From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FA3EC19F2A for ; Fri, 29 Jul 2022 02:02:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233850AbiG2CCz (ORCPT ); Thu, 28 Jul 2022 22:02:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233460AbiG2CCx (ORCPT ); Thu, 28 Jul 2022 22:02:53 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A362E78DF3 for ; Thu, 28 Jul 2022 19:02:51 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4Lv9gt3dSqz1M8Yb; Fri, 29 Jul 2022 09:59:54 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 29 Jul 2022 10:02:48 +0800 Subject: Re: [RFC PATCH v4 7/8] hugetlb: create hugetlb_unmap_file_folio to unmap single file folio To: Mike Kravetz , , CC: Muchun Song , Michal Hocko , Peter Xu , Naoya Horiguchi , David Hildenbrand , "Aneesh Kumar K . V" , Andrea Arcangeli , "Kirill A . Shutemov" , Davidlohr Bueso , Prakash Sangappa , James Houghton , Mina Almasry , Pasha Tatashin , Axel Rasmussen , Ray Fucillo , Andrew Morton References: <20220706202347.95150-1-mike.kravetz@oracle.com> <20220706202347.95150-8-mike.kravetz@oracle.com> From: Miaohe Lin Message-ID: <3557d5a9-231c-4007-3e7e-5a7bf34ecaa8@huawei.com> Date: Fri, 29 Jul 2022 10:02:48 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220706202347.95150-8-mike.kravetz@oracle.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/7/7 4:23, Mike Kravetz wrote: > Create the new routine hugetlb_unmap_file_folio that will unmap a single > file folio. This is refactored code from hugetlb_vmdelete_list. It is > modified to do locking within the routine itself and check whether the > page is mapped within a specific vma before unmapping. > > This refactoring will be put to use and expanded upon in a subsequent > patch adding vma specific locking. > > Signed-off-by: Mike Kravetz > --- > fs/hugetlbfs/inode.c | 124 +++++++++++++++++++++++++++++++++---------- > 1 file changed, 95 insertions(+), 29 deletions(-) > > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c > index 31bd4325fce5..0eac0ea2a245 100644 > --- a/fs/hugetlbfs/inode.c > +++ b/fs/hugetlbfs/inode.c > @@ -396,6 +396,94 @@ static int hugetlbfs_write_end(struct file *file, struct address_space *mapping, > return -EINVAL; > } > > +/* > + * Called with i_mmap_rwsem held for inode based vma maps. This makes > + * sure vma (and vm_mm) will not go away. We also hold the hugetlb fault > + * mutex for the page in the mapping. So, we can not race with page being > + * faulted into the vma. > + */ > +static bool hugetlb_vma_maps_page(struct vm_area_struct *vma, > + unsigned long addr, struct page *page) > +{ > + pte_t *ptep, pte; > + > + ptep = huge_pte_offset(vma->vm_mm, addr, > + huge_page_size(hstate_vma(vma))); > + > + if (!ptep) > + return false; > + > + pte = huge_ptep_get(ptep); > + if (huge_pte_none(pte) || !pte_present(pte)) > + return false; > + > + if (pte_page(pte) == page) > + return true; > + > + return false; /* WTH??? */ I'm sorry but what does WTH means? IIUC, this could happen if pte_page is a COW-ed private page? vma_interval_tree_foreach doesn't exclude the private mapping even after cow? Except from above (trivial one), this patch looks good to me. Thanks.