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H A D | hugetlb.c | c17b1f42 Fri Jun 24 16:49:51 CDT 2016 Kirill A. Shutemov <kirill.shutemov@linux.intel.com> 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.
Link: http://lkml.kernel.org/r/20160617122506.GC6534@node.shutemov.name Fixes: dc6c9a35b66b ("mm: account pmd page tables to the process") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: zhongjiang <zhongjiang@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> c17b1f42 Fri Jun 24 16:49:51 CDT 2016 Kirill A. Shutemov <kirill.shutemov@linux.intel.com> 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. Link: http://lkml.kernel.org/r/20160617122506.GC6534@node.shutemov.name Fixes: dc6c9a35b66b ("mm: account pmd page tables to the process") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: zhongjiang <zhongjiang@huawei.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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