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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EFF01105F7A6 for ; Fri, 13 Mar 2026 14:48:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2F5616B0089; Fri, 13 Mar 2026 10:48:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2A2836B008A; Fri, 13 Mar 2026 10:48:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 15ADB6B008C; Fri, 13 Mar 2026 10:48:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 0098D6B0089 for ; Fri, 13 Mar 2026 10:48:09 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 36BDD1A01A2 for ; Fri, 13 Mar 2026 14:48:09 +0000 (UTC) X-FDA: 84541319898.16.A281128 Received: from BL2PR02CU003.outbound.protection.outlook.com (mail-eastusazon11011063.outbound.protection.outlook.com [52.101.52.63]) by imf26.hostedemail.com (Postfix) with ESMTP id 6DFA2140007 for ; Fri, 13 Mar 2026 14:48:06 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=hdTeKSM6; arc=pass ("microsoft.com:s=arcselector10001:i=1"); spf=pass (imf26.hostedemail.com: domain of ziy@nvidia.com designates 52.101.52.63 as permitted sender) smtp.mailfrom=ziy@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1773413286; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:in-reply-to: references:dkim-signature; bh=vTsn/sGxy3VhvyNFRDl2s/shBd/Rh8rS7DndZaULMTg=; b=udIsYT2H7uMGUKTzAaxr1wcDb1Hza7424jHuD9KzkX5Dm+VB7YcyKhz9Uv+IiXr7rnqLwV bWnOO5O0zzXeT/RATSYk9qawL+p+dZ9CW9W3tVbHwqL2C8dkVHfgPgcQREzAFfqJVqF2Fh 2YOMRrybxwfcry4vt3wp8/RTB5c6EZA= ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1773413286; a=rsa-sha256; cv=pass; b=xvZBe5NrOLUY1P/28wCxuyjqOLhYB3mQaUbb4Ex4u1jBoafSr3SUeDM2w0pCmzEitUMsdh nPyyLxSnCGl0d1DHfIYTIOf2s0kiWBVVSJ8+aDZiDvLcixSxDyu223J1AJ0OLfU9mQoezk dwC4+5OV6zU0jK7LEIKmNKMR1QEFq3c= ARC-Authentication-Results: i=2; imf26.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=hdTeKSM6; arc=pass ("microsoft.com:s=arcselector10001:i=1"); spf=pass (imf26.hostedemail.com: domain of ziy@nvidia.com designates 52.101.52.63 as permitted sender) smtp.mailfrom=ziy@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=RbXv+indq5mPcHZGszIF7GZMqcsgd1jKSZmZsnHvbFSMUgyHvLpOjswPxa+9+JRSJ1E92HNDTUI1Ec+XJ0qSbxy6mYsnxN3MKt03AQBmpq3istpiShzhtpoSzTKNfcw3LcGzoNTkXzoMqbMRAQtXtbNEhWL03srCTFPnrL5ntOPPw9bEFmzeuknHdJiq9YQXlRof5PUne/o+NglFY+cXVtqtgnbOLNOiAIHJCnWTE9LUHh8SJLXTJsP1I1MF8aRGG5OpbTPVCTjGSoriKjiLD0H9SO7i2rA57j/03DVwegovR/8L+mPNc9zEiG7t+iDU8GxzfkpM1liF4jrqOEjCxg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=vTsn/sGxy3VhvyNFRDl2s/shBd/Rh8rS7DndZaULMTg=; b=UB7HHWMHWFuY5ibaOCO9k8HgdU8Rg3G9aUjKMDfRjnLJQ4jwkvfEiQw7uYXCHe5Xhjo/WMyHgtWV/sAzJ2f6zBxOj3k1CYz3HfMPAVtohdY4PZptSw1COiOZvoPtXF1X+LITt7kEtaGWJY+8v0jHWiygxY/AriY6bsihO1xjSyr0I36Qq+o6gpzGmMwwhcmgWK05bpadUJlZzf/wrfSdEbf8c4z510zeOEyYCV/LUC+63BLWjXkDw3GHkSWBZEEg8bi5Om/gZURdptuSho5Za/CF3Bptkogwq40/czx7GH67Yaa9Sek/zv5BlDe9OPDGmL3o8aR7MG11R+UEBP7lqg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=vTsn/sGxy3VhvyNFRDl2s/shBd/Rh8rS7DndZaULMTg=; b=hdTeKSM6/BUa9GW/LdVvRP8wfJZVzcCB/ki69F0yU0F+J4oLf0/4Hfq785FH+T6HgFTmNbErRPNVs+2mBYibEHH7rln+IdmfDHhOFyUpukdk4geJWV4jpKKkWh6pPAEubS/xE8sROPQcSmPugfIJMuoUpkkKOCp4WG+9qj4mbe3QwNKaH1KlU6YbGP3+5wj5Bv2j6G8CrMJRnX5oTnkSfg9+GWhAClfG3d/iQ0y47/0oYCzxJAnyxWUqs+RC5EKWnvJDxyu5+5aQ/bUnEs0CqUexL0OYgJCN0f8/AluQ1J7lRkM6uk1IgcoywMM54Za/Jvg3DqDHU3ofgLqWsy3sKg== Received: from DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) by BL1PR12MB5778.namprd12.prod.outlook.com (2603:10b6:208:391::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9723.8; Fri, 13 Mar 2026 14:47:58 +0000 Received: from DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::f01d:73d2:2dda:c7b2]) by DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::f01d:73d2:2dda:c7b2%4]) with mapi id 15.20.9723.000; Fri, 13 Mar 2026 14:47:58 +0000 From: Zi Yan To: Andrew Morton Cc: David Hildenbrand , Lorenzo Stoakes , Zi Yan , Hugh Dickins , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Matthew Wilcox , Bas van Dijk , Eero Kelly , Andrew Battat , Adam Bratschi-Kaye , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH] selftests/mm: add folio_split() and filemap_get_entry() race test Date: Fri, 13 Mar 2026 07:40:37 -0400 Message-ID: <20260313114037.3593642-1-ziy@nvidia.com> X-Mailer: git-send-email 2.51.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: BN9PR03CA0685.namprd03.prod.outlook.com (2603:10b6:408:10e::30) To DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB9473:EE_|BL1PR12MB5778:EE_ X-MS-Office365-Filtering-Correlation-Id: 876ab29e-f9cb-4a48-6250-08de810f8477 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|7416014|366016|18002099003|56012099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR12MB9473.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(7416014)(366016)(18002099003)(56012099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?wbS4vfCXHlXcK/HcCQULzImBmp4KynYKPqXMttapETWvZaE6p7/eVivh50Eh?= =?us-ascii?Q?wP0kWG2TcuPwhEYSkF+wrX47IpZT4dhH2krNuv+jowB4jUkOBGodIwW4HJYD?= =?us-ascii?Q?c5tGzT1GNJdobNyHFVC0BEYpvEXleyIpr0+LIg1sFOerkHkcyn/DIL0oEqdO?= =?us-ascii?Q?q9vehCq5K4Yc1dYOtJAfBkl+9FSGzyKfKdMHb2QyR1bruaYgxymZyrXN/p7x?= =?us-ascii?Q?Dy1PxRWu0Axn8uHRqktQc9X+6EOG7WfdEmcw8ZmU9Nonj8LrOP7iZs+BGrtx?= =?us-ascii?Q?blivTCOeoQiPWhR2MTHrLdFabca/xLocvl4EWAEEgS/Fjr2V9vfD8GXU/JIN?= =?us-ascii?Q?tRuIC/jyOqIqEHVEUEmoGffFZK/BPVaYSBjZyc3pZn5NQr1AbFqNs3W1sJ6c?= =?us-ascii?Q?HnedxyDcTYEKroQUjdwVAJDHB3a5fdpCnGfvlFWpYNy1gldvwaCOeiO0UqPs?= =?us-ascii?Q?ML1mtS7s3c2LKCObd1a/sRZmtO4fpmRH59AUvSeqkGKvGTzfa2+8OXQTHonT?= =?us-ascii?Q?QAEL2hpc8HSecIrVVwyWMxYTgsEOjkyLVSlAICOwaVJ87vryyWN2OFaFbM0x?= =?us-ascii?Q?oO2qp86R+u7Hvcl8U7g+AW5w0HzIq4Qw2NkkuZhbL9lPpMWEUZMYcU213YGM?= =?us-ascii?Q?QQiPhBmKpifuSZCIWlJBQChDn9+/zrtN5X3o+Uq4pRMTrEci16psDS1KULyG?= =?us-ascii?Q?29CnSV/2Rs4WsBWeunVuQa9uAzYQTyeaqepPC8xxyeqX2AHZm1b2YC/o0/SA?= =?us-ascii?Q?UAOUUSKTvd0kKV08TzVpBBM66v4ptwYb5dQDOO8AP0bdfpFkjbXgnsFA0SJ/?= =?us-ascii?Q?U/Pth2mE3xpxnpQaRUQ7fFh4IdV28g0PB0whLNArulCE3aLZNWzbwt4XIU2a?= =?us-ascii?Q?Rcy8AKmwwMcG4gDMzG11afoAp3Etyt8jvPSbRii9Qc9CuIZG55WOsb34yHEs?= =?us-ascii?Q?40raSbvAUXwGScr3rlJqBsOZnLj66gBAYtefAJKOOcWfUrEuUsw5hf8zeaf1?= =?us-ascii?Q?ZV984E5XCon9/UObMy53qCm2q5Hjn11xwiwUHcC8EisGER2jw+Qhd7MnY1Z1?= =?us-ascii?Q?HLv0cq0n1MLko4X1PuQLg4ZwZAJFLpU5v9O9TNAZ6Vhvagasb/RCUzqjWEkx?= =?us-ascii?Q?R3+9dBP8vO6oR1bTWOhsToGMqXP4w0JBkiTvPD1O99m70usJjEUdhSNn9HZA?= =?us-ascii?Q?FYPxle6IpS5HznNppnPLOCKQRbL8WHhC8Z+hnv00TrcxBEUuW2Kdg/9zK8w9?= =?us-ascii?Q?m1zNPX/pf7DAydAAitXT9xgaiOEni/7cRl12+xirr3xeiuBCm/mJXeSebbY1?