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 65A29C433EF for ; Mon, 11 Jul 2022 08:50:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230377AbiGKIuP (ORCPT ); Mon, 11 Jul 2022 04:50:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230173AbiGKIuG (ORCPT ); Mon, 11 Jul 2022 04:50:06 -0400 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E823102C for ; Mon, 11 Jul 2022 01:50:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1657529405; x=1689065405; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=k6KsRMZKO7LW82txBmvjqn++nQe1Xz6fEXzoYPfl0xs=; b=C9gY1eSJsNZxiI0Dff6IIZwVLEqiynLVocIX3xcrvOhQTX7jpc+Xzanp z59FAoB4hIZaQGDERaJeTwAsrND2UDZN4rQCayC8WW73TSsan1oICuMFN 9M08TrhCnCSmdeRSwzucDKEBXgm48vR9vno7fsmHgiy3jCpShV+hWV1T9 kz61WQD44fhch3lwJ1DLY4rdjhv5Wc/Vat50+RCf9D6sFCBxzZuLKhyrv y+/p+T+uIXKKrFnSxxfbASIZ2dktmdMHmWxY7S0KN+P13SklwGCS3Uc5r QiNcW/k3qrHFtw5HDJVdwZifNeqxqTAqOIsR5Cjh+VVfPJUf9ZQP/EkUQ Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10404"; a="284637831" X-IronPort-AV: E=Sophos;i="5.92,262,1650956400"; d="scan'208";a="284637831" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jul 2022 01:50:05 -0700 X-IronPort-AV: E=Sophos;i="5.92,262,1650956400"; d="scan'208";a="652374103" Received: from yhuang6-mobl1.sh.intel.com ([10.238.5.168]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jul 2022 01:50:03 -0700 From: Huang Ying To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Baolin Wang , Zi Yan , Yang Shi Subject: [PATCH -V2 1/7] migrate: fix syscall move_pages() return value for failure Date: Mon, 11 Jul 2022 16:49:42 +0800 Message-Id: <20220711084948.274787-2-ying.huang@intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220711084948.274787-1-ying.huang@intel.com> References: <20220711084948.274787-1-ying.huang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The return value of move_pages() syscall is incorrect when counting the remaining pages to be migrated. For example, for the following test program, " #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include #include #include #ifndef MADV_FREE #define MADV_FREE 8 /* free pages only if memory pressure */ #endif #define ONE_MB (1024 * 1024) #define MAP_SIZE (16 * ONE_MB) #define THP_SIZE (2 * ONE_MB) #define THP_MASK (THP_SIZE - 1) #define ERR_EXIT_ON(cond, msg) \ do { \ int __cond_in_macro = (cond); \ if (__cond_in_macro) \ error_exit(__cond_in_macro, (msg)); \ } while (0) void error_msg(int ret, int nr, int *status, const char *msg) { int i; fprintf(stderr, "Error: %s, ret : %d, error: %s\n", msg, ret, strerror(errno)); if (!nr) return; fprintf(stderr, "status: "); for (i = 0; i < nr; i++) fprintf(stderr, "%d ", status[i]); fprintf(stderr, "\n"); } void error_exit(int ret, const char *msg) { error_msg(ret, 0, NULL, msg); exit(1); } int page_size; bool do_vmsplice; bool do_thp; static int pipe_fds[2]; void *addr; char *pn; char *pn1; void *pages[2]; int status[2]; void prepare() { int ret; struct iovec iov; if (addr) { munmap(addr, MAP_SIZE); close(pipe_fds[0]); close(pipe_fds[1]); } ret = pipe(pipe_fds); ERR_EXIT_ON(ret, "pipe"); addr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); ERR_EXIT_ON(addr == MAP_FAILED, "mmap"); if (do_thp) { ret = madvise(addr, MAP_SIZE, MADV_HUGEPAGE); ERR_EXIT_ON(ret, "advise hugepage"); } pn = (char *)(((unsigned long)addr + THP_SIZE) & ~THP_MASK); pn1 = pn + THP_SIZE; pages[0] = pn; pages[1] = pn1; *pn = 1; if (do_vmsplice) { iov.iov_base = pn; iov.iov_len = page_size; ret = vmsplice(pipe_fds[1], &iov, 1, 0); ERR_EXIT_ON(ret < 0, "vmsplice"); } status[0] = status[1] = 1024; } void test_migrate() { int ret; int nodes[2] = { 1, 1 }; pid_t pid = getpid(); prepare(); ret = move_pages(pid, 1, pages, nodes, status, MPOL_MF_MOVE_ALL); error_msg(ret, 1, status, "move 1 page"); prepare(); ret = move_pages(pid, 2, pages, nodes, status, MPOL_MF_MOVE_ALL); error_msg(ret, 2, status, "move 2 pages, page 1 not mapped"); prepare(); *pn1 = 1; ret = move_pages(pid, 2, pages, nodes, status, MPOL_MF_MOVE_ALL); error_msg(ret, 2, status, "move 2 pages"); prepare(); *pn1 = 1; nodes[1] = 0; ret = move_pages(pid, 2, pages, nodes, status, MPOL_MF_MOVE_ALL); error_msg(ret, 2, status, "move 2 pages, page 1 to node 0"); } int main(int argc, char *argv[]) { numa_run_on_node(0); page_size = getpagesize(); test_migrate(); fprintf(stderr, "\nMake page 0 cannot be migrated:\n"); do_vmsplice = true; test_migrate(); fprintf(stderr, "\nTest THP:\n"); do_thp = true; do_vmsplice = false; test_migrate(); fprintf(stderr, "\nTHP: make page 0 cannot be migrated:\n"); do_vmsplice = true; test_migrate(); return 0; } " The output of the current kernel is, " Error: move 1 page, ret : 0, error: Success status: 1 Error: move 2 pages, page 1 not mapped, ret : 0, error: Success status: 1 -14 Error: move 2 pages, ret : 0, error: Success status: 1 1 Error: move 2 pages, page 1 to node 0, ret : 0, error: Success status: 1 0 Make page 0 cannot be migrated: Error: move 1 page, ret : 0, error: Success status: 1024 Error: move 2 pages, page 1 not mapped, ret : 1, error: Success status: 1024 -14 Error: move 2 pages, ret : 0, error: Success status: 1024 1024 Error: move 2 pages, page 1 to node 0, ret : 1, error: Success status: 1024 1024 " While the expected output is, " Error: move 1 page, ret : 0, error: Success status: 1 Error: move 2 pages, page 1 not mapped, ret : 0, error: Success status: 1 -14 Error: move 2 pages, ret : 0, error: Success status: 1 1 Error: move 2 pages, page 1 to node 0, ret : 0, error: Success status: 1 0 Make page 0 cannot be migrated: Error: move 1 page, ret : 1, error: Success status: 1024 Error: move 2 pages, page 1 not mapped, ret : 1, error: Success status: 1024 -14 Error: move 2 pages, ret : 1, error: Success status: 1024 1024 Error: move 2 pages, page 1 to node 0, ret : 2, error: Success status: 1024 1024 " Fix this via correcting the remaining pages counting. With the fix, the output for the test program as above is expected. Signed-off-by: "Huang, Ying" Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages") Cc: Baolin Wang Cc: Zi Yan Cc: Yang Shi --- mm/migrate.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 6c1ea61f39d8..472335f0aaa3 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1682,7 +1682,7 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node, * well. */ if (err > 0) - err += nr_pages - i - 1; + err += nr_pages - i; return err; } return store_status(status, start, node, i - start); @@ -1768,8 +1768,12 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, err = move_pages_and_store_status(mm, current_node, &pagelist, status, start, i, nr_pages); - if (err) + if (err) { + /* We have stored status of page i */ + if (err > 0) + err--; goto out; + } current_node = NUMA_NO_NODE; } out_flush: -- 2.30.2