From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Date: Fri, 22 Mar 2019 22:12:55 +0000 Subject: Re: [RESEND 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast Message-Id: List-Id: References: <20190317183438.2057-1-ira.weiny@intel.com> <20190317183438.2057-5-ira.weiny@intel.com> In-Reply-To: <20190317183438.2057-5-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ira.weiny@intel.com Cc: Andrew Morton , John Hubbard , Michal Hocko , "Kirill A. Shutemov" , Peter Zijlstra , Jason Gunthorpe , Benjamin Herrenschmidt , Paul Mackerras , "David S. Miller" , Martin Schwidefsky , Heiko Carstens , Rich Felker , Yoshinori Sato , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Ralf Baechle , James Hogan , linux-mm , Linux Kernel Mailing List , linux-mips@vger.kernel.org, linuxppc-dev , linux-s390 , Linux-sh , sparclinux@vger.kernel.org, linux-rdma@vger.kernel.org, "netdev@vger.kernel.org" On Sun, Mar 17, 2019 at 7:36 PM wrote: > > From: Ira Weiny > > DAX pages were previously unprotected from longterm pins when users > called get_user_pages_fast(). > > Use the new FOLL_LONGTERM flag to check for DEVMAP pages and fall > back to regular GUP processing if a DEVMAP page is encountered. > > Signed-off-by: Ira Weiny > --- > mm/gup.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 0684a9536207..173db0c44678 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1600,6 +1600,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, > goto pte_unmap; > > if (pte_devmap(pte)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + goto pte_unmap; > + > pgmap = get_dev_pagemap(pte_pfn(pte), pgmap); > if (unlikely(!pgmap)) { > undo_dev_pagemap(nr, nr_start, pages); > @@ -1739,8 +1742,11 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, > if (!pmd_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pmd_devmap(orig)) > + if (pmd_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr); > + } > > refs = 0; > page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > @@ -1777,8 +1783,11 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, > if (!pud_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pud_devmap(orig)) > + if (pud_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr); > + } > > refs = 0; > page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); > @@ -2066,8 +2075,20 @@ int get_user_pages_fast(unsigned long start, int nr_pages, > start += nr << PAGE_SHIFT; > pages += nr; > > - ret = get_user_pages_unlocked(start, nr_pages - nr, pages, > - gup_flags); > + if (gup_flags & FOLL_LONGTERM) { > + down_read(¤t->mm->mmap_sem); > + ret = __gup_longterm_locked(current, current->mm, > + start, nr_pages - nr, > + pages, NULL, gup_flags); > + up_read(¤t->mm->mmap_sem); > + } else { > + /* > + * retain FAULT_FOLL_ALLOW_RETRY optimization if > + * possible > + */ > + ret = get_user_pages_unlocked(start, nr_pages - nr, > + pages, gup_flags); I couldn't immediately grok why this path needs to branch on FOLL_LONGTERM? Won't get_user_pages_unlocked(..., FOLL_LONGTERM) do the right thing? