From patchwork Mon Jul 4 01:33:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naoya Horiguchi X-Patchwork-Id: 12904548 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 8F91BC433EF for ; Mon, 4 Jul 2022 01:33:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 317ED8E0001; Sun, 3 Jul 2022 21:33:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2A0FD6B0078; Sun, 3 Jul 2022 21:33:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 18FEF8E0001; Sun, 3 Jul 2022 21:33:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 098476B0075 for ; Sun, 3 Jul 2022 21:33:39 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id D3F73DD1 for ; Mon, 4 Jul 2022 01:33:38 +0000 (UTC) X-FDA: 79647695316.06.0D4BD55 Received: from out0.migadu.com (out0.migadu.com [94.23.1.103]) by imf28.hostedemail.com (Postfix) with ESMTP id 42A47C004D for ; Mon, 4 Jul 2022 01:33:38 +0000 (UTC) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1656898417; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=F1I02BcWpIjgDvFk+4MlrVlp1TpbgaySUNPdkhFmIaM=; b=A+nOPsGxoBTDr95l5v5rnDzy8nPqcFEjSJsAQUxmeWQN1u/oKq/1uBzEAubMOjoLLZFph8 b1CMBITvKzQTmQ1+ORt6FxEO2yLd/p2XbNWv+lvmbCrc59dkih2S+ABJYFnik0iovj1nVQ M1QoSLF1VIO3oRbiDXSaJoCF7AvZyeg= From: Naoya Horiguchi To: linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Mike Kravetz , Miaohe Lin , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , Naoya Horiguchi , linux-kernel@vger.kernel.org Subject: [mm-unstable PATCH v4 3/9] mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry Date: Mon, 4 Jul 2022 10:33:06 +0900 Message-Id: <20220704013312.2415700-4-naoya.horiguchi@linux.dev> In-Reply-To: <20220704013312.2415700-1-naoya.horiguchi@linux.dev> References: <20220704013312.2415700-1-naoya.horiguchi@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656898418; a=rsa-sha256; cv=none; b=eZMvW0FEUEbIXP0vP18wn62E7mo/U0QNQ96YqMuHyXbfpt+uo2ZjQm3BMOXnvZISCPs1Hv 8dNbRlnfGmTss27IrMK5gSCP7Jb8OnxA8Hz3Ip1PTb3GyDWJMQJsxH6fDmPPNxzuaRia+b SXXUU6APn/eT4Kh/5o3Eh1aUF90Vr9s= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=A+nOPsGx; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf28.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656898418; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=F1I02BcWpIjgDvFk+4MlrVlp1TpbgaySUNPdkhFmIaM=; b=uGvL5fJe+a6K/Zp7xAXNru0tSh0/MKs8JBPWFysFMr8JTpVxvPwkSPEuOoO8ywGb7MeXpZ 35k9E9x/WQrLKkcfj01hykRdZs65AdkyXonWbBAZgX1FB5+eO9YAY7OuBEB5t5WYWQKUsP +dBZBiIaqBkIpIuFoJ6cUC7smjo0W9I= X-Rspam-User: X-Rspamd-Server: rspam07 Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=A+nOPsGx; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf28.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev X-Stat-Signature: 7ek9xzo7zbcyt6wfepedh75am6yihhir X-Rspamd-Queue-Id: 42A47C004D X-HE-Tag: 1656898418-552073 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: 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 Reviewed-by: Miaohe Lin Reviewed-by: Mike Kravetz --- 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; } #ifdef CONFIG_HUGETLB_PAGE diff --git a/mm/hugetlb.c b/mm/hugetlb.c index ad621688370b..66bb39e0fce8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6994,10 +6994,38 @@ struct page * __weak follow_huge_pud(struct mm_struct *mm, unsigned long address, pud_t *pud, int flags) { - if (flags & (FOLL_GET | FOLL_PIN)) + struct page *page = NULL; + spinlock_t *ptl; + pte_t pte; + + if (WARN_ON_ONCE(flags & FOLL_PIN)) return NULL; - return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT); +retry: + ptl = huge_pte_lock(hstate_sizelog(PUD_SHIFT), mm, (pte_t *)pud); + if (!pud_huge(*pud)) + goto out; + pte = huge_ptep_get((pte_t *)pud); + if (pte_present(pte)) { + page = pud_page(*pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT); + if (WARN_ON_ONCE(!try_grab_page(page, flags))) { + page = NULL; + goto out; + } + } else { + if (is_hugetlb_entry_migration(pte)) { + spin_unlock(ptl); + __migration_entry_wait(mm, (pte_t *)pud, ptl); + goto retry; + } + /* + * hwpoisoned entry is treated as no_page_table in + * follow_page_mask(). + */ + } +out: + spin_unlock(ptl); + return page; } struct page * __weak