= =?us-ascii?Q?Dk5YWq2S6ZQMpLNx2mZ0BkX9fuBhBQ8NW3iXqmoi5mUMRTSmGpDm4O6YjkOb?= =?us-ascii?Q?X2bECb+b5BYjZQFX09La5tuoTkUVEFjt2ESSFDcDrSyw0eMjKCIjvrfk8NjK?= =?us-ascii?Q?2B8a3zmP42LwpEDgefjn6ua7o+49vRXqQEEZk3alK+WskVofpg1ldcKqw+5i?= =?us-ascii?Q?pR7jMwNm+y+pxUOxUSshESmUJA7z/b10NOXn3V/90sIaGfM3m+/LD8NA9zmv?= =?us-ascii?Q?65K6H9rRCxgHncEaWy+iO4o5dXjerak8vB+xWIOgX/Vb3yq+u+TeeyVL4fE6?= =?us-ascii?Q?ezzlKwUdXA8G2D6u9gZaHhl4fwPlShaAhjwP8kbb0GGZLgNMyxI18EL41sSx?= =?us-ascii?Q?6S6effuBN0fX2cy76raaFxZ3cgD8F43SXsBcl8z6HwmSqkSg?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 876ab29e-f9cb-4a48-6250-08de810f8477 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Mar 2026 14:47:58.1641 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: +LL6O8EXyglEgTH4z16lyZ43+XMmhxd/M2bseiuYSIPBh3jTQGbvYxcwiVX1xhse X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5778 X-Rspam-User: X-Stat-Signature: 9jth7qc53m13hfheezdu5emdkromygkr X-Rspamd-Queue-Id: 6DFA2140007 X-Rspamd-Server: rspam03 X-HE-Tag: 1773413286-959228 X-HE-Meta: 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 UdUnQ+8Z 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The added folio_split_race_test is a modified C port of the race condition test from [1]. The test creates shmem huge pages shared by both a parent and a child processes, where the parent process punches holes in the shmem to cause folio_split() in the kernel and the child process reads the shmem in 16 threads to cause filemap_get_entry() in the kernel. filemap_get_entry() reads the folio and xarray split by folio_split() locklessly. The original test[2] is written in rust and uses memfd (shmem backed). This C port uses shmem directly. Note: the initial rust to C conversion is done by Cursor. Link: https://lore.kernel.org/all/CAKNNEtw5_kZomhkugedKMPOG-sxs5Q5OLumWJdiWXv+C9Yct0w@mail.gmail.com/ [1] Link: https://github.com/dfinity/thp-madv-remove-test [2] Signed-off-by: Zi Yan Cc: Bas van Dijk Cc: Adam Bratschi-Kaye --- tools/testing/selftests/mm/Makefile | 1 + .../selftests/mm/folio_split_race_test.c | 380 ++++++++++++++++++ tools/testing/selftests/mm/run_vmtests.sh | 2 + 3 files changed, 383 insertions(+) create mode 100644 tools/testing/selftests/mm/folio_split_race_test.c diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index 90fcca53a561b..3316d8a3b7e82 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -105,6 +105,7 @@ TEST_GEN_FILES += droppable TEST_GEN_FILES += guard-regions TEST_GEN_FILES += merge TEST_GEN_FILES += rmap +TEST_GEN_FILES += folio_split_race_test ifneq ($(ARCH),arm64) TEST_GEN_FILES += soft-dirty diff --git a/tools/testing/selftests/mm/folio_split_race_test.c b/tools/testing/selftests/mm/folio_split_race_test.c new file mode 100644 index 0000000000000..cf5a5666bab77 --- /dev/null +++ b/tools/testing/selftests/mm/folio_split_race_test.c @@ -0,0 +1,380 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * The parent process creates a shmem and forks. The child creates a THP on the + * mapping, fills all pages with known patterns, and then continuously verifies + * non-punched pages. The parent punches holes via MADV_REMOVE on the shmem + * while the child reads. + * + * It tests the race condition between folio_split() and filemap_get_entry(), + * where the hole