From nobody Fri Dec 19 20:19:03 2025 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ABA321AB6FF for ; Wed, 22 Jan 2025 06:18:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.191 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737526738; cv=none; b=fHk/N8aOs2cBND+suCvcXhXrM5UmiZyiQ9qtC1JDg+7YqXqtdcql4OPgSxOqFr4hQdHqAMcWDZsRIIIM9vLI6vegymGcAKrPczWZxwnjZhhUwEUYOj6pePLa+D2cpiq7DgqwmcKL0BP6EKsjKNMGLbZG63Yzg99O4pi7fQJIfiQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737526738; c=relaxed/simple; bh=hVU+Fe67WTeYI+NkDUAPRWvgq8/8JGgtnsFuR7dC7vY=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=fkPHNMQKAWP9gzh/PWea2M4g51aA8N3oZsSQdXqkHY18xaJIMIfV+QjpDrWSrUFblWIhhLuuI+9xjWc2Ac2yr2xDgakFK7TbA2B0SNl7pJiLS0ttfPwQVNkbAcPRIWLjEw4oPbuBtkQ5VTU/t+FHtMLa7MkCCp8nweSIMfszKCI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.191 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.214]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4YdDQS2Vx1z1JHlY; Wed, 22 Jan 2025 14:17:52 +0800 (CST) Received: from kwepemg200013.china.huawei.com (unknown [7.202.181.64]) by mail.maildlp.com (Postfix) with ESMTPS id 8CF7E1A016C; Wed, 22 Jan 2025 14:18:52 +0800 (CST) Received: from huawei.com (10.175.113.32) by kwepemg200013.china.huawei.com (7.202.181.64) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 22 Jan 2025 14:18:51 +0800 From: Liu Shixin To: Andrew Morton , Kefeng Wang , Muchun Song , David Hildenbrand , Zi Yan , Johannes Weiner , "Kirill A . Shutemov" , Nanyong Sun CC: , , Liu Shixin Subject: [PATCH] mm: page_isolation: avoid call folio_hstate() without hugetlb_lock Date: Wed, 22 Jan 2025 14:11:51 +0800 Message-ID: <20250122061151.578768-1-liushixin2@huawei.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemg200013.china.huawei.com (7.202.181.64) Content-Type: text/plain; charset="utf-8" I found a NULL pointer dereference as followed: BUG: kernel NULL pointer dereference, address: 0000000000000028 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP PTI CPU: 5 UID: 0 PID: 5964 Comm: sh Kdump: loaded Not tainted 6.13.0-dirty #20 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu= 1. RIP: 0010:has_unmovable_pages+0x184/0x360 ... Call Trace: set_migratetype_isolate+0xd1/0x180 start_isolate_page_range+0xd2/0x170 alloc_contig_range_noprof+0x101/0x660 alloc_contig_pages_noprof+0x238/0x290 alloc_gigantic_folio.isra.0+0xb6/0x1f0 only_alloc_fresh_hugetlb_folio.isra.0+0xf/0x60 alloc_pool_huge_folio+0x80/0xf0 set_max_huge_pages+0x211/0x490 __nr_hugepages_store_common+0x5f/0xe0 nr_hugepages_store+0x77/0x80 kernfs_fop_write_iter+0x118/0x200 vfs_write+0x23c/0x3f0 ksys_write+0x62/0xe0 do_syscall_64+0x5b/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e As has_unmovable_pages() call folio_hstate() without hugetlb_lock, there is a race to free the HugeTLB page between PageHuge() and folio_hstate(). There is no need to add hugetlb_lock here as the HugeTLB page can be freed in lot of places. So it's enough to unfold folio_hstate() and add a check to avoid NULL pointer dereference for hugepage_migration_supported(). Fixes: 464c7ffbcb16 ("mm/hugetlb: filter out hugetlb pages if HUGEPAGE migr= ation is not supported.") Signed-off-by: Liu Shixin Acked-by: David Hildenbrand Acked-by: Zi Yan Reviewed-by: Oscar Salvador --- mm/page_isolation.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 7e04047977cf..2a38f429defb 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -83,7 +83,14 @@ static struct page *has_unmovable_pages(unsigned long st= art_pfn, unsigned long e unsigned int skip_pages; =20 if (PageHuge(page)) { - if (!hugepage_migration_supported(folio_hstate(folio))) + struct hstate *h; + + /* + * The huge page may be freed so can not + * use folio_hstate() directly. + */ + h =3D size_to_hstate(folio_size(folio)); + if (h && !hugepage_migration_supported(h)) return page; } else if (!folio_test_lru(folio) && !__folio_test_movable(folio)) { return page; --=20 2.34.1