From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8C85963B8 for ; Mon, 20 Feb 2023 13:47:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C7A9AC433D2; Mon, 20 Feb 2023 13:47:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1676900848; bh=9In/DZN978t1MAQ5alfdS1aVD9vZaZYZUUfq0Me2QTg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K5xqTTYgGFuvpC+bNl/BTEfxZpuDynsKgRG1o0A/cTTtLXZoKuzJt+B7cXFfa/zhg 9tCDCuobOPTovxGuMMJ7nrOW3xJ3apiNQoU0QOrJYTTu59+FzPFvtddbCYh2F+jeJx 2/FShDS1YRH1hSDTXofE4Sv2l6EjqNXdles6+T4A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mike Kravetz , Peter Xu , David Hildenbrand , James Houghton , Matthew Wilcox , Michal Hocko , Muchun Song , Naoya Horiguchi , "Vishal Moola (Oracle)" , Yang Shi , Andrew Morton Subject: [PATCH 5.4 090/156] migrate: hugetlb: check for hugetlb shared PMD in node migration Date: Mon, 20 Feb 2023 14:35:34 +0100 Message-Id: <20230220133606.190601278@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230220133602.515342638@linuxfoundation.org> References: <20230220133602.515342638@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Mike Kravetz commit 73bdf65ea74857d7fb2ec3067a3cec0e261b1462 upstream. migrate_pages/mempolicy semantics state that CAP_SYS_NICE is required to move pages shared with another process to a different node. page_mapcount > 1 is being used to determine if a hugetlb page is shared. However, a hugetlb page will have a mapcount of 1 if mapped by multiple processes via a shared PMD. As a result, hugetlb pages shared by multiple processes and mapped with a shared PMD can be moved by a process without CAP_SYS_NICE. To fix, check for a shared PMD if mapcount is 1. If a shared PMD is found consider the page shared. Link: https://lkml.kernel.org/r/20230126222721.222195-3-mike.kravetz@oracle.com Fixes: e2d8cf405525 ("migrate: add hugepage migration code to migrate_pages()") Signed-off-by: Mike Kravetz Acked-by: Peter Xu Acked-by: David Hildenbrand Cc: James Houghton Cc: Matthew Wilcox Cc: Michal Hocko Cc: Muchun Song Cc: Naoya Horiguchi Cc: Vishal Moola (Oracle) Cc: Yang Shi Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/mempolicy.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -571,7 +571,8 @@ static int queue_pages_hugetlb(pte_t *pt goto unlock; /* With MPOL_MF_MOVE, we migrate only unshared hugepage. */ if (flags & (MPOL_MF_MOVE_ALL) || - (flags & MPOL_MF_MOVE && page_mapcount(page) == 1)) + (flags & MPOL_MF_MOVE && page_mapcount(page) == 1 && + !hugetlb_pmd_shared(pte))) isolate_huge_page(page, qp->pagelist); unlock: spin_unlock(ptl);