punches on shmem lead to folio_split() and reading the shmem + * lead to filemap_get_entry(). + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "vm_util.h" +#include "kselftest.h" +#include "thp_settings.h" + +uint64_t page_size; +uint64_t pmd_pagesize; +#define NR_PMD_PAGE 5 +#define FILE_SIZE (pmd_pagesize * NR_PMD_PAGE) +#define TOTAL_PAGES (FILE_SIZE / page_size) + +/* Every N-th to N+M-th pages are punched; not aligned with huge page boundaries. */ +#define PUNCH_INTERVAL 50 /* N */ +#define PUNCH_SIZE_FACTOR 3 /* M */ + +#define NUM_READER_THREADS 16 +#define FILL_BYTE 0xAF +#define NUM_ITERATIONS 100 + +#define CHILD_READY 1 +#define CHILD_FAILED 2 +/* Shared control block: MAP_SHARED anonymous so parent and child see same values. */ +struct SharedCtl { + atomic_uint_fast32_t ready; + atomic_uint_fast32_t stop; + atomic_size_t child_failures; + atomic_size_t child_verified; +}; + +static int get_errno(void) +{ + return errno; +} + +static void fill_page(unsigned char *base, size_t page_idx) +{ + unsigned char *page_ptr = base + page_idx * page_size; + uint64_t idx = (uint64_t)page_idx; + + memset(page_ptr, FILL_BYTE, page_size); + memcpy(page_ptr, &idx, sizeof(idx)); +} + +/* Returns true if valid, false if corrupted. */ +static bool check_page(unsigned char *base, size_t page_idx) +{ + unsigned char *page_ptr = base + page_idx * page_size; + uint64_t expected_idx = (uint64_t)page_idx; + uint64_t got_idx; + + memcpy(&got_idx, page_ptr, 8); + + if (got_idx != expected_idx) { + size_t off; + int all_zero = 1; + + for (off = 0; off < page_size; off++) { + if (page_ptr[off] != 0) { + all_zero = 0; + break; + } + } + if (all_zero) { + ksft_print_msg( + "CORRUPTED: page %zu (huge page %zu) is ALL ZEROS\n", + page_idx, + (page_idx * page_size) / pmd_pagesize); + } else { + ksft_print_msg( + "CORRUPTED: page %zu (huge page %zu): expected idx %zu, got %lu\n", + page_idx, (page_idx * page_size) / pmd_pagesize, + page_idx, (unsigned long)got_idx); + } + return false; + } + return true; +} + +struct reader_arg { + unsigned char *base; + struct SharedCtl *ctl; + int tid; + atomic_size_t *failures; + atomic_size_t *verified; +}; + +static void *reader_thread(void *arg) +{ + struct reader_arg *ra = (struct reader_arg *)arg; + unsigned char *base = ra->base; + struct SharedCtl *ctl = ra->ctl; + int tid = ra->tid; + atomic_size_t *failures = ra->failures; + atomic_size_t *verified = ra->verified; + size_t page_idx; + + while (atomic_load_explicit(&ctl->stop, memory_order_acquire) == 0) { + for (page_idx = (size_t)tid; page_idx < TOTAL_PAGES; + page_idx += NUM_READER_THREADS) { + if (page_idx % PUNCH_INTERVAL >= 0 && + page_idx % PUNCH_INTERVAL < PUNCH_SIZE_FACTOR) + continue; + if (check_page(base, page_idx)) + atomic_fetch_add_explicit(verified, 1, + memory_order_relaxed); + else + atomic_fetch_add_explicit(failures, 1, + memory_order_relaxed); + } + if (atomic_load_explicit(failures, memory_order_relaxed) > 0) + break; + } + + return NULL; +} + +static void child_reader_loop(unsigned char *base, struct SharedCtl *ctl) +{ + pthread_t threads[NUM_READER_THREADS]; + struct reader_arg args[NUM_READER_THREADS]; + atomic_size_t failures = 0; + atomic_size_t verified = 0; + size_t page_idx; + size_t recheck = 