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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F8B3C00144 for ; Mon, 1 Aug 2022 22:29:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 89BD28E0001; Mon, 1 Aug 2022 18:29:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8245D6B0072; Mon, 1 Aug 2022 18:29:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 69DFB8E0001; Mon, 1 Aug 2022 18:29:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 4CB556B0071 for ; Mon, 1 Aug 2022 18:29:21 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 18C02A0827 for ; Mon, 1 Aug 2022 22:29:21 +0000 (UTC) X-FDA: 79752466122.22.227744D Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf13.hostedemail.com (Postfix) with ESMTP id AC6A020032 for ; Mon, 1 Aug 2022 22:29:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659392960; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=nO9rzt8RTgLMwaRqiQxl7KyQRLvb8DJJM7mg9Wbz5oA=; b=MWkfHk1V/4wfMDOq8KEvf1fNtptZXw9ldL3S/lHVm2R08uu1L9dIFFAGF7HTSDRusQyCtz +NRl2HA50/g0Aymu3LA14+guCWHaxuzDDBAUmr94+ggv7nDAZkkI2WreOOFUqO3l3w1wsy kNs6kwTszYBFbFftCDVew2zN6gD+jvQ= Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-245-kdBV3BUxO1WkXDAdlEtSaw-1; Mon, 01 Aug 2022 18:29:19 -0400 X-MC-Unique: kdBV3BUxO1WkXDAdlEtSaw-1 Received: by mail-qv1-f71.google.com with SMTP id cz12-20020a056214088c00b004763e7e7d81so3225850qvb.21 for ; Mon, 01 Aug 2022 15:29:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=nO9rzt8RTgLMwaRqiQxl7KyQRLvb8DJJM7mg9Wbz5oA=; b=q/u19alvqjxnnf3pDaTlFo62vO5tscxhLAjS6EDjcBUfhyIe7iuODf20pq02dQFG2n Ei+m2atA2ZpfxsrgfuC8RA1Q5DQ0j4wA+Ri0WrVqlG84DUv1JwzUYnMYweRbLFPPxrs/ ZNvQcPNY2AhKJ8ZZd3N3nwooR4UZtz/EkHYfEo1vmU9YqjG7ZAjLZp9mYOUPMAbkvLgN TWhTrgSUhG45vnB67SF/AB8Pnd+0PLnAtE7ZNqns92WgJySrLgDre72R+As9etOoH6qc qJkFzigIL1nZJN0AYx031IIPvlqTC7FrQfsNpTOIrB4nH9bh4H57XjBMMTUIpV1j0v7R e5Cg== X-Gm-Message-State: ACgBeo0ZosAAui5C/KLIkNtN/qKo+V2gmMdDm0p7Kvyq+Yu/nTQuzJXG y/J2eCMOVte0i09IPhvOMydePNCqlKD2HGVyxa6JGWTUn97lMhVRLsRtHTpsOrzst9DyqZwb7oK ZnrMu0ZzXdXE= X-Received: by 2002:a05:6214:2409:b0:432:bf34:362f with SMTP id fv9-20020a056214240900b00432bf34362fmr16036112qvb.66.1659392958757; Mon, 01 Aug 2022 15:29:18 -0700 (PDT) X-Google-Smtp-Source: AA6agR7U7Dy41L+g9zzEtqQWOsczW+Lm3ky/InocSNKlujTF0RjMOD7NpOwKWOi3xT9bPkkckbVqMg== X-Received: by 2002:a05:6214:2409:b0:432:bf34:362f with SMTP id fv9-20020a056214240900b00432bf34362fmr16036096qvb.66.1659392958531; Mon, 01 Aug 2022 15:29:18 -0700 (PDT) Received: from xz-m1.local (bras-base-aurron9127w-grc-35-70-27-3-10.dsl.bell.ca. [70.27.3.10]) by smtp.gmail.com with ESMTPSA id bs8-20020a05620a470800b006a34a22bc60sm9424218qkb.9.2022.08.01.15.29.