From nobody Mon Apr 27 02:08:02 2026 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 C8FDAC43334 for ; Sat, 18 Jun 2022 07:32:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234610AbiFRHcp (ORCPT ); Sat, 18 Jun 2022 03:32:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229799AbiFRHco (ORCPT ); Sat, 18 Jun 2022 03:32:44 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2314726F6 for ; Sat, 18 Jun 2022 00:32:42 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4LQ6zS6cS0zjYj3; Sat, 18 Jun 2022 15:31:32 +0800 (CST) Received: from huawei.com (10.175.124.27) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 18 Jun 2022 15:32:40 +0800 From: Miaohe Lin To: CC: , , Subject: [PATCH] mm: stricter check on THP migration entry Date: Sat, 18 Jun 2022 15:32:43 +0800 Message-ID: <20220618073243.9423-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When VM_BUG_ON check for THP migration entry, the existing code only check thp_migration_supported case, but not for !thp_migration_supported case. If !thp_migration_supported() and !pmd_present(), the original code may dead loop in theory. To make the VM_BUG_ON check more consistent, we need to catch both cases. Signed-off-by: Miaohe Lin --- mm/memory.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index fee2884481f2..6a9a17c7f58a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5043,10 +5043,9 @@ static vm_fault_t __handle_mm_fault(struct vm_area_s= truct *vma, =20 barrier(); if (unlikely(is_swap_pmd(vmf.orig_pmd))) { - VM_BUG_ON(thp_migration_supported() && - !is_pmd_migration_entry(vmf.orig_pmd)); - if (is_pmd_migration_entry(vmf.orig_pmd)) - pmd_migration_entry_wait(mm, vmf.pmd); + VM_BUG_ON(!thp_migration_supported() || + !is_pmd_migration_entry(vmf.orig_pmd)); + pmd_migration_entry_wait(mm, vmf.pmd); return 0; } if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) { --=20 2.23.0