From nobody Sat Apr 11 06:44:18 2026 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 F3C94C25B06 for ; Mon, 15 Aug 2022 01:59:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229990AbiHOB7H (ORCPT ); Sun, 14 Aug 2022 21:59:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229612AbiHOB67 (ORCPT ); Sun, 14 Aug 2022 21:58:59 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52CEB12AB3 for ; Sun, 14 Aug 2022 18:58:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660528738; x=1692064738; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=SnO+KuyY2Ig6pp+7jgz3mFNr913uLAxnryQVGv4z4qw=; b=hCyKHYXYhw/Nc9/CtPAHJlapN9nORTQ2LxFWoE9suBqJBwkY79N5EyWj SKye5swHEgYPUqQlUI8vkUA8Jypx0lFKdk/pqyQerAHDSN1uQY+h2q0WX yoEwZYTliRAy/HK0syn7JAsDeljz4I4GAd0O59ocV1f7GfB5dKXnyN3j0 +NKMO2kNBrJKpHioBEva5+XLU3evsr7H5HAsHR0MfK9Kch/xtoxfwg+YE C/42LTvgiJbu+QL02eAEcYAZBry/JTT3CSfn9aU6gL/GNVn4ekgdL9HME GbXxAfaix/Cn2hQu3Nhh5ZOtfc0ArElDiKVlPPZfUc33XbiW6N0HToZjL g==; X-IronPort-AV: E=McAfee;i="6400,9594,10439"; a="292667571" X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="292667571" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Aug 2022 18:58:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="557132019" Received: from sse-cse-haiyue-nuc.sh.intel.com ([10.239.241.114]) by orsmga003.jf.intel.com with ESMTP; 14 Aug 2022 18:58:55 -0700 From: Haiyue Wang To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, david@redhat.com, linmiaohe@huawei.com, ying.huang@intel.com, songmuchun@bytedance.com, naoya.horiguchi@linux.dev, alex.sierra@amd.com, Haiyue Wang Subject: [PATCH v4 1/2] mm: migration: fix the FOLL_GET failure on following huge page Date: Mon, 15 Aug 2022 09:59:08 +0800 Message-Id: <20220815015909.439623-2-haiyue.wang@intel.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815015909.439623-1-haiyue.wang@intel.com> References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220815015909.439623-1-haiyue.wang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Not all huge page APIs support FOLL_GET option, so the __NR_move_pages will fail to get the page node information for huge page. This is an temporary solution to mitigate the racing fix. After supporting follow huge page by FOLL_GET is done, this fix can be reverted safely. Fixes: 4cd614841c06 ("mm: migration: fix possible do_pages_stat_array racin= g with memory offline") Signed-off-by: Haiyue Wang --- mm/migrate.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 6a1597c92261..581dfaad9257 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1848,6 +1848,7 @@ static void do_pages_stat_array(struct mm_struct *mm,= unsigned long nr_pages, =20 for (i =3D 0; i < nr_pages; i++) { unsigned long addr =3D (unsigned long)(*pages); + unsigned int foll_flags =3D FOLL_DUMP; struct vm_area_struct *vma; struct page *page; int err =3D -EFAULT; @@ -1856,8 +1857,12 @@ static void do_pages_stat_array(struct mm_struct *mm= , unsigned long nr_pages, if (!vma) goto set_status; =20 + /* Not all huge page follow APIs support 'FOLL_GET' */ + if (!is_vm_hugetlb_page(vma)) + foll_flags |=3D FOLL_GET; + /* FOLL_DUMP to ignore special (like zero) pages */ - page =3D follow_page(vma, addr, FOLL_GET | FOLL_DUMP); + page =3D follow_page(vma, addr, foll_flags); =20 err =3D PTR_ERR(page); if (IS_ERR(page)) @@ -1865,7 +1870,8 @@ static void do_pages_stat_array(struct mm_struct *mm,= unsigned long nr_pages, =20 if (page && !is_zone_device_page(page)) { err =3D page_to_nid(page); - put_page(page); + if (foll_flags & FOLL_GET) + put_page(page); } else { err =3D -ENOENT; } --=20 2.37.2 From nobody Sat Apr 11 06:44:18 2026 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 A24B7C25B06 for ; Mon, 15 Aug 2022 01:59:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229900AbiHOB7L (ORCPT ); Sun, 14 Aug 2022 21:59:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229841AbiHOB7C (ORCPT ); Sun, 14 Aug 2022 21:59:02 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4BFF412AD7 for ; Sun, 14 Aug 2022 18:59:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660528741; x=1692064741; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=3RyMMTN/AHHSqtfx+jaKLw7DbxnmzdBDsCyu34bLAqQ=; b=NxmT7ZpyKnKhSc9llwsKGHijl029lLql0wvmcCzpQFC1k3vCcBGCqrgo IGP8/GRHIa+witpcJPSf9jxaGjwa7DdxVnVSwTqcE67xgU3jlhDu72iof p0C5MvKbNOhw/uNQwwrKvU5OspqyYpj+J7dVIP7yf0r7EBDnr9pnR/7Sq ndoMonx+VIvIKvo8d9m1QllBbvPp0Pu6Z1ayGtVb67t5lEjCbd0cJiVMz X0aSM9qTQyMJAi1pLXVntnpwMSVcDnfujWy3UOxZVXa+hYgzW4gHHzhUQ s2EO2ziMrGkoc3j1ZrufFyAYKCIV4ZQLi0kzDLetHQ+GeR2nacdfq9PDQ Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10439"; a="292667577" X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="292667577" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Aug 