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: Re: [RESEND 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast Date: Fri, 22 Mar 2019 15:12:55 -0700 Message-ID: References: <20190317183438.2057-1-ira.weiny@intel.com> <20190317183438.2057-5-ira.weiny@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20190317183438.2057-5-ira.weiny@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: ira.weiny@intel.com Cc: Andrew Morton , John Hubbard , Michal Hocko , "Kirill A. Shutemov" , Peter Zijlstra , Jason Gunthorpe , Benjamin Herrenschmidt , Paul Mackerras , "David S. Miller" , Martin Schwidefsky , Heiko Carstens , Rich Felker , Yoshinori Sato , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Ralf Baechle , James Hogan , linux-mm Linux Kernel Mailing List List-Id: linux-rdma@vger.kernel.org On Sun, Mar 17, 2019 at 7:36 PM wrote: > > From: Ira Weiny > > DAX pages were previously unprotected from longterm pins when users > called get_user_pages_fast(). > > Use the new FOLL_LONGTERM flag to check for DEVMAP pages and fall > back to regular GUP processing if a DEVMAP page is encountered. > > Signed-off-by: Ira Weiny > --- > mm/gup.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 0684a9536207..173db0c44678 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1600,6 +1600,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, > goto pte_unmap; > > if (pte_devmap(pte)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + goto pte_unmap; > + > pgmap = get_dev_pagemap(pte_pfn(pte), pgmap); > if (unlikely(!pgmap)) { > undo_dev_pagemap(nr, nr_start, pages); > @@ -1739,8 +1742,11 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, > if (!pmd_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pmd_devmap(orig)) > + if (pmd_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr); > + } > > refs = 0; > page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > @@ -1777,8 +1783,11 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, > if (!pud_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pud_devmap(orig)) > + if (pud_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr); > + } > > refs = 0; > page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); > @@ -2066,8 +2075,20 @@ int get_user_pages_fast(unsigned long start, int nr_pages, > start += nr << PAGE_SHIFT; > pages += nr; > > - ret = get_user_pages_unlocked(start, nr_pages - nr, pages, > - gup_flags); > + if (gup_flags & FOLL_LONGTERM) { > + down_read(¤t->mm->mmap_sem); > + ret = __gup_longterm_locked(current, current->mm, > + start, nr_pages - nr, > + pages, NULL, gup_flags); > + up_read(¤t->mm->mmap_sem); > + } else { > + /* > + * retain FAULT_FOLL_ALLOW_RETRY optimization if > + * possible > + */ > + ret = get_user_pages_unlocked(start, nr_pages - nr, > + pages, gup_flags); I couldn't immediately grok why this path needs to branch on FOLL_LONGTERM? Won't get_user_pages_unlocked(..., FOLL_LONGTERM) do the right thing? 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=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 2535EC10F0E for ; Fri, 22 Mar 2019 22:13:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC72521900 for ; Fri, 22 Mar 2019 22:13:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="Zb9Bl7Bn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728189AbfCVWNI (ORCPT ); Fri, 22 Mar 2019 18:13:08 -0400 Received: from mail-it1-f196.google.com ([209.85.166.196]:37288 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727606AbfCVWNI (ORCPT ); Fri, 22 Mar 2019 18:13:08 -0400 Received: by mail-it1-f196.google.com