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 X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97E39C433B4 for ; Tue, 20 Apr 2021 13:31:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50769613D7 for ; Tue, 20 Apr 2021 13:31:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232131AbhDTNcT (ORCPT ); Tue, 20 Apr 2021 09:32:19 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:17803 "EHLO szxga07-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232142AbhDTNcR (ORCPT ); Tue, 20 Apr 2021 09:32:17 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4FPl021qN7zBrVB; Tue, 20 Apr 2021 21:29:22 +0800 (CST) Received: from huawei.com (10.175.104.175) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.498.0; Tue, 20 Apr 2021 21:31:39 +0800 From: Miaohe Lin To: CC: , , , , , , , , , , , , , , Subject: [PATCH v3 3/4] mm/swap: remove confusing checking for non_swap_entry() in swap_ra_info() Date: Tue, 20 Apr 2021 09:30:47 -0400 Message-ID: <20210420133048.6773-4-linmiaohe@huawei.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20210420133048.6773-1-linmiaohe@huawei.com> References: <20210420133048.6773-1-linmiaohe@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.104.175] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The non_swap_entry() was used for working with VMA based swap readahead via commit ec560175c0b6 ("mm, swap: VMA based swap readahead"). Then it's moved to swap_ra_info() since commit eaf649ebc3ac ("mm: swap: clean up swap readahead"). But this makes the code confusing. The non_swap_entry() check looks racy because while we released the pte lock, somebody else might have faulted in this pte. So we should check whether it's swap pte first to guard against such race or swap_type will be unexpected. But the swap_entry isn't used in this function and we will have enough checking when we really operate the PTE entries later. So checking for non_swap_entry() is not really needed here and should be removed to avoid confusion. Signed-off-by: Miaohe Lin --- mm/swap_state.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index 272ea2108c9d..df5405384520 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -721,7 +721,6 @@ static void swap_ra_info(struct vm_fault *vmf, { struct vm_area_struct *vma = vmf->vma; unsigned long ra_val; - swp_entry_t entry; unsigned long faddr, pfn, fpfn; unsigned long start, end; pte_t *pte, *orig_pte; @@ -739,11 +738,6 @@ static void swap_ra_info(struct vm_fault *vmf, faddr = vmf->address; orig_pte = pte = pte_offset_map(vmf->pmd, faddr); - entry = pte_to_swp_entry(*pte); - if ((unlikely(non_swap_entry(entry)))) { - pte_unmap(orig_pte); - return; - } fpfn = PFN_DOWN(faddr); ra_val = GET_SWAP_RA_VAL(vma); -- 2.19.1