| From | "Kirill A. Shutemov" <> | Subject | RE: [PATCH 03/36] memcg: adjust to support new THP refcounting | Date | Tue, 14 Jul 2015 16:58:42 +0300 (EEST) |
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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>
checkpatch fixlet:
diff --git a/mm/swapfile.c b/mm/swapfile.c index 6dd365d1c488..117bedd02db2 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1103,8 +1103,8 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, if (unlikely(!page)) return -ENOMEM; - if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false)) - { + if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, + &memcg, false)) { ret = -ENOMEM; goto out_nolock; }
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