| Date | Fri, 15 May 2015 09:44:17 +0200 | From | Vlastimil Babka <> | Subject | Re: [PATCHv5 03/28] memcg: adjust to support new THP refcounting |
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On 04/23/2015 11:03 PM, Kirill A. Shutemov wrote: > As with rmap, with new refcounting we cannot rely on PageTransHuge() to > check if we need to charge size of huge page form the cgroup. We need to > get information from caller to know whether it was mapped with PMD or > PTE. > > We do uncharge when last reference on the page gone. At that point if we > see PageTransHuge() it means we need to unchange whole huge page. > > The tricky part is partial unmap -- when we try to unmap part of huge > page. We don't do a special handing of this situation, meaning we don't > uncharge the part of huge page unless last user is gone or > split_huge_page() is triggered. In case of cgroup memory pressure > happens the partial unmapped page will be split through shrinker. This > should be good enough. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Tested-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
But same question about whether it should be using hpage_nr_pages() instead of a constant.
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