From patchwork Sat Jan 4 20:59:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 234445 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 539EEC32771 for ; Sat, 4 Jan 2020 20:59:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2246224653 for ; Sat, 4 Jan 2020 20:59:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578171588; bh=/ZlR/E1jn0C9hBj0oLMKeaDnKIQNPLBFqwsD/W5qyKg=; h=Date:From:To:Subject:List-ID:From; b=lZu/bLAK4roOlYucbhWdxcoLhQ8JJuBVWSSKbBpgd2U6/tD7KfUVFAL4ljORDkLZ0 55G+sg45mgLeNf8k/CdZYH6Nox3iiSlAAfK1xybX4piVTPw5vnkbwbCoAy7GyXJAY6 j5aMbmCvIzn0UrSEQW67nOFbWgkSIVfok1SsLEmg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726281AbgADU7r (ORCPT ); Sat, 4 Jan 2020 15:59:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:36630 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726135AbgADU7r (ORCPT ); Sat, 4 Jan 2020 15:59:47 -0500 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B56C624650; Sat, 4 Jan 2020 20:59:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578171587; bh=/ZlR/E1jn0C9hBj0oLMKeaDnKIQNPLBFqwsD/W5qyKg=; h=Date:From:To:Subject:From; b=gqYps4jMlTQf2fLQpruLOM4N9yDRoYs89ER1PLGSjqV3S/PxlayZqrik5M0oSZaU/ qPGMU8gyVB5JO7M9Sq1SvPEf4mlkwRr+Myfh278K997+BblSINZXy2GjcXPG8xCgNh zL/PxnlpE4fpmmQ3AvqwfFmvc12HxgpdhhBTbv0k= Date: Sat, 04 Jan 2020 12:59:46 -0800 From: akpm@linux-foundation.org To: akpm@linux-foundation.org, cl@linux.com, fabecassis@nvidia.com, jhubbard@nvidia.com, linux-mm@kvack.org, mgorman@techsingularity.net, mhocko@suse.com, mm-commits@vger.kernel.org, stable@vger.kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, yang.shi@linux.alibaba.com Subject: [patch 05/17] mm: move_pages: return valid node id in status if the page is already on the target node Message-ID: <20200104205946.bXLvlabMj%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Yang Shi Subject: mm: move_pages: return valid node id in status if the page is already on the target node Felix Abecassis reports move_pages() would return random status if the pages are already on the target node by the below test program: ---8<--- int main(void) { const long node_id = 1; const long page_size = sysconf(_SC_PAGESIZE); const int64_t num_pages = 8; unsigned long nodemask = 1 << node_id; long ret = set_mempolicy(MPOL_BIND, &nodemask, sizeof(nodemask)); if (ret < 0) return (EXIT_FAILURE); void **pages = malloc(sizeof(void*) * num_pages); for (int i = 0; i < num_pages; ++i) { pages[i] = mmap(NULL, page_size, PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_POPULATE | MAP_ANONYMOUS, -1, 0); if (pages[i] == MAP_FAILED) return (EXIT_FAILURE); } ret = set_mempolicy(MPOL_DEFAULT, NULL, 0); if (ret < 0) return (EXIT_FAILURE); int *nodes = malloc(sizeof(int) * num_pages); int *status = malloc(sizeof(int) * num_pages); for (int i = 0; i < num_pages; ++i) { nodes[i] = node_id; status[i] = 0xd0; /* simulate garbage values */ } ret = move_pages(0, num_pages, pages, nodes, status, MPOL_MF_MOVE); printf("move_pages: %ld ", ret); for (int i = 0; i < num_pages; ++i) printf("status[%d] = %d ", i, status[i]); } ---8<--- Then running the program would return nonsense status values: $ ./move_pages_bug move_pages: 0 status[0] = 208 status[1] = 208 status[2] = 208 status[3] = 208 status[4] = 208 status[5] = 208 status[6] = 208 status[7] = 208 This is because the status is not set if the page is already on the target node, but move_pages() should return valid status as long as it succeeds. The valid status may be errno or node id. We can't simply initialize status array to zero since the pages may be not on node 0. Fix it by updating status with node id which the page is already on. Link: http://lkml.kernel.org/r/1575584353-125392-1-git-send-email-yang.shi@linux.alibaba.com Fixes: a49bd4d71637 ("mm, numa: rework do_pages_move") Signed-off-by: Yang Shi Reported-by: Felix Abecassis Tested-by: Felix Abecassis Suggested-by: Michal Hocko Reviewed-by: John Hubbard Acked-by: Christoph Lameter Acked-by: Michal Hocko Reviewed-by: Vlastimil Babka Cc: Mel Gorman Cc: [4.17+] Signed-off-by: Andrew Morton --- mm/migrate.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) --- a/mm/migrate.c~mm-move_pages-return-valid-node-id-in-status-if-the-page-is-already-on-the-target-node +++ a/mm/migrate.c @@ -1512,9 +1512,11 @@ static int do_move_pages_to_node(struct /* * Resolves the given address to a struct page, isolates it from the LRU and * puts it to the given pagelist. - * Returns -errno if the page cannot be found/isolated or 0 when it has been - * queued or the page doesn't need to be migrated because it is already on - * the target node + * Returns: + * errno - if the page cannot be found/isolated + * 0 - when it doesn't have to be migrated because it is already on the + * target node + * 1 - when it has been queued */ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, int node, struct list_head *pagelist, bool migrate_all) @@ -1553,7 +1555,7 @@ static int add_page_for_migration(struct if (PageHuge(page)) { if (PageHead(page)) { isolate_huge_page(page, pagelist); - err = 0; + err = 1; } } else { struct page *head; @@ -1563,7 +1565,7 @@ static int add_page_for_migration(struct if (err) goto out_putpage; - err = 0; + err = 1; list_add_tail(&head->lru, pagelist); mod_node_page_state(page_pgdat(head), NR_ISOLATED_ANON + page_is_file_cache(head), @@ -1640,8 +1642,17 @@ static int do_pages_move(struct mm_struc */ err = add_page_for_migration(mm, addr, current_node, &pagelist, flags & MPOL_MF_MOVE_ALL); - if (!err) + + if (!err) { + /* The page is already on the target node */ + err = store_status(status, i, current_node, 1); + if (err) + goto out_flush; continue; + } else if (err > 0) { + /* The page is successfully queued for migration */ + continue; + } err = store_status(status, i, err, 1); if (err)