with SMTP id z124so5766936itc.2; Fri, 22 Mar 2019 15:13:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VnWfr5Cz9g8Ts5McgdJK3bb2nMan4nq5nXqWONnMsfs=; b=Zb9Bl7Bn4sqZs4rM2mwfzJd7rKnn+/+6ONyGGwJqa1scMrXWXjmi9yoQBAbfMlLpgS RGV1LtFJyFJAtRyqt7x4phr5CYLMLHxyjOqtaGBIgKlABbih3LbLp5n0OYCbWIHRLaHd TTQ98w8krLJnK39QE8Dp0ik11E8+01Sgyn1wW72V9bUGSzJ08oA4QbCqRZA5AnJQLOtm o3basMsLTQYqNorbmDjd4KoyjPrND/z4P2rEoZfVYQnDMfAEdcsp9b63663QinvyZoJp HOu5mHwb07RCBU+1v7ChvrPznU5/HmjF8OEnSTsQgs+cld8MrdbVwNZKadLpnlT93nHs Yb2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VnWfr5Cz9g8Ts5McgdJK3bb2nMan4nq5nXqWONnMsfs=; b=ccLQBoMktj+EGlvYTMnJ5ebXJJXkpSI17oyqZDEwmFSSCVRurSA6lDn53Bf1q2N4Zi /mfNhg/da013n5C8g37oCBgu+s7ZwvOd00iQlWY/6pU+5Ka8Cf46p3+YIsggiA5Qb31F DYB9PqNJB2svbkkxKrXdq4cQfsLCiLUS90WgKbOTSKqmt4RpjT6TmlSe8ohOTuyCaD9Z uJeAAmFhMRRmB5OpWMDkLrNxp5putajre62dwMJK/JXrQx7BEJPAJs04rHVvkcVpALC+ ryL8THaArahcarhgknapFHuhBV+vdP2J3Jn742KsMBOS+cYRf2yoOZKLPEtZUF203Jlw TrYA== X-Gm-Message-State: APjAAAUuLGoy3fMVubGbbqGOtpN5QdZhK61fveUtg2A9wDgBPNPXrO4+ clm9fbFR3BmLnP7CS2wcTKKh2IXLSdHU39RJ7aM= X-Google-Smtp-Source: APXvYqwPCPjaWzKVXpURWg65K5fkBoLbrluPEoFqqgn2rT6o/InM1ko8UbBUfBaLU8H/oERd+79+VhkVDmrMWUaE2i4= X-Received: by 2002:a02:c007:: with SMTP id y7mr8517902jai.1.1553292786464; Fri, 22 Mar 2019 15:13:06 -0700 (PDT) MIME-Version: 1.0 References: <20190317183438.2057-1-ira.weiny@intel.com> <20190317183438.2057-5-ira.weiny@intel.com> In-Reply-To: <20190317183438.2057-5-ira.weiny@intel.com> From: Dan Williams Date: Fri, 22 Mar 2019 15:12:55 -0700 Message-ID: Subject: Re: [RESEND 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast To: ira.weiny@intel.com Cc: Andrew Morton , John Hubbard , Michal Hocko , "Kirill A. Shutemov" , Peter Zijlstra , Jason Gunthorpe , Benjamin Herrenschmidt , Paul Mackerras , "David S. Miller" , Martin Schwidefsky , Heiko Carstens , Rich Felker , Yoshinori Sato , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Ralf Baechle , James Hogan , linux-mm , Linux Kernel Mailing List , linux-mips@vger.kernel.org, linuxppc-dev , linux-s390 , Linux-sh , sparclinux@vger.kernel.org, linux-rdma@vger.kernel.org, "netdev@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 17, 2019 at 7:36 PM wrote: > > From: Ira Weiny > > DAX pages were previously unprotected from longterm pins when users > called get_user_pages_fast(). > > Use the new FOLL_LONGTERM flag to check for DEVMAP pages and fall > back to regular GUP processing if a DEVMAP page is encountered. > > Signed-off-by: Ira Weiny > --- > mm/gup.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 0684a9536207..173db0c44678 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1600,6 +1600,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, > goto pte_unmap; > > if (pte_devmap(pte)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + goto pte_unmap; > + > pgmap = get_dev_pagemap(pte_pfn(pte), pgmap); > if (unlikely(!pgmap)) { > undo_dev_pagemap(nr, nr_start, pages); > @@ -1739,8 +1742,11 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, > if (!pmd_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pmd_devmap(orig)) > + if (pmd_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr); > + } > > refs = 0; > page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > @@ -1777,8 +1783,11 