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Aug 2022 15:29:18 -0700 (PDT) Date: Mon, 1 Aug 2022 18:29:16 -0400 From: Peter Xu To: "Huang, Ying" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrea Arcangeli , Andrew Morton , "Kirill A . Shutemov" , Nadav Amit , Hugh Dickins , David Hildenbrand , Vlastimil Babka Subject: Re: [PATCH RFC 1/4] mm/swap: Add swp_offset_pfn() to fetch PFN from swap entry Message-ID: References: <20220729014041.21292-1-peterx@redhat.com> <20220729014041.21292-2-peterx@redhat.com> <8735eglkp5.fsf@yhuang6-desk2.ccr.corp.intel.com> MIME-Version: 1.0 In-Reply-To: <8735eglkp5.fsf@yhuang6-desk2.ccr.corp.intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659392960; a=rsa-sha256; cv=none; b=mFIU2tJQ3EWHnE7TmDj7Yc0V5Zr4RJKOQXQltDp/e8670h3/8LLrWSnvbjYEbLb1h0y7x/ VdI4MtQJfQ5CkenJk3eZNQGyTfLh9KI7suQHkusKuDhuiiqMCfDmwzKTbXwop0BKAgCPTh ntcJQBIbtVNTAvCBDSF97BMfUSpr63I= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=MWkfHk1V; spf=pass (imf13.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659392960; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=nO9rzt8RTgLMwaRqiQxl7KyQRLvb8DJJM7mg9Wbz5oA=; b=ZHL384BwOW721pHn0SlKTLc8J8Us3WK+OGxaYYXS1k6i9SZw1iOYqmuxl+yGBAY8F3opeJ hZevCZNhIxbD+zUWGDN9L2ihCJr9tKHRfGCRTm21EHAxBlPW9334fMtGsFX91xeDNC42zH bWoFdwoJ397zetV3b1VqPW16RK6ArHE= X-Stat-Signature: dc7mn6of6qhajykzj4k93bao5b4znh1n X-Rspamd-Queue-Id: AC6A020032 X-Rspam-User: Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=MWkfHk1V; spf=pass (imf13.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam03 X-HE-Tag: 1659392960-200736 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: On Mon, Aug 01, 2022 at 11:13:58AM +0800, Huang, Ying wrote: > > +/* > > + * This should only be called upon a pfn swap entry to get the PFN stored > > + * in the swap entry. Please refers to is_pfn_swap_entry() for definition > > + * of pfn swap entry. > > + */ > > +static inline unsigned long swp_offset_pfn(swp_entry_t entry) > > +{ > > Is it good to call is_pfn_swap_entry() here for debug that can be > eliminated in the production kernel? Sure, I'll add a VM_BUG_ON() there in the next spin. > > > + return swp_offset(entry) & SWP_PFN_MASK; > > +} > > + > > /* check whether a pte points to a swap entry */ > > static inline int is_swap_pte(pte_t pte) > > { > > @@ -369,7 +387,7 @@ static inline int pte_none_mostly(pte_t pte) > > > > static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry) > > { > > - struct page *p = pfn_to_page(swp_offset(entry)); > > + struct page *p = pfn_to_page(swp_offset_pfn(entry)); > > > > /* > > * Any use of migration entries may only occur while the > > @@ -387,6 +405,9 @@ static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry) > > */ > > static inline bool is_pfn_swap_entry(swp_entry_t entry) > > { > > + /* Make sure the swp offset can always store the needed fields */ > > + BUILD_BUG_ON(SWP_TYPE_SHIFT < SWP_PFN_BITS); > > BUILD_BUG_ON(SWP_TYPE_SHIFT <= SWP_PFN_BITS); Logiclaly it's okay to have SWP_TYPE_SHIFT==SWP_PFN_BITS? Thanks, -- Peter Xu