Messages in this thread Patch in this message | | | From | "Wang, Yalin" <> | Date | Tue, 2 Dec 2014 17:17:31 +0800 | Subject | [RFC] mm:add zero_page _mapcount when mapped into user space |
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This patch add/dec zero_page's _mapcount to make sure the mapcount is correct for zero_page, so that when read from /proc/kpagecount, zero_page's mapcount is also correct, userspace process like procrank can calculate PSS correctly.
Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com> --- mm/memory.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/mm/memory.c b/mm/memory.c index 3e50383..a6309c1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2198,6 +2198,7 @@ gotten: new_page = alloc_zeroed_user_highpage_movable(vma, address); if (!new_page) goto oom; + atomic_dec(&pfn_to_page(pte_pfn(orig_pte))->_mapcount); } else { new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); if (!new_page) @@ -2647,6 +2648,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, page_table = pte_offset_map_lock(mm, pmd, address, &ptl); if (!pte_none(*page_table)) goto unlock; + atomic_inc(&(pfn_to_page(my_zero_pfn(address)))->_mapcount); goto setpte; } -- 2.1.3
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