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 2919FC433EF for ; Wed, 6 Jul 2022 03:08:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A34438E0002; Tue, 5 Jul 2022 23:08:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9E34D8E0001; Tue, 5 Jul 2022 23:08:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 885268E0002; Tue, 5 Jul 2022 23:08:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 746658E0001 for ; Tue, 5 Jul 2022 23:08:02 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 47D9980B24 for ; Wed, 6 Jul 2022 03:08:02 +0000 (UTC) X-FDA: 79655190804.30.B469787 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf11.hostedemail.com (Postfix) with ESMTP id 6EB3D40002 for ; Wed, 6 Jul 2022 03:08:01 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Ld4FM0ZqVzkWKs; Wed, 6 Jul 2022 11:06:31 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) 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; Wed, 6 Jul 2022 11:07:57 +0800 Subject: Re: [mm-unstable PATCH v4 3/9] mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry To: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= CC: Naoya Horiguchi , "linux-mm@kvack.org" , Andrew Morton , David Hildenbrand , Mike Kravetz , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , "linux-kernel@vger.kernel.org" References: <20220704013312.2415700-1-naoya.horiguchi@linux.dev> <20220704013312.2415700-4-naoya.horiguchi@linux.dev> <83aff2eb-7190-7f5d-d81d-3eff0f56c40e@huawei.com> <20220705090450.GB2508809@hori.linux.bs1.fc.nec.co.jp> From: Miaohe Lin Message-ID: <531c27d3-3d12-25f1-b461-48240cf8568f@huawei.com> Date: Wed, 6 Jul 2022 11:07:57 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220705090450.GB2508809@hori.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657076881; a=rsa-sha256; cv=none; b=4pPsMJXNyMkuxcUpAEusgUgX6rfGZ5us6eL4ifnBkcNBHBieX68z+wVYuLBEh3851RG6nn aWAR8MlBp0gvDwMW58PU5glHZMn8xhlMHvDFDAaxlfaOsEr5xk8b1dTyUe+f4H+V1Ro2dE 8xpEvRhvwGnkg12/EEQPUfTteFYf+wo= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf11.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657076881; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=75yJ11ExWAzjHEUP1Qz4GRYoSZx3A4AJ2ocEbSTNlts=; b=x7NJfDvkS7ZqnHKMz1PEL5i9PAbIWyZcYoXx2kevfpRPoIoZBX9SlnpXeYTdErhJEk320S KnDiVCqMkMrFbd+AI29wFuPWQxpHcGCDF0eQoZvy0HI9jJSa3bFn8o6cz8xvGMzkGLVBdw BBqLcAnE8y4fB6Tlo5uxOwI2s5/RVKM= X-Stat-Signature: jdim5mhy474y954inowz7pdb5859g16e X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6EB3D40002 Authentication-Results: imf11.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf11.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-HE-Tag: 1657076881-601099 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 2022/7/5 17:04, HORIGUCHI NAOYA(堀口 直也) wrote: > On Tue, Jul 05, 2022 at 10:46:09AM +0800, Miaohe Lin wrote: >> On 2022/7/4 9:33, Naoya Horiguchi wrote: >>> From: Naoya Horiguchi >>> >>> follow_pud_mask() does not support non-present pud entry now. As long as >>> I tested on x86_64 server, follow_pud_mask() still simply returns >>> no_page_table() for non-present_pud_entry() due to pud_bad(), so no severe >>> user-visible effect should happen. But generally we should call >>> follow_huge_pud() for non-present pud entry for 1GB hugetlb page. >>> >>> Update pud_huge() and follow_huge_pud() to handle non-present pud entries. >>> The changes are similar to previous works for pud entries commit e66f17ff7177 >>> ("mm/hugetlb: take page table lock in follow_huge_pmd()") and commit >>> cbef8478bee5 ("mm/hugetlb: pmd_huge() returns true for non-present hugepage"). >>> >>> Signed-off-by: Naoya Horiguchi >>> --- >>> v2 -> v3: >>> - fixed typos in subject and description, >>> - added comment on pud_huge(), >>> - added comment about fallback for hwpoisoned entry, >>> - updated initial check about FOLL_{PIN,GET} flags. >>> --- >>> arch/x86/mm/hugetlbpage.c | 8 +++++++- >>> mm/hugetlb.c | 32 ++++++++++++++++++++++++++++++-- >>> 2 files changed, 37 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c >>> index 509408da0da1..6b3033845c6d 100644 >>> --- a/arch/x86/mm/hugetlbpage.c >>> +++ b/arch/x86/mm/hugetlbpage.c >>> @@ -30,9 +30,15 @@ int pmd_huge(pmd_t pmd) >>> (pmd_val(pmd) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT; >>> } >>> >>> +/* >>> + * pud_huge() returns 1 if @pud is hugetlb related entry, that is normal >>> + * hugetlb entry or non-present (migration or hwpoisoned) hugetlb entry. >>> + * Otherwise, returns 0. >>> + */ >>> int pud_huge(pud_t pud) >>> { >>> - return !!(pud_val(pud) & _PAGE_PSE); >>> + return !pud_none(pud) && >>> + (pud_val(pud) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT; >>> } >> >> Question: Is aarch64 supported too? It seems aarch64 version of pud_huge matches >> the requirement naturally for me. > > I think that if pmd_huge() and pud_huge() return true for non-present > pmd/pud entries, that's OK. Otherwise we need update to support the > new feature. > > In aarch64, the bits in pte/pmd/pud related to {pmd,pud}_present() and > {pmd,pud}_huge() seem not to overlap with the bit range for swap type > and swap offset, so maybe that's fine. But I recommend to test with > arm64 if you have access to aarch64 servers. I see. This series is intended to enable 1GB hugepage support on x86. And if someone wants to use it in other arches, it's better to have a test first. ;) Thanks. > >> >> Anyway, this patch looks good to me. >> >> Reviewed-by: Miaohe Lin > > Thank you for reviewing. > > - Naoya Horiguchi >