From nobody Sat Apr 11 08:11:55 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 69C61C00140 for ; Mon, 15 Aug 2022 07:02:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241287AbiHOHCi (ORCPT ); Mon, 15 Aug 2022 03:02:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241275AbiHOHCe (ORCPT ); Mon, 15 Aug 2022 03:02:34 -0400 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4D3A1C135 for ; Mon, 15 Aug 2022 00:02:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660546953; x=1692082953; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=3RyMMTN/AHHSqtfx+jaKLw7DbxnmzdBDsCyu34bLAqQ=; b=FxGtrw/rENG96QOw9t3WWxrBRVP5IhFCBQ94iZOAbBKpNbh7z1eAk/ER 62UOs4w9Cv6h66M/pla9IlWi2NdT6xODypBu7ssQ08pJbplDlgtBoCzCk zDivy1fW3lj5ljQMBRHB1mDls+y2EnrLYm1tfjXVo+OTHElp+WAaXSL1D cCsjnZ8/YOmNUmDQXFnB8fQiEKZtOY/Er1JsIzKZimM8Y99wvPg5zUSdt 5RO/LURgDQAUEvEV4eeoHwrQAS6uValmBDHikLFV/VuEnz+Xu6/oqVGCd tSSRTRzrwQ/M4Oh8kobFmPYFzGI9+moQRQSAu6oI2r4+GNlcDWBg14k/e Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10439"; a="274960263" X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="274960263" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Aug 2022 00:02:33 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="666566780" Received: from sse-cse-haiyue-nuc.sh.intel.com ([10.239.241.114]) by fmsmga008.fm.intel.com with ESMTP; 15 Aug 2022 00:02:30 -0700 From: Haiyue Wang To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, david@redhat.com, apopple@nvidia.com, linmiaohe@huawei.com, ying.huang@intel.com, songmuchun@bytedance.com, naoya.horiguchi@linux.dev, alex.sierra@amd.com, Haiyue Wang , Felix Kuehling Subject: [PATCH v5 2/2] mm: fix the handling Non-LRU pages returned by follow_page Date: Mon, 15 Aug 2022 15:02:40 +0800 Message-Id: <20220815070240.470469-3-haiyue.wang@intel.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815070240.470469-1-haiyue.wang@intel.com> References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220815070240.470469-1-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 Reviewed-by: "Huang, Ying" Reviewed-by: Felix Kuehling --- 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