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, > if (!pud_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pud_devmap(orig)) > + if (pud_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr); > + } > > refs = 0; > page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); > @@ -2066,8 +2075,20 @@ int get_user_pages_fast(unsigned long start, int nr_pages, > start += nr << PAGE_SHIFT; > pages += nr; > > - ret = get_user_pages_unlocked(start, nr_pages - nr, pages, > - gup_flags); > + if (gup_flags & FOLL_LONGTERM) { > + down_read(¤t->mm->mmap_sem); > + ret = __gup_longterm_locked(current, current->mm, > + start, nr_pages - nr, > + pages, NULL, gup_flags); > + up_read(¤t->mm->mmap_sem); > + } else { > + /* > + * retain FAULT_FOLL_ALLOW_RETRY optimization if > + * possible > + */ > + ret = get_user_pages_unlocked(start, nr_pages - nr, > + pages, gup_flags); I couldn't immediately grok why this path needs to branch on FOLL_LONGTERM? Won't get_user_pages_unlocked(..., FOLL_LONGTERM) do the right thing? 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=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 0040FC43381 for ; Fri, 22 Mar 2019 22:13:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 93C9F21900 for ; Fri, 22 Mar 2019 22:13:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="Zb9Bl7Bn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 93C9F21900 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EEBAA6B0005; Fri, 22 Mar 2019 18:13:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E703F6B0006; Fri, 22 Mar 2019 18:13:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D12466B0007; Fri, 22 Mar 2019 18:13:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-io1-f72.google.com (mail-io1-f72.google.com [209.85.166.72]) by kanga.kvack.org (Postfix) with ESMTP id AC5556B0005 for ; Fri, 22 Mar 2019 18:13:07 -0400 (EDT) Received: by mail-io1-f72.google.com with SMTP id n15so2930625ioc.0 for ; Fri, 22 Mar 2019 15:13:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=VnWfr5Cz9g8Ts5McgdJK3bb2nMan4nq5nXqWONnMsfs=; b=nR0SPk2KJHw++ud1lJKIBfxlB0c31aVsd2CnKGrHqfE78LryBHDTa+YG/tt5Reir5s ZKSCmvExF3Tvza2VCuUjbJ3UCYQg6P2mbi/9Ds0+q8eSibMZFY6CfeF6vWrj+8Gfcbpa 6BVatf8GkHcIUptVuogvPoK/TOJMprRnsoNdB3EgCclH9bHg02PyDi7lAP+ta7fR/vJe +2JcJNpV+01J/CZjmKwfsLdKNcP66bCOxf4oD1qxND0IRiJ7X20Q2cybk4RjbEkOk+AV z1IygKJ+nJY8/sgjgnG48hpMLYNvYlu8UGnVkFgQdJe1uMCie2JPcwljmVISXPonwn/7 yxWQ== X-Gm-Message-State: APjAAAWWN3x/GQ6yb5ineIKNdEHwy8D7fXqAai4RmokDG1JPb7bTsxSB 20ENwjtYKB6dmQbNRMQzeMiY1lAg6Jwg4Vf7JNRujgPHx9Eee3RqCusc7d+JEiWHuTqwegg49JF zRzYTJTW+q4n6HBbBL0U4YbzN6Mr88ih/hOIf0IbxaM7+9XpqJRcczIzo6zYGMGg= X-Received: by 2002:a02:b008:: with SMTP id p8mr7750063jah.90.1553292787479; Fri, 22 Mar 2019 15:13:07 -0700 (PDT) X-Received: by 2002:a02:b008:: with SMTP id p8mr7750023jah.90.1553292786843; Fri, 22 Mar 2019 15:13:06 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1553292786; cv=none; d=google.com; s=arc-20160816; b=l5rAaE4V0yhJJ8/wOPndE+hoOwgIQoRvmC0TOlzVmpFP72tdiQhxnpWIrNFIKzAQlW dVaBz9qwSExihD7zpF45NlgVsNtS1VNQl0g7zz9kJs2K23MdsJanK3Ty1w7zkvKGMJrp NMr3/pZwEl2GD6Fm6oEtFPbUE+yApRgfPHdcdIQ1Z1VHdLtiNuNZ8KVgMbi6RN9/VP8P PBvpoBrw0tgIuXzryO6La3NGfnyTwHkrBMhzJ3DGMyI0EctyE2fcREoyZIZeZvO5tAYb KU5ka5h23lAQWQ+E+naPh32mDOL28AJI84a5kLbn9od0Ia2tR9E30TGGYwcm3zUTFWPV +2EQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=VnWfr5Cz9g8Ts5McgdJK3bb2nMan4nq5nXqWONnMsfs=; b=VDgkBRUHdz6MdkhAcwrSKCV6CyGzGN2MgHP8k3TBEvpSFOZU6Q44iC6gb1rDX82R3B 0gvhQnBqZxlL9l0tpuLvppVX7b+RzimpQxsQ6WSWJJ2CnyS+X7G7daCY04YJNrwW72Bh 39DD2vcdoiPwvgc+tzRq21eMaesxdou2myPmdsNiZCchJoo/1jeLJkpPpftrZ7ZkhTwJ MoGuIw0vfOS8WyCDsN6/E509OLckUINsuiI9yBDioVowP+ehfAt2e4ZzSaOttqQx66Nk h0UyIpgjlKGL3Hx+1WuKxruQ/ZQLKKEZ1zl52G0cKDEBLd9nv5gbKxiPevncq6460mgw IY7w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=Zb9Bl7Bn; spf=pass (google.com: domain of dan.j.williams@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id n129sor24246469jaa.12.2019.03.22.15.13.06 for (Google Transport Security); Fri, 22 Mar 2019 15:13:06 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=Zb9Bl7Bn; spf=pass (google.com: domain of dan.j.williams@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VnWfr5Cz9g8Ts5McgdJK3bb2nMan4nq5nXqWONnMsfs=; b=Zb9Bl7Bn4sqZs4rM2mwfzJd7rKnn+/+6ONyGGwJqa1scMrXWXjmi9yoQBAbfMlLpgS RGV1LtFJyFJAtRyqt7x4phr5CYLMLHxyjOqtaGBIgKlABbih3LbLp5n0OYCbWIHRLaHd TTQ98w8krLJnK39QE8Dp0ik11E8+01Sgyn1wW72V9bUGSzJ08oA4QbCqRZA5AnJQLOtm o3basMsLTQYqNorbmDjd4KoyjPrND/z4P2rEoZfVYQnDMfAEdcsp9b63663QinvyZoJp HOu5mHwb07RCBU+1v7ChvrPznU5/HmjF8OEnSTsQgs+cld8MrdbVwNZKadLpnlT93nHs Yb2w== X-Google-Smtp-Source: APXvYqwPCPjaWzKVXpURWg65K5fkBoLbrluPEoFqqgn2rT6o/InM1ko8UbBUfBaLU8H/oERd+79+VhkVDmrMWUaE2i4= X-Received: by 2002:a02:c007:: with SMTP id y7mr8517902jai.1.1553292786464; Fri, 22 Mar 2019 15:13:06 -0700 (PDT) MIME-Version: 1.0 References: <20190317183438.2057-1-ira.weiny@intel.com> <20190317183438.2057-5-ira.weiny@intel.com> In-Reply-To: <20190317183438.2057-5-ira.weiny@intel.com> From: Dan Williams Date: Fri, 22 Mar 2019 15:12:55 -0700 Message-ID: Subject: Re: [RESEND 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast To: ira.weiny@intel.com Cc: Andrew Morton , John Hubbard , Michal Hocko , "Kirill A. Shutemov" , Peter Zijlstra , Jason Gunthorpe , Benjamin Herrenschmidt , Paul Mackerras , "David S. Miller" , Martin Schwidefsky , Heiko Carstens , Rich Felker , Yoshinori Sato , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Ralf Baechle , James Hogan , linux-mm , Linux Kernel Mailing List , linux-mips@vger.kernel.org, linuxppc-dev , linux-s390 , Linux-sh , sparclinux@vger.kernel.org, linux-rdma@vger.kernel.org, "netdev@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Mar 17, 2019 at 7:36 PM wrote: > > From: Ira Weiny > > DAX pages were previously unprotected from longterm pins when users > called get_user_pages_fast(). > > Use the new FOLL_LONGTERM flag to check for DEVMAP pages and fall > back to regular GUP processing if a DEVMAP page is encountered. > > Signed-off-by: Ira Weiny > --- > mm/gup.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 0684a9536207..173db0c44678 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1600,6 +1600,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, > goto pte_unmap; > > if (pte_devmap(pte)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + goto pte_unmap; > + > pgmap = get_dev_pagemap(pte_pfn(pte), pgmap); > if (unlikely(!pgmap)) { > undo_dev_pagemap(nr, nr_start, pages); > @@ -1739,8 +1742,11 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, > if (!pmd_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pmd_devmap(orig)) > + if (pmd_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr); > + } > > refs = 0; > page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > @@ -1777,8 +1783,11 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, > if (!pud_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pud_devmap(orig)) > + if (pud_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr); > + } > > refs = 0; > page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); > @@ -2066,8 +2075,20 @@ int get_user_pages_fast(unsigned long start, int nr_pages, > start += nr << PAGE_SHIFT; > pages += nr; > > - ret = get_user_pages_unlocked(start, nr_pages - nr, pages, > - gup_flags); > + if (gup_flags & FOLL_LONGTERM) { > + down_read(¤t->mm->mmap_sem); > + ret = __gup_longterm_locked(current, current->mm, > + start, nr_pages - nr, > + pages, NULL, gup_flags); > + up_read(¤t->mm->mmap_sem); > + } else { > + /* > + * retain FAULT_FOLL_ALLOW_RETRY optimization if > + * possible > + */ > + ret = get_user_pages_unlocked(start, nr_pages - nr, > + pages, gup_flags); I couldn't immediately grok why this path needs to branch on FOLL_LONGTERM? Won't get_user_pages_unlocked(..., FOLL_LONGTERM) do the right thing? 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=-6.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 65EB0C43381 for ; Fri, 22 Mar 2019 22:14:38 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D96A121900 for ; Fri, 22 Mar 2019 22:14:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="Zb9Bl7Bn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D96A121900 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44Qycq5VZXzDqTZ for ; Sat, 23 Mar 2019 09:14:35 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=gmail.com (client-ip=2607:f8b0:4864:20::144; helo=mail-it1-x144.google.com; envelope-from=dan.j.williams@gmail.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="Zb9Bl7Bn"; dkim-atps=neutral Received: from mail-it1-x144.google.com (mail-it1-x144.google.com [IPv6:2607:f8b0:4864:20::144]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44QybB1LjLzDqRm for ; Sat, 23 Mar 2019 09:13:09 +1100 (AEDT) Received: by mail-it1-x144.google.com with SMTP id w18so5874216itj.4 for ; Fri, 22 Mar 2019 15:13:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VnWfr5Cz9g8Ts5McgdJK3bb2nMan4nq5nXqWONnMsfs=; b=Zb9Bl7Bn4sqZs4rM2mwfzJd7rKnn+/+6ONyGGwJqa1scMrXWXjmi9yoQBAbfMlLpgS RGV1LtFJyFJAtRyqt7x4phr5CYLMLHxyjOqtaGBIgKlABbih3LbLp5n0OYCbWIHRLaHd TTQ98w8krLJnK39QE8Dp0ik11E8+01Sgyn1wW72V9bUGSzJ08oA4QbCqRZA5AnJQLOtm o3basMsLTQYqNorbmDjd4KoyjPrND/z4P2rEoZfVYQnDMfAEdcsp9b63663QinvyZoJp HOu5mHwb07RCBU+1v7ChvrPznU5/HmjF8OEnSTsQgs+cld8MrdbVwNZKadLpnlT93nHs Yb2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VnWfr5Cz9g8Ts5McgdJK3bb2nMan4nq5nXqWONnMsfs=; b=haF7f/5l8KH4UQfTMTYH7ehoazoal1zRgYeXb9OvHn3AwkDyPRaL/nTiiPSAQ5f/nc hkeaOAtIsHG+4iBKPfO3BCkKjhO0hCKinddk3TbMsVGkU9GejS4cVW4MHxaGFIDCoOi1 e6yzb7GeWO5VFNU0GZkeRD9DjWLeKfZBLk0si6tSzA7pJrmAJS3oez7uuACdroIdjm/8 z6oQo7F7TG5RtfmkIgZIodyvoThskHQVzf4YuxeEjnCbsXDqGDhqIksaUKEa4Ge3pCcg r/5pP7jdQhT04xdE2qVMk+VQqgbrW54HayUDtbTJr0DYDRZ7Hx5VvYY5CcrRRBlckfAc 3NXw== X-Gm-Message-State: APjAAAVt490dQkcxQWZ7SEcZ8M84OQVpvrdWg3geoipOCPsLMjuCZuZa ofVtNLFsaTzZvYCXZCyvfz/wQgdjPVAqKmnXnfE= X-Google-Smtp-Source: