[It seems that this patch has been sent several times and this particular copy didn't add Kirill who has added this code CC him now]
On Thu 16-06-16 17:42:14, Michal Hocko wrote: > On Thu 16-06-16 19:36:11, zhongjiang wrote: > > From: zhong jiang <[email protected]> > > > > 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 <[email protected]> > > --- > > 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? > > > + > > spin_unlock(ptl); > > out: > > pte = (pte_t *)pmd_alloc(mm, pud, addr); > > -- > > 1.8.3.1 > > -- > Michal Hocko > SUSE Labs -- Michal Hocko SUSE Labs
