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Shutemov" To: Song Liu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, namit@vmware.com, peterz@infradead.org, oleg@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org, matthew.wilcox@oracle.com, kirill.shutemov@linux.intel.com, kernel-team@fb.com, william.kucharski@oracle.com, chad.mynhier@oracle.com, mike.kravetz@oracle.com Subject: Re: [PATCH uprobe, thp 1/4] mm, thp: allow preallocate pgtable for split_huge_pmd_address() Message-ID: <20190530111015.bz2om5aelsmwphwa@box> References: <20190529212049.2413886-1-songliubraving@fb.com> <20190529212049.2413886-2-songliubraving@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190529212049.2413886-2-songliubraving@fb.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 29, 2019 at 02:20:46PM -0700, Song Liu wrote: > @@ -2133,10 +2133,15 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, > VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); > VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) > && !pmd_devmap(*pmd)); > + /* only file backed vma need preallocate pgtable*/ > + VM_BUG_ON(vma_is_anonymous(vma) && prealloc_pgtable); > > count_vm_event(THP_SPLIT_PMD); > > - if (!vma_is_anonymous(vma)) { > + if (prealloc_pgtable) { > + pgtable_trans_huge_deposit(mm, pmd, prealloc_pgtable); > + mm_inc_nr_pmds(mm); > + } else if (!vma_is_anonymous(vma)) { > _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); > /* > * We are going to unmap this huge page. So Nope. This going to leak a page table for architectures where arch_needs_pgtable_deposit() is true. -- Kirill A. Shutemov