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authorChristoph Hellwig <hch@lst.de>2017-12-29 08:54:01 +0100
committerDan Williams <dan.j.williams@intel.com>2018-01-08 11:46:23 -0800
commit832d7aa051106c927cae05ced29d3fd31459ed21 (patch)
tree72b34c8b3ae395aedaf444246073791ab20ea3c1 /mm/gup.c
parent0822acb86cf340cd45b3af6436cec7e3bb24ebd2 (diff)
downloadlinux-832d7aa051106c927cae05ced29d3fd31459ed21.tar.bz2
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 <hch@lst.de> Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c7
1 files changed, 5 insertions, 2 deletions
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;
}