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[134.134.136.100]) by mx.google.com with ESMTPS id 31si22686092plb.39.2019.03.28.09.45.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Mar 2019 09:45:38 -0700 (PDT) Received-SPF: pass (google.com: domain of ira.weiny@intel.com designates 134.134.136.100 as permitted sender) client-ip=134.134.136.100; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ira.weiny@intel.com designates 134.134.136.100 as permitted sender) smtp.mailfrom=ira.weiny@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Mar 2019 09:45:36 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,281,1549958400"; d="scan'208";a="218460206" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by orsmga001.jf.intel.com with ESMTP; 28 Mar 2019 09:45:37 -0700 From: ira.weiny@intel.com To: 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 Cc: Ira Weiny , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH V3 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast Date: Thu, 28 Mar 2019 01:44:19 -0700 Message-Id: <20190328084422.29911-5-ira.weiny@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190328084422.29911-1-ira.weiny@intel.com> References: <20190328084422.29911-1-ira.weiny@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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: 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 --- Changes from V2: Add comment on special use case of FOLL_LONGTERM mm/gup.c | 40 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 36 insertions(+), 4 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 0fa7244d6f19..567bd1b295f0 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1613,6 +1613,9 @@ 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); @@ -1752,8 +1755,11 @@ 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); @@ -1790,8 +1796,11 @@ 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); @@ -2034,6 +2043,29 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, return nr; } +static int __gup_longterm_unlocked(unsigned long start, int nr_pages, + unsigned int gup_flags, struct page **pages) +{ + int ret; + + /* + * FIXME: FOLL_LONGTERM does not work with + * get_user_pages_unlocked() (see comments in that function) + */ + if (gup_flags & FOLL_LONGTERM) { + down_read(¤t->mm->mmap_sem); + ret = __gup_longterm_locked(current, current->mm, + start, nr_pages, + pages, NULL, gup_flags); + up_read(¤t->mm->mmap_sem); + } else { + ret = get_user_pages_unlocked(start, nr_pages, + pages, gup_flags); + } + + return ret; +} + /** * get_user_pages_fast() - pin user pages in memory * @start: starting user address @@ -2079,8 +2111,8 @@ 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); + ret = __gup_longterm_unlocked(start, nr_pages - nr, + gup_flags, pages); /* Have to be a bit careful with return values */ if (nr > 0) { -- 2.20.1