From mboxrd@z Thu Jan 1 00:00:00 1970 From: ira.weiny@intel.com Date: Wed, 13 Feb 2019 23:04:52 +0000 Subject: [PATCH V2 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast Message-Id: <20190213230455.5605-5-ira.weiny@intel.com> List-Id: References: <20190211201643.7599-1-ira.weiny@intel.com> <20190213230455.5605-1-ira.weiny@intel.com> In-Reply-To: <20190213230455.5605-1-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, kvm@vger.kernel.org, linux-fpga@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, linux-scsi@vger.kernel.org, devel@driverdev.osuosl.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-fbdev@vger.kernel.org, xen-devel@lists.xenproject.org, devel@lists.orangefs.org, linux-mm@kvack.org, ceph-devel@vger.kernel.org, rds-devel@oss.oracle.com Cc: Martin Brandenburg , Rich Felker , David Hildenbrand , David Airlie , Jason Wang , =?UTF-8?q?Kai=20M=C3=A4kisara?= , Michal Hocko , Ira Weiny , Ben Chan , Rob Springer , Todd Poynor , Yoshinori Sato , "Michael S. Tsirkin" , Jason Gunthorpe , Ingo Molnar , Matt Porter , Wu Hao , Alan Tull , John Hubbard , "James E.J. Bottomley" , Alex Williamson , Stefano Stabellini , Borislav Petkov 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 | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 6f32d36b3c5b..f7e759c523bb 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1439,6 +1439,9 @@ 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); @@ -1578,8 +1581,11 @@ 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); @@ -1904,8 +1910,20 @@ 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); + } /* Have to be a bit careful with return values */ if (nr > 0) { -- 2.20.1