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 1A40FC433ED for ; Tue, 20 Apr 2021 13:31:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9AF266113C for ; Tue, 20 Apr 2021 13:31:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9AF266113C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 21E706B0071; Tue, 20 Apr 2021 09:31:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1CDCC6B0073; Tue, 20 Apr 2021 09:31:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0E4D16B0072; Tue, 20 Apr 2021 09:31:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0198.hostedemail.com [216.40.44.198]) by kanga.kvack.org (Postfix) with ESMTP id A6DC86B006C for ; Tue, 20 Apr 2021 09:31:49 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 6360F3653 for ; Tue, 20 Apr 2021 13:31:49 +0000 (UTC) X-FDA: 78052833138.09.BE29E06 Received: from szxga07-in.huawei.com (szxga07-in.huawei.com [45.249.212.35]) by imf12.hostedemail.com (Postfix) with ESMTP id E8A6DF2 for ; Tue, 20 Apr 2021 13:31:40 +0000 (UTC) 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-Type: text/plain X-Originating-IP: [10.175.104.175] X-CFilter-Loop: Reflected X-Stat-Signature: 7pyqifgs8skxs1dx69ts83bbrxd9cur4 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E8A6DF2 Received-SPF: none (huawei.com>: No applicable sender policy available) receiver=imf12; identity=mailfrom; envelope-from=""; helo=szxga07-in.huawei.com; client-ip=45.249.212.35 X-HE-DKIM-Result: none/none X-HE-Tag: 1618925500-428067 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 sw= ap readahead"). But this makes the code confusing. The non_swap_entry() chec= k looks racy because while we released the pte lock, somebody else might ha= ve 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_ent= ry isn't used in this function and we will have enough checking when we real= ly 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 =3D 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, =20 faddr =3D vmf->address; orig_pte =3D pte =3D pte_offset_map(vmf->pmd, faddr); - entry =3D pte_to_swp_entry(*pte); - if ((unlikely(non_swap_entry(entry)))) { - pte_unmap(orig_pte); - return; - } =20 fpfn =3D PFN_DOWN(faddr); ra_val =3D GET_SWAP_RA_VAL(vma); --=20 2.19.1