Messages in this thread | | | Date | Fri, 17 Jun 2016 19:18:29 +0800 | From | zhong jiang <> | Subject | Re: [PATCH] mm: fix account pmd page to the process |
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On 2016/6/16 23:42, Michal Hocko wrote: > On Thu 16-06-16 19:36:11, zhongjiang wrote: >> From: zhong jiang <zhongjiang@huawei.com> >> >> when a process acquire a pmd table shared by other process, we >> increase the account to current process. otherwise, a race result >> in other tasks have set the pud entry. so it no need to increase it. >> >> Signed-off-by: zhong jiang <zhongjiang@huawei.com> >> --- >> mm/hugetlb.c | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index 19d0d08..3b025c5 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -4189,10 +4189,9 @@ pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) >> if (pud_none(*pud)) { >> pud_populate(mm, pud, >> (pmd_t *)((unsigned long)spte & PAGE_MASK)); >> - } else { >> + } else >> put_page(virt_to_page(spte)); >> - mm_inc_nr_pmds(mm); >> - } > The code is quite puzzling but is this correct? Shouldn't we rather do > mm_dec_nr_pmds(mm) in that path to undo the previous inc? Yes, you are right. I will modify it in V2.
Thanks zhongjiang > >> + >> spin_unlock(ptl); >> out: >> pte = (pte_t *)pmd_alloc(mm, pud, addr); >> -- >> 1.8.3.1
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