From: Michal Hocko <mhocko@kernel.org> To: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Mike Kravetz <mike.kravetz@oracle.com>, zhongjiang <zhongjiang@huawei.com>, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: fix account pmd page to the process Date: Fri, 17 Jun 2016 15:00:00 +0200 [thread overview] Message-ID: <20160617125959.GH21670@dhcp22.suse.cz> (raw) In-Reply-To: <20160617122506.GC6534@node.shutemov.name> On Fri 17-06-16 15:25:06, Kirill A. Shutemov wrote: [...] > >From fd22922e7b4664e83653a84331f0a95b985bff0c Mon Sep 17 00:00:00 2001 > From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> > Date: Fri, 17 Jun 2016 15:07:03 +0300 > Subject: [PATCH] hugetlb: fix nr_pmds accounting with shared page tables > > We account HugeTLB's shared page table to all processes who share it. > The accounting happens during huge_pmd_share(). > > If somebody populates pud entry under us, we should decrease pagetable's > refcount and decrease nr_pmds of the process. > > By mistake, I increase nr_pmds again in this case. :-/ > It will lead to "BUG: non-zero nr_pmds on freeing mm: 2" on process' > exit. > > Let's fix this by increasing nr_pmds only when we're sure that the page > table will be used. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Reported-by: zhongjiang <zhongjiang@huawei.com> > Fixes: dc6c9a35b66b ("mm: account pmd page tables to the process") > Cc: <stable@vger.kernel.org> [4.0+] Yes this patch is better. Is it worth backporting to stable though? BUG message sounds scary but it is not a real BUG(). Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/hugetlb.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index e197cd7080e6..ed6a537f0878 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4216,7 +4216,6 @@ pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) > if (saddr) { > spte = huge_pte_offset(svma->vm_mm, saddr); > if (spte) { > - mm_inc_nr_pmds(mm); > get_page(virt_to_page(spte)); > break; > } > @@ -4231,9 +4230,9 @@ 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)); > + mm_inc_nr_pmds(mm); > } else { > put_page(virt_to_page(spte)); > - mm_inc_nr_pmds(mm); > } > spin_unlock(ptl); > out: > -- > Kirill A. Shutemov -- Michal Hocko SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Mike Kravetz <mike.kravetz@oracle.com>, zhongjiang <zhongjiang@huawei.com>, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: fix account pmd page to the process Date: Fri, 17 Jun 2016 15:00:00 +0200 [thread overview] Message-ID: <20160617125959.GH21670@dhcp22.suse.cz> (raw) In-Reply-To: <20160617122506.GC6534@node.shutemov.name> On Fri 17-06-16 15:25:06, Kirill A. Shutemov wrote: [...] > >From fd22922e7b4664e83653a84331f0a95b985bff0c Mon Sep 17 00:00:00 2001 > From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> > Date: Fri, 17 Jun 2016 15:07:03 +0300 > Subject: [PATCH] hugetlb: fix nr_pmds accounting with shared page tables > > We account HugeTLB's shared page table to all processes who share it. > The accounting happens during huge_pmd_share(). > > If somebody populates pud entry under us, we should decrease pagetable's > refcount and decrease nr_pmds of the process. > > By mistake, I increase nr_pmds again in this case. :-/ > It will lead to "BUG: non-zero nr_pmds on freeing mm: 2" on process' > exit. > > Let's fix this by increasing nr_pmds only when we're sure that the page > table will be used. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Reported-by: zhongjiang <zhongjiang@huawei.com> > Fixes: dc6c9a35b66b ("mm: account pmd page tables to the process") > Cc: <stable@vger.kernel.org> [4.0+] Yes this patch is better. Is it worth backporting to stable though? BUG message sounds scary but it is not a real BUG(). Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/hugetlb.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index e197cd7080e6..ed6a537f0878 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4216,7 +4216,6 @@ pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) > if (saddr) { > spte = huge_pte_offset(svma->vm_mm, saddr); > if (spte) { > - mm_inc_nr_pmds(mm); > get_page(virt_to_page(spte)); > break; > } > @@ -4231,9 +4230,9 @@ 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)); > + mm_inc_nr_pmds(mm); > } else { > put_page(virt_to_page(spte)); > - mm_inc_nr_pmds(mm); > } > spin_unlock(ptl); > out: > -- > Kirill A. Shutemov -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-06-17 13:00 UTC|newest] Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-16 11:36 [PATCH] mm: fix account pmd page to the process zhongjiang 2016-06-16 11:36 ` zhongjiang 2016-06-16 15:42 ` Michal Hocko 2016-06-16 15:42 ` Michal Hocko 2016-06-16 15:43 ` Michal Hocko 2016-06-16 15:43 ` Michal Hocko 2016-06-16 16:05 ` Mike Kravetz 2016-06-16 16:05 ` Mike Kravetz 2016-06-16 16:31 ` Michal Hocko 2016-06-16 16:31 ` Michal Hocko 2016-06-16 16:47 ` Mike Kravetz 2016-06-16 16:47 ` Mike Kravetz 2016-06-17 12:25 ` Kirill A. Shutemov 2016-06-17 12:25 ` Kirill A. Shutemov 2016-06-17 13:00 ` Michal Hocko [this message] 2016-06-17 13:00 ` Michal Hocko 2016-06-17 14:25 ` Kirill A. Shutemov 2016-06-17 14:25 ` Kirill A. Shutemov 2016-06-17 15:39 ` Mike Kravetz 2016-06-17 15:39 ` Mike Kravetz 2016-06-18 5:07 ` zhong jiang 2016-06-18 5:07 ` zhong jiang 2016-06-17 11:18 ` zhong jiang 2016-06-17 11:18 ` zhong jiang [not found] <1466163941-12952-1-git-send-email-zhongjiang@huawei.com> 2016-06-17 12:01 ` zhong jiang 2016-06-17 12:01 ` zhong jiang -- strict thread matches above, loose matches on Subject: below -- 2016-06-17 11:56 zhongjiang 2016-06-17 11:56 ` zhongjiang 2016-06-17 12:21 ` Michal Hocko 2016-06-17 12:21 ` Michal Hocko 2016-06-17 13:04 ` zhong jiang 2016-06-17 13:04 ` zhong jiang [not found] <1466076175-23444-1-git-send-email-zhongjiang@huawei.com> 2016-06-16 11:30 ` zhong jiang 2016-06-16 11:30 ` zhong jiang 2016-06-16 11:28 zhongjiang 2016-06-16 11:28 ` zhongjiang 2016-06-16 11:17 zhongjiang 2016-06-16 11:17 ` zhongjiang 2016-06-16 11:16 zhongjiang 2016-06-16 11:16 ` zhongjiang 2016-06-16 11:13 zhongjiang 2016-06-16 11:13 ` zhongjiang 2016-06-16 7:47 zhongjiang 2016-06-16 7:47 ` zhongjiang 2016-06-15 14:48 zhongjiang
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