APXvYqwPCPjaWzKVXpURWg65K5fkBoLbrluPEoFqqgn2rT6o/InM1ko8UbBUfBaLU8H/oERd+79+VhkVDmrMWUaE2i4= X-Received: by 2002:a02:c007:: with SMTP id y7mr8517902jai.1.1553292786464; Fri, 22 Mar 2019 15:13:06 -0700 (PDT) MIME-Version: 1.0 References: <20190317183438.2057-1-ira.weiny@intel.com> <20190317183438.2057-5-ira.weiny@intel.com> In-Reply-To: <20190317183438.2057-5-ira.weiny@intel.com> From: Dan Williams Date: Fri, 22 Mar 2019 15:12:55 -0700 Message-ID: Subject: Re: [RESEND 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast To: ira.weiny@intel.com Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Hocko , Linux-sh , Peter Zijlstra , James Hogan , Heiko Carstens , linux-mips@vger.kernel.org, linux-mm , Rich Felker , Paul Mackerras , sparclinux@vger.kernel.org, linux-s390 , Yoshinori Sato , linux-rdma@vger.kernel.org, Jason Gunthorpe , Ingo Molnar , John Hubbard , Borislav Petkov , Thomas Gleixner , "netdev@vger.kernel.org" , Linux Kernel Mailing List , Ralf Baechle , Martin Schwidefsky , Andrew Morton , linuxppc-dev , "David S. Miller" , "Kirill A. Shutemov" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sun, Mar 17, 2019 at 7:36 PM wrote: > > From: Ira Weiny > > DAX pages were previously unprotected from longterm pins when users > called get_user_pages_fast(). > > Use the new FOLL_LONGTERM flag to check for DEVMAP pages and fall > back to regular GUP processing if a DEVMAP page is encountered. > > Signed-off-by: Ira Weiny > --- > mm/gup.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 0684a9536207..173db0c44678 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1600,6 +1600,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, > goto pte_unmap; > > if (pte_devmap(pte)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + goto pte_unmap; > + > pgmap = get_dev_pagemap(pte_pfn(pte), pgmap); > if (unlikely(!pgmap)) { > undo_dev_pagemap(nr, nr_start, pages); > @@ -1739,8 +1742,11 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, > if (!pmd_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pmd_devmap(orig)) > + if (pmd_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr); > + } > > refs = 0; > page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > @@ -1777,8 +1783,11 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, > if (!pud_access_permitted(orig, flags & FOLL_WRITE)) > return 0; > > - if (pud_devmap(orig)) > + if (pud_devmap(orig)) { > + if (unlikely(flags & FOLL_LONGTERM)) > + return 0; > return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr); > + } > > refs = 0; > page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); > @@ -2066,8 +2075,20 @@ int get_user_pages_fast(unsigned long start, int nr_pages, > start += nr << PAGE_SHIFT; > pages += nr; > > - ret = get_user_pages_unlocked(start, nr_pages - nr, pages, > - gup_flags); > + if (gup_flags & FOLL_LONGTERM) { > + down_read(¤t->mm->mmap_sem); > + ret = __gup_longterm_locked(current, current->mm, > + start, nr_pages - nr, > + pages, NULL, gup_flags); > + up_read(¤t->mm->mmap_sem); > + } else { > + /* > + * retain FAULT_FOLL_ALLOW_RETRY optimization if > + * possible > + */ > + ret = get_user_pages_unlocked(start, nr_pages - nr, > + pages, gup_flags); I couldn't immediately grok why this path needs to branch on FOLL_LONGTERM? Won't get_user_pages_unlocked(..., FOLL_LONGTERM) do the right thing?