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Date: Wed, 13 Feb 2019 15:04:52 -0800 From: ira.weiny@...el.com To: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org, kvm-ppc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org, linux-sh@...r.kernel.org, sparclinux@...r.kernel.org, kvm@...r.kernel.org, linux-fpga@...r.kernel.org, dri-devel@...ts.freedesktop.org, linux-rdma@...r.kernel.org, linux-media@...r.kernel.org, linux-scsi@...r.kernel.org, devel@...verdev.osuosl.org, virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org, linux-fbdev@...r.kernel.org, xen-devel@...ts.xenproject.org, devel@...ts.orangefs.org, linux-mm@...ck.org, ceph-devel@...r.kernel.org, rds-devel@....oracle.com Cc: Ira Weiny <ira.weiny@...el.com>, John Hubbard <jhubbard@...dia.com>, David Hildenbrand <david@...hat.com>, Cornelia Huck <cohuck@...hat.com>, Yoshinori Sato <ysato@...rs.sourceforge.jp>, Rich Felker <dalias@...c.org>, "David S. Miller" <davem@...emloft.net>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Joerg Roedel <joro@...tes.org>, Wu Hao <hao.wu@...el.com>, Alan Tull <atull@...nel.org>, Moritz Fischer <mdf@...nel.org>, David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>, Jason Gunthorpe <jgg@...pe.ca>, Dennis Dalessandro <dennis.dalessandro@...el.com>, Christian Benvenuti <benve@...co.com>, Mauro Carvalho Chehab <mchehab@...nel.org>, Matt Porter <mporter@...nel.crashing.org>, Alexandre Bounine <alex.bou9@...il.com>, Kai Mäkisara <Kai.Makisara@...umbus.fi>, "James E.J. Bottomley" <jejb@...ux.ibm.com>, "Martin K. Petersen" <martin.petersen@...cle.com>, Rob Springer <rspringer@...gle.com>, Todd Poynor <toddpoynor@...gle.com>, Ben Chan <benchan@...omium.org>, Jens Wiklander <jens.wiklander@...aro.org>, Alex Williamson <alex.williamson@...hat.com>, "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>, Stefano Stabellini <sstabellini@...nel.org>, Martin Brandenburg <martin@...ibond.com>, Peter Zijlstra <peterz@...radead.org>, Alexander Viro <viro@...iv.linux.org.uk>, Andrew Morton <akpm@...ux-foundation.org>, Michal Hocko <mhocko@...e.com>, "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> Subject: [PATCH V2 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast From: Ira Weiny <ira.weiny@...el.com> 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 <ira.weiny@...el.com> --- 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
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