0; + int i; + + for (i = 0; i < NUM_READER_THREADS; i++) { + args[i].base = base; + args[i].ctl = ctl; + args[i].tid = i; + args[i].failures = &failures; + args[i].verified = &verified; + if (pthread_create(&threads[i], NULL, reader_thread, + &args[i]) != 0) + ksft_exit_fail_msg("pthread_create failed\n"); + } + + for (i = 0; i < NUM_READER_THREADS; i++) + pthread_join(threads[i], NULL); + + /* Post-sleep recheck */ + usleep(1000); /* 1 ms */ + + for (page_idx = 0; page_idx < TOTAL_PAGES; page_idx++) { + if (page_idx % PUNCH_INTERVAL >= 0 && + page_idx % PUNCH_INTERVAL < PUNCH_SIZE_FACTOR) + continue; + if (!check_page(base, page_idx)) + recheck++; + } + if (recheck) + ksft_print_msg("post-sleep failures: %zu\n", recheck); + + atomic_store_explicit(&ctl->child_failures, + atomic_load_explicit(&failures, + memory_order_relaxed), + memory_order_release); + atomic_store_explicit(&ctl->child_verified, + atomic_load_explicit(&verified, + memory_order_relaxed), + memory_order_release); +} + +/* Returns number of corrupted pages. */ +static size_t verify_pages(unsigned char *base, const bool *is_punched) +{ + size_t failures = 0; + size_t page_idx; + size_t non_punched = 0; + + for (page_idx = 0; page_idx < TOTAL_PAGES; page_idx++) { + if (is_punched[page_idx]) + continue; + if (!check_page(base, page_idx)) { + failures++; + if (failures >= 100) + return failures; + } + non_punched++; + } + if (failures) + ksft_print_msg(" %zu non-punched pages are corrupted!\n", + failures); + return failures; +} + +/* Run a single iteration. Returns total number of corrupted pages. */ +static size_t run_iteration(void) +{ + struct SharedCtl *ctl; + pid_t pid; + unsigned char *parent_base; + bool *is_punched; + size_t i; + size_t child_failures, child_verified, parent_failures; + int status; + size_t n_punched = 0; + + ctl = (struct SharedCtl *)mmap(NULL, sizeof(struct SharedCtl), PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, -1, 0); + if (ctl == MAP_FAILED) + ksft_exit_fail_msg("mmap ctl failed: %d\n", get_errno()); + + memset(ctl, 0, sizeof(struct SharedCtl)); + + parent_base = mmap(NULL, FILE_SIZE, PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, -1, 0); + + if (parent_base == MAP_FAILED) + ksft_exit_fail_msg("mmap failed: %d\n", get_errno()); + + pid = fork(); + if (pid < 0) + ksft_exit_fail_msg("fork failed: %d\n", get_errno()); + + if (pid == 0) { + /* ---- Child process ---- */ + unsigned char *child_base = parent_base; + + if (madvise(child_base, FILE_SIZE, MADV_HUGEPAGE) != 0) + ksft_exit_fail_msg("madvise(MADV_HUGEPAGE) failed: %d\n", + get_errno()); + + for (i = 0; i < TOTAL_PAGES; i++) + fill_page(child_base, i); + + if (!check_huge_shmem(child_base, NR_PMD_PAGE, pmd_pagesize)) { + atomic_store_explicit(&ctl->ready, CHILD_FAILED, memory_order_release); + ksft_print_msg("No shmem THP is allocated\n"); + _exit(0); + } + + atomic_store_explicit(&ctl->ready, CHILD_READY, memory_order_release); + child_reader_loop(child_base, ctl); + + munmap(child_base, FILE_SIZE); + _exit(0); + } + + /* ---- Parent process ---- */ + while (atomic_load_explicit(&ctl->ready, memory_order_acquire) == 0) + usleep(1000); + + if (ctl->ready == CHILD_FAILED) + ksft_exit_fail_msg("Child process error\n"); + + is_punched = calloc(TOTAL_PAGES, sizeof(bool)); + if (!is_punched) + ksft_exit_fail_msg("calloc is_punched failed\n"); + + for (i = 0; i < TOTAL_PAGES; i++) { + int j; + + if (i % PUNCH_INTERVAL != 0) + continue; + if (madvise(parent_base + i * page_size, + PUNCH_SIZE_FACTOR * page_size, MADV_REMOVE) != 0) { + ksft_exit_fail_msg( + "madvise(MADV_REMOVE) failed on page %zu: %d\n", + i, get_errno()); + } + for (j = 0; j < PUNCH_SIZE_FACTOR && i + j < TOTAL_PAGES; j++) + is_punched[i + j] = true; + + i += PUNCH_SIZE_FACTOR; + + n_punched += PUNCH_SIZE_FACTOR; + } + + atomic_store_explicit(&ctl->stop, 1, memory_order_release); + + if (waitpid(pid, &status, 0) != pid) + ksft_exit_fail_msg("waitpid failed\n"); + + child_failures = atomic_load_explicit(&ctl->child_failures, + memory_order_acquire); + child_verified = atomic_load_explicit(&ctl->child_verified, + memory_order_acquire); + if (child_failures) + ksft_print_msg("Child: %zu pages verified, %zu failures\n", + child_verified, child_failures); + + parent_failures = verify_pages(parent_base, is_punched); + if (parent_failures) + ksft_print_msg("Parent verification failures: %zu\n", + parent_failures); + + munmap(parent_base, FILE_SIZE); + munmap(ctl, sizeof(struct SharedCtl)); + free(is_punched); + + (void)n_punched; + return child_failures + parent_failures; +} + +int main(void) +{ + size_t iter; + size_t failures; + struct thp_settings current_settings; + bool failed = false; + + ksft_print_header(); + + if (!thp_is_enabled()) + ksft_exit_skip("Transparent Hugepages not available\n"); + + if (geteuid() != 0) { + ksft_print_msg("Please run the benchmark as root\n"); + ksft_finished(); + } + + thp_save_settings(); + thp_read_settings(¤t_settings); + current_settings.shmem_enabled = SHMEM_ADVISE; + thp_write_settings(¤t_settings); + + ksft_set_plan(1); + + page_size = getpagesize(); + pmd_pagesize = read_pmd_pagesize(); + + ksft_print_msg("folio split race test\n"); + ksft_print_msg("=======================================================\n"); + ksft_print_msg("Shmem size: %zu MiB\n", FILE_SIZE / 1024 / 1024); + ksft_print_msg("Total pages: %zu\n", TOTAL_PAGES); + ksft_print_msg("Child readers: %d\n", NUM_READER_THREADS); + ksft_print_msg("Punching every %dth to %dth page\n", PUNCH_INTERVAL, + PUNCH_INTERVAL + PUNCH_SIZE_FACTOR); + ksft_print_msg("Iterations: %d\n", NUM_ITERATIONS); + + for (iter = 1; iter <= NUM_ITERATIONS; iter++) { + failures = run_iteration(); + if (failures > 0) { + failed = true; + ksft_print_msg( + "FAILED on iteration %zu: %zu pages corrupted by cross-process MADV_REMOVE!\n", + iter, failures); + break; + } + } + + thp_restore_settings(); + + if (failed) { + ksft_test_result_fail("Test failed\n"); + ksft_exit_fail(); + } else { + ksft_test_result_pass("All %d iterations passed\n", NUM_ITERATIONS); + ksft_exit_pass(); + } + + return 0; +} diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh index a0b4d8a52980b..f54ec9d0edb8b 100755 --- a/tools/testing/selftests/mm/run_vmtests.sh +++ b/tools/testing/selftests/mm/run_vmtests.sh @@ -555,6 +555,8 @@ if [ -n "${MOUNTED_XFS}" ]; then rm -f ${XFS_IMG} fi +CATEGORY="thp" run_test ./folio_split_race_test + CATEGORY="migration" run_test ./migration CATEGORY="mkdirty" run_test ./mkdirty -- 2.51.0