCMA which make sure any allocation in that context > is marked non-movable and hence cannot be satisfied by CMA region. > > This is useful with get_user_pages_longterm where we want to take a page pin by > migrating pages from CMA region. Marking the section PF_MEMALLOC_NOCMA ensures > that we avoid unnecessary page migration later. > > Suggested-by: Andrea Arcangeli > Reviewed-by: Andrea Arcangeli > Signed-off-by: Aneesh Kumar K.V +CC scheduler guys Do we really take the last available PF flag just so that "we avoid unnecessary page migration later"? If yes, that's a third PF_MEMALLOC flag, should we get separate variable for gfp context at this point? Also I don't like the name PF_MEMALLOC_NOCMA, as it's unnecessarily tied to CMA. If anything it should be e.g. PF_MEMALLOC_NOMOVABLE. Thanks. > --- > include/linux/sched.h | 1 + > include/linux/sched/mm.h | 48 +++++++++++++++++++++++++++++++++------- > 2 files changed, 41 insertions(+), 8 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index f9b43c989577..dfa90088ba08 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1403,6 +1403,7 @@ extern struct pid *cad_pid; > #define PF_UMH 0x02000000 /* I'm an Usermodehelper process */ > #define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_allowed */ > #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ > +#define PF_MEMALLOC_NOCMA 0x10000000 /* All allocation request will have _GFP_MOVABLE cleared */ > #define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */ > #define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezable */ > #define PF_SUSPEND_TASK 0x80000000 /* This thread called freeze_processes() and should not be frozen */ > diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h > index 3bfa6a0cbba4..0cd9f10423fb 100644 > --- a/include/linux/sched/mm.h > +++ b/include/linux/sched/mm.h > @@ -148,17 +148,25 @@ static inline bool in_vfork(struct task_struct *tsk) > * Applies per-task gfp context to the given allocation flags. > * PF_MEMALLOC_NOIO implies GFP_NOIO > * PF_MEMALLOC_NOFS implies GFP_NOFS > + * PF_MEMALLOC_NOCMA implies no allocation from CMA region. > */ > static inline gfp_t current_gfp_context(gfp_t flags) > { > - /* > - * NOIO implies both NOIO and NOFS and it is a weaker context > - * so always make sure it makes precedence > - */ > - if (unlikely(current->flags & PF_MEMALLOC_NOIO)) > - flags &= ~(__GFP_IO | __GFP_FS); > - else if (unlikely(current->flags & PF_MEMALLOC_NOFS)) > - flags &= ~__GFP_FS; > + if (unlikely(current->flags & > + (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_NOCMA))) { > + /* > + * NOIO implies both NOIO and NOFS and it is a weaker context > + * so always make sure it makes precedence > + */ > + if (current->flags & PF_MEMALLOC_NOIO) > + flags &= ~(__GFP_IO | __GFP_FS); > + else if (current->flags & PF_MEMALLOC_NOFS) > + flags &= ~__GFP_FS; > +#ifdef CONFIG_CMA > + if (current->flags & PF_MEMALLOC_NOCMA) > + flags &= ~__GFP_MOVABLE; > +#endif > + } > return flags; > } > > @@ -248,6 +256,30 @@ static inline void memalloc_noreclaim_restore(unsigned int flags) > current->flags = (current->flags & ~PF_MEMALLOC) | flags; > } > > +#ifdef CONFIG_CMA > +static inline unsigned int memalloc_nocma_save(void) > +{ > + unsigned int flags = current->flags & PF_MEMALLOC_NOCMA; > + > + current->flags |= PF_MEMALLOC_NOCMA; > + return flags; > +} > + > +static inline void memalloc_nocma_restore(unsigned int flags) > +{ > + current->flags = (current->flags & ~PF_MEMALLOC_NOCMA) | flags; > +} > +#else > +static inline unsigned int memalloc_nocma_save(void) > +{ > + return 0; > +} > + > +static inline void memalloc_nocma_restore(unsigned int flags) > +{ > +} > +#endif > + > #ifdef CONFIG_MEMCG > /** > * memalloc_use_memcg - Starts the remote memcg charging scope. >