2022 18:59:01 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="557132038" Received: from sse-cse-haiyue-nuc.sh.intel.com ([10.239.241.114]) by orsmga003.jf.intel.com with ESMTP; 14 Aug 2022 18:58:58 -0700 From: Haiyue Wang To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, david@redhat.com, linmiaohe@huawei.com, ying.huang@intel.com, songmuchun@bytedance.com, naoya.horiguchi@linux.dev, alex.sierra@amd.com, Haiyue Wang , Alistair Popple , Felix Kuehling Subject: [PATCH v4 2/2] mm: fix the handling Non-LRU pages returned by follow_page Date: Mon, 15 Aug 2022 09:59:09 +0800 Message-Id: <20220815015909.439623-3-haiyue.wang@intel.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815015909.439623-1-haiyue.wang@intel.com> References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220815015909.439623-1-haiyue.wang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The handling Non-LRU pages returned by follow_page() jumps directly, it doesn't call put_page() to handle the reference count, since 'FOLL_GET' flag for follow_page() has get_page() called. Fix the zone device page check by handling the page reference count correctly before returning. And as David reviewed, "device pages are never PageKsm pages". Drop this zone device page check for break_ksm(). Fixes: 3218f8712d6b ("mm: handling Non-LRU pages returned by vm_normal_page= s") Signed-off-by: Haiyue Wang --- mm/huge_memory.c | 4 ++-- mm/ksm.c | 12 +++++++++--- mm/migrate.c | 10 +++++++--- 3 files changed, 18 insertions(+), 8 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8a7c1b344abe..b2ba17c3dcd7 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2963,10 +2963,10 @@ static int split_huge_pages_pid(int pid, unsigned l= ong vaddr_start, /* FOLL_DUMP to ignore special (like zero) pages */ page =3D follow_page(vma, addr, FOLL_GET | FOLL_DUMP); =20 - if (IS_ERR_OR_NULL(page) || is_zone_device_page(page)) + if (IS_ERR_OR_NULL(page)) continue; =20 - if (!is_transparent_hugepage(page)) + if (is_zone_device_page(page) || !is_transparent_hugepage(page)) goto next; =20 total++; diff --git a/mm/ksm.c b/mm/ksm.c index 42ab153335a2..e26f57fc1f0e 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -475,7 +475,7 @@ static int break_ksm(struct vm_area_struct *vma, unsign= ed long addr) cond_resched(); page =3D follow_page(vma, addr, FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE); - if (IS_ERR_OR_NULL(page) || is_zone_device_page(page)) + if (IS_ERR_OR_NULL(page)) break; if (PageKsm(page)) ret =3D handle_mm_fault(vma, addr, @@ -560,12 +560,15 @@ static struct page *get_mergeable_page(struct rmap_it= em *rmap_item) goto out; =20 page =3D follow_page(vma, addr, FOLL_GET); - if (IS_ERR_OR_NULL(page) || is_zone_device_page(page)) + if (IS_ERR_OR_NULL(page)) goto out; + if (is_zone_device_page(page)) + goto out_putpage; if (PageAnon(page)) { flush_anon_page(vma, page, addr); flush_dcache_page(page); } else { +out_putpage: put_page(page); out: page =3D NULL; @@ -2308,11 +2311,13 @@ static struct rmap_item *scan_get_next_rmap_item(st= ruct page **page) if (ksm_test_exit(mm)) break; *page =3D follow_page(vma, ksm_scan.address, FOLL_GET); - if (IS_ERR_OR_NULL(*page) || is_zone_device_page(*page)) { + if (IS_ERR_OR_NULL(*page)) { ksm_scan.address +=3D PAGE_SIZE; cond_resched(); continue; } + if (is_zone_device_page(*page)) + goto next_page; if (PageAnon(*page)) { flush_anon_page(vma, *page, ksm_scan.address); flush_dcache_page(*page); @@ -2327,6 +2332,7 @@ static struct rmap_item *scan_get_next_rmap_item(stru= ct page **page) mmap_read_unlock(mm); return rmap_item; } +next_page: put_page(*page); ksm_scan.address +=3D PAGE_SIZE; cond_resched(); diff --git a/mm/migrate.c b/mm/migrate.c index 581dfaad9257..fee12cd2f294 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1672,9 +1672,12 @@ static int add_page_for_migration(struct mm_struct *= mm, unsigned long addr, goto out; =20 err =3D -ENOENT; - if (!page || is_zone_device_page(page)) + if (!page) goto out; =20 + if (is_zone_device_page(page)) + goto out_putpage; + err =3D 0; if (page_to_nid(page) =3D=3D node) goto out_putpage; @@ -1868,8 +1871,9 @@ static void do_pages_stat_array(struct mm_struct *mm,= unsigned long nr_pages, if (IS_ERR(page)) goto set_status; =20 - if (page && !is_zone_device_page(page)) { - err =3D page_to_nid(page); + if (page) { + err =3D !is_zone_device_page(page) ? page_to_nid(page) + : -ENOENT; if (foll_flags & FOLL_GET) put_page(page); } else { --=20 2.37.2