From nobody Wed Apr 8 06:05:16 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 AFC84C32772 for ; Tue, 23 Aug 2022 17:13:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343726AbiHWRNF (ORCPT ); Tue, 23 Aug 2022 13:13:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39022 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344937AbiHWRL3 (ORCPT ); Tue, 23 Aug 2022 13:11:29 -0400 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E633C150173 for ; Tue, 23 Aug 2022 06:58:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661263112; x=1692799112; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=4Pu50YmzN3N8F0nGXEPtFaQtALXj/wKmJ3as5yUVNsM=; b=Cg2mWjGDiDzLLB0dsiSgaCLxU6sC9HoY+NyEG8KV5K10Vkhedq/zW+NH 0/vKhvIZ8ER55gJcuAQ4OW2hnZMtOcWz6M9PkJ8yCiO5SHgJ8ksEIdQlz a9FP9uIwQ9InLHVMnBQBosgrgNp2yHoI8uammwi6v3dVLKp8p2S8GU5Zw 4X0tpbbqE3S2CkC4wvNQPlGGPlFHVX2Xrd6SkjTD7Xc75Pnp3+NzumOIf vKJdB2UIdu4RCHgLvqbYGkwyPxQox4uYFwmL8l0siAwx8ojq8+nGAh2V2 +hYe3798iyLVGBcf7swFqUOSc6hdF4RmL33WkDw3CTrAbB3I2PWLbFWLR g==; X-IronPort-AV: E=McAfee;i="6500,9779,10448"; a="357669589" X-IronPort-AV: E=Sophos;i="5.93,257,1654585200"; d="scan'208";a="357669589" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Aug 2022 06:58:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,257,1654585200"; d="scan'208";a="638663381" Received: from sse-cse-haiyue-nuc.sh.intel.com ([10.239.241.114]) by orsmga008.jf.intel.com with ESMTP; 23 Aug 2022 06:58:29 -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, mike.kravetz@oracle.com, gerald.schaefer@linux.ibm.com, Haiyue Wang , Felix Kuehling Subject: [PATCH v7 2/2] mm: fix the handling Non-LRU pages returned by follow_page Date: Tue, 23 Aug 2022 21:58:41 +0800 Message-Id: <20220823135841.934465-3-haiyue.wang@intel.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823135841.934465-1-haiyue.wang@intel.com> References: <20220823135841.934465-1-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(). Since the zone device page can't be a transparent huge page, so drop the redundant zone device page check for split_huge_pages_pid(). (by Miaohe) 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 Reviewed-by: Alistair Popple Reviewed-by: Miaohe Lin Acked-by: David Hildenbrand --- mm/huge_memory.c | 2 +- mm/ksm.c | 12 +++++++++--- mm/migrate.c | 19 ++++++++++++------- 3 files changed, 22 insertions(+), 11 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8a7c1b344abe..2ee6d38a1426 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2963,7 +2963,7 @@ static int split_huge_pages_pid(int pid, unsigned lon= g 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)) 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..44e05ce41d49 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; @@ -1868,13 +1871,15 @@ static void do_pages_stat_array(struct mm_struct *m= m, unsigned long nr_pages, if (IS_ERR(page)) goto set_status; =20 - if (page && !is_zone_device_page(page)) { + err =3D -ENOENT; + if (!page) + goto set_status; + + if (!is_zone_device_page(page)) err =3D page_to_nid(page); - if (foll_flags & FOLL_GET) - put_page(page); - } else { - err =3D -ENOENT; - } + + if (foll_flags & FOLL_GET) + put_page(page); set_status: *status =3D err; =20 --=20 2.37.2