On Fri, Jun 17, 2016 at 03:00:00PM +0200, Michal Hocko wrote: > 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.shute...@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.shute...@linux.intel.com> > > Reported-by: zhongjiang <zhongji...@huawei.com> > > Fixes: dc6c9a35b66b ("mm: account pmd page tables to the process") > > Cc: <sta...@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().
I guess, we can live without stable backport. > > Acked-by: Michal Hocko <mho...@suse.com> Thanks. -- Kirill A. Shutemov