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 06188C43334 for ; Tue, 7 Jun 2022 14:11:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245163AbiFGOLg (ORCPT ); Tue, 7 Jun 2022 10:11:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245081AbiFGOLb (ORCPT ); Tue, 7 Jun 2022 10:11:31 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B99EAE241 for ; Tue, 7 Jun 2022 07:11:28 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4LHXKt0T6Yz1KDBV; Tue, 7 Jun 2022 22:09:38 +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; Tue, 7 Jun 2022 22:11:25 +0800 Subject: Re: [PATCH v1 5/5] mm, hwpoison: enable memory error handling on 1GB hugepage To: Naoya Horiguchi CC: Andrew Morton , David Hildenbrand , Mike Kravetz , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , Naoya Horiguchi , , Linux-MM References: <20220602050631.771414-1-naoya.horiguchi@linux.dev> <20220602050631.771414-6-naoya.horiguchi@linux.dev> From: Miaohe Lin Message-ID: Date: Tue, 7 Jun 2022 22:11:24 +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: <20220602050631.771414-6-naoya.horiguchi@linux.dev> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) 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 2022/6/2 13:06, Naoya Horiguchi wrote: > From: Naoya Horiguchi > > Now error handling code is prepared, so remove the blocking code and > enable memory error handling on 1GB hugepage. > I'm nervous about this change. It seems there are many code paths not awared of pud swap entry. I browsed some of them: apply_to_pud_range called from apply_to_page_range: apply_to_pud_range: next = pud_addr_end(addr, end); if (pud_none(*pud) && !create) continue; if (WARN_ON_ONCE(pud_leaf(*pud))) return -EINVAL; if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) { if (!create) continue; pud_clear_bad(pud); } err = apply_to_pmd_range(mm, pud, addr, next, fn, data, create, mask); For !pud_present case, it will mostly reach apply_to_pmd_range and call pmd_offset on it. And invalid pointer will be de-referenced. Another example might be copy_pud_range and so on. So I think it might not be prepared to enable the 1GB hugepage or all of these places should be fixed? Thanks! > Signed-off-by: Naoya Horiguchi > --- > include/linux/mm.h | 1 - > include/ras/ras_event.h | 1 - > mm/memory-failure.c | 16 ---------------- > 3 files changed, 18 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 04de0c3e4f9f..58a6aa916e4f 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3238,7 +3238,6 @@ enum mf_action_page_type { > MF_MSG_DIFFERENT_COMPOUND, > MF_MSG_HUGE, > MF_MSG_FREE_HUGE, > - MF_MSG_NON_PMD_HUGE, > MF_MSG_UNMAP_FAILED, > MF_MSG_DIRTY_SWAPCACHE, > MF_MSG_CLEAN_SWAPCACHE, > diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h > index d0337a41141c..cbd3ddd7c33d 100644 > --- a/include/ras/ras_event.h > +++ b/include/ras/ras_event.h > @@ -360,7 +360,6 @@ TRACE_EVENT(aer_event, > EM ( MF_MSG_DIFFERENT_COMPOUND, "different compound page after locking" ) \ > EM ( MF_MSG_HUGE, "huge page" ) \ > EM ( MF_MSG_FREE_HUGE, "free huge page" ) \ > - EM ( MF_MSG_NON_PMD_HUGE, "non-pmd-sized huge page" ) \ > EM ( MF_MSG_UNMAP_FAILED, "unmapping failed page" ) \ > EM ( MF_MSG_DIRTY_SWAPCACHE, "dirty swapcache page" ) \ > EM ( MF_MSG_CLEAN_SWAPCACHE, "clean swapcache page" ) \ > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index babeb34f7477..ced033a99e19 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -725,7 +725,6 @@ static const char * const action_page_types[] = { > [MF_MSG_DIFFERENT_COMPOUND] = "different compound page after locking", > [MF_MSG_HUGE] = "huge page", > [MF_MSG_FREE_HUGE] = "free huge page", > - [MF_MSG_NON_PMD_HUGE] = "non-pmd-sized huge page", > [MF_MSG_UNMAP_FAILED] = "unmapping failed page", > [MF_MSG_DIRTY_SWAPCACHE] = "dirty swapcache page", > [MF_MSG_CLEAN_SWAPCACHE] = "clean swapcache page", > @@ -1614,21 +1613,6 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb > > page_flags = head->flags; > > - /* > - * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so > - * simply disable it. In order to make it work properly, we need > - * make sure that: > - * - conversion of a pud that maps an error hugetlb into hwpoison > - * entry properly works, and > - * - other mm code walking over page table is aware of pud-aligned > - * hwpoison entries. > - */ > - if (huge_page_size(page_hstate(head)) > PMD_SIZE) { > - action_result(pfn, MF_MSG_NON_PMD_HUGE, MF_IGNORED); > - res = -EBUSY; > - goto out; > - } > - > if (!hwpoison_user_mappings(p, pfn, flags, head)) { > action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED); > res = -EBUSY; >