From 832d7aa051106c927cae05ced29d3fd31459ed21 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 29 Dec 2017 08:54:01 +0100 Subject: mm: optimize dev_pagemap reference counting around get_dev_pagemap Change the calling convention so that get_dev_pagemap always consumes the previous reference instead of doing this using an explicit earlier call to put_dev_pagemap in the callers. The callers will still need to put the final reference after finishing the loop over the pages. Signed-off-by: Christoph Hellwig Reviewed-by: Logan Gunthorpe Signed-off-by: Dan Williams --- mm/gup.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'mm/gup.c') diff --git a/mm/gup.c b/mm/gup.c index e0d82b6706d7..3affe7544b0c 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1410,7 +1410,6 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, VM_BUG_ON_PAGE(compound_head(page) != head, page); - put_dev_pagemap(pgmap); SetPageReferenced(page); pages[*nr] = page; (*nr)++; @@ -1420,6 +1419,8 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, ret = 1; pte_unmap: + if (pgmap) + put_dev_pagemap(pgmap); pte_unmap(ptem); return ret; } @@ -1459,10 +1460,12 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, SetPageReferenced(page); pages[*nr] = page; get_page(page); - put_dev_pagemap(pgmap); (*nr)++; pfn++; } while (addr += PAGE_SIZE, addr != end); + + if (pgmap) + put_dev_pagemap(pgmap); return 1; } -- cgit v1.2.3-59-g8ed1b