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 867CEC25B0E for ; Mon, 15 Aug 2022 07:50:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241497AbiHOHud (ORCPT ); Mon, 15 Aug 2022 03:50:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231335AbiHOHua (ORCPT ); Mon, 15 Aug 2022 03:50:30 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8FEB5FBF for ; Mon, 15 Aug 2022 00:50:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660549829; x=1692085829; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=kmKiIT0QD7YGmmeSksRuQ1t6fRNGCZ6by4e0YIyvRd8=; b=Bq+rMHnVTvItUjJgP4nkgETRbTQveIQMuBqgk6pzBIM1I+0CTtCgn9AM wTZ21K0PgL87s2RAQzqZjWQY93hEIHL+EPLDBivC8bfYfHQcLFa8iTMxx ytFeJT+L2ak7NKxr9Sz9brFgYP2KJF6cmq6q7DHPgRkMGCkQ1G8Gl7qnK dIqDecBJLmdShkKP3ldlmUjMyDPhWWZnAZp7iLqDVLpMflzWgNTF5Gp3b 4z6W/ICRTHShMmDGI12/lo4YUR9oNTEVW1Xen1Zbod7R4IZbwLF1DuluN OpBwGDSFHBiVqGp/GAMEkh2DR9B9uPRzCZs4uBGVHoUQJRJ/V/YyV3XUF A==; X-IronPort-AV: E=McAfee;i="6400,9594,10439"; a="289481254" X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="289481254" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Aug 2022 00:50:29 -0700 X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="582798198" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Aug 2022 00:50:26 -0700 From: "Huang, Ying" To: Haiyue Wang Cc: , , , , , , , , , Felix Kuehling Subject: Re: [PATCH v5 2/2] mm: fix the handling Non-LRU pages returned by follow_page References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220815070240.470469-1-haiyue.wang@intel.com> <20220815070240.470469-3-haiyue.wang@intel.com> Date: Mon, 15 Aug 2022 15:50:23 +0800 In-Reply-To: <20220815070240.470469-3-haiyue.wang@intel.com> (Haiyue Wang's message of "Mon, 15 Aug 2022 15:02:40 +0800") Message-ID: <87czd2c5ds.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Haiyue Wang writes: > 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_pages") > Signed-off-by: Haiyue Wang LGTM, Thanks! Reviewed-by: "Huang, Ying" > --- > 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 long vaddr_start, > /* FOLL_DUMP to ignore special (like zero) pages */ > page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); > > - if (IS_ERR_OR_NULL(page) || is_zone_device_page(page)) > + if (IS_ERR_OR_NULL(page)) > continue; > > - if (!is_transparent_hugepage(page)) > + if (is_zone_device_page(page) || !is_transparent_hugepage(page)) > goto next; > > 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, unsigned long addr) > cond_resched(); > page = 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 = handle_mm_fault(vma, addr, > @@ -560,12 +560,15 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item) > goto out; > > page = 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 = NULL; > @@ -2308,11 +2311,13 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page) > if (ksm_test_exit(mm)) > break; > *page = 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 += 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(struct page **page) > mmap_read_unlock(mm); > return rmap_item; > } > +next_page: > put_page(*page); > ksm_scan.address += 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; > > err = -ENOENT; > - if (!page || is_zone_device_page(page)) > + if (!page) > goto out; > > + if (is_zone_device_page(page)) > + goto out_putpage; > + > err = 0; > if (page_to_nid(page) == 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; > > - if (page && !is_zone_device_page(page)) { > - err = page_to_nid(page); > + if (page) { > + err = !is_zone_device_page(page) ? page_to_nid(page) > + : -ENOENT; > if (foll_flags & FOLL_GET) > put_page(page); > } else {