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 796F9C433F5 for ; Thu, 21 Apr 2022 08:12:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358214AbiDUIPh (ORCPT ); Thu, 21 Apr 2022 04:15:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357117AbiDUIPc (ORCPT ); Thu, 21 Apr 2022 04:15:32 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10BBE1F62D; Thu, 21 Apr 2022 01:12:43 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KkVdW5c14zhXYn; Thu, 21 Apr 2022 16:12:31 +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; Thu, 21 Apr 2022 16:12:40 +0800 Subject: Re: [PATCH v13 2/7] mm: factor helpers for memory_failure_dev_pagemap To: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= , Shiyang Ruan CC: "linux-kernel@vger.kernel.org" , "linux-xfs@vger.kernel.org" , "nvdimm@lists.linux.dev" , "linux-mm@kvack.org" , "linux-fsdevel@vger.kernel.org" , "djwong@kernel.org" , "dan.j.williams@intel.com" , "david@fromorbit.com" , "hch@infradead.org" , "jane.chu@oracle.com" , Christoph Hellwig References: <20220419045045.1664996-1-ruansy.fnst@fujitsu.com> <20220419045045.1664996-3-ruansy.fnst@fujitsu.com> <20220421061344.GA3607858@hori.linux.bs1.fc.nec.co.jp> From: Miaohe Lin Message-ID: <564100f4-fb8f-e2cf-db69-495294090ba4@huawei.com> Date: Thu, 21 Apr 2022 16:12:40 +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: <20220421061344.GA3607858@hori.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) 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 2022/4/21 14:13, HORIGUCHI NAOYA(堀口 直也) wrote: > On Tue, Apr 19, 2022 at 12:50:40PM +0800, Shiyang Ruan wrote: >> memory_failure_dev_pagemap code is a bit complex before introduce RMAP >> feature for fsdax. So it is needed to factor some helper functions to >> simplify these code. >> >> Signed-off-by: Shiyang Ruan >> Reviewed-by: Darrick J. Wong >> Reviewed-by: Christoph Hellwig >> Reviewed-by: Dan Williams > > Thanks for the refactoring. As I commented to 0/7, the conflict with > "mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb()" > can be trivially resolved. > > Another few comment below ... > >> --- >> mm/memory-failure.c | 157 ++++++++++++++++++++++++-------------------- >> 1 file changed, 87 insertions(+), 70 deletions(-) >> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index e3fbff5bd467..7c8c047bfdc8 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -1498,6 +1498,90 @@ static int try_to_split_thp_page(struct page *page, const char *msg) >> return 0; >> } >> >> +static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn, >> + struct address_space *mapping, pgoff_t index, int flags) >> +{ >> + struct to_kill *tk; >> + unsigned long size = 0; >> + >> + list_for_each_entry(tk, to_kill, nd) >> + if (tk->size_shift) >> + size = max(size, 1UL << tk->size_shift); >> + >> + if (size) { >> + /* >> + * Unmap the largest mapping to avoid breaking up device-dax >> + * mappings which are constant size. The actual size of the >> + * mapping being torn down is communicated in siginfo, see >> + * kill_proc() >> + */ >> + loff_t start = (index << PAGE_SHIFT) & ~(size - 1); >> + >> + unmap_mapping_range(mapping, start, size, 0); >> + } >> + >> + kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags); >> +} >> + >> +static int mf_generic_kill_procs(unsigned long long pfn, int flags, >> + struct dev_pagemap *pgmap) >> +{ >> + struct page *page = pfn_to_page(pfn); >> + LIST_HEAD(to_kill); >> + dax_entry_t cookie; >> + int rc = 0; >> + >> + /* >> + * Pages instantiated by device-dax (not filesystem-dax) >> + * may be compound pages. >> + */ >> + page = compound_head(page); >> + >> + /* >> + * Prevent the inode from being freed while we are interrogating >> + * the address_space, typically this would be handled by >> + * lock_page(), but dax pages do not use the page lock. This >> + * also prevents changes to the mapping of this pfn until >> + * poison signaling is complete. >> + */ >> + cookie = dax_lock_page(page); >> + if (!cookie) >> + return -EBUSY; >> + >> + if (hwpoison_filter(page)) { >> + rc = -EOPNOTSUPP; >> + goto unlock; >> + } >> + >> + if (pgmap->type == MEMORY_DEVICE_PRIVATE) { >> + /* >> + * TODO: Handle HMM pages which may need coordination >> + * with device-side memory. >> + */ >> + return -EBUSY; > > Don't we need to go to dax_unlock_page() as the origincal code do? I think dax_unlock_page is needed too and please remember set rc to -EBUSY before out. > >> + } >> + >> + /* >> + * Use this flag as an indication that the dax page has been >> + * remapped UC to prevent speculative consumption of poison. >> + */ >> + SetPageHWPoison(page); >> + >> + /* >> + * Unlike System-RAM there is no possibility to swap in a >> + * different physical page at a given virtual address, so all >> + * userspace consumption of ZONE_DEVICE memory necessitates >> + * SIGBUS (i.e. MF_MUST_KILL) >> + */ >> + flags |= MF_ACTION_REQUIRED | MF_MUST_KILL; >> + collect_procs(page, &to_kill, true); >> + >> + unmap_and_kill(&to_kill, pfn, page->mapping, page->index, flags); >> +unlock: >> + dax_unlock_page(page, cookie); >> + return rc; >> +} >> + >> /* >> * Called from hugetlb code with hugetlb_lock held. >> * >> @@ -1644,12 +1728,8 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags, >> struct dev_pagemap *pgmap) >> { >> struct page *page = pfn_to_page(pfn); >> - unsigned long size = 0; >> - struct to_kill *tk; >> LIST_HEAD(tokill); > > Is this variable unused in this function? There has a to_kill in mf_generic_kill_procs. So this one is unneeded. We should remove it. > > Thanks, > Naoya Horiguchi > Except for the above nit, the patch looks good to me. Thanks! Reviewed-by: Miaohe Lin