From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754524AbcLTWX5 (ORCPT ); Tue, 20 Dec 2016 17:23:57 -0500 Received: from mga09.intel.com ([134.134.136.24]:15595 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753055AbcLTWXv (ORCPT ); Tue, 20 Dec 2016 17:23:51 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,380,1477983600"; d="scan'208";a="45107574" From: Ross Zwisler To: linux-kernel@vger.kernel.org Cc: Ross Zwisler , Alexander Viro , Andrew Morton , Christoph Hellwig , Dan Williams , Dave Chinner , Dave Hansen , Jan Kara , Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@ml01.01.org Subject: [PATCH 1/2] mm: add follow_pte_pmd() Date: Tue, 20 Dec 2016 15:23:05 -0700 Message-Id: <1482272586-21177-2-git-send-email-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1482272586-21177-1-git-send-email-ross.zwisler@linux.intel.com> References: <1482272586-21177-1-git-send-email-ross.zwisler@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Similar to follow_pte(), follow_pte_pmd() allows either a PTE leaf or a huge page PMD leaf to be found and returned. Signed-off-by: Ross Zwisler Suggested-by: Dave Hansen --- include/linux/mm.h | 2 ++ mm/memory.c | 37 ++++++++++++++++++++++++++++++------- 2 files changed, 32 insertions(+), 7 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 4424784..ff0e1c1 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1212,6 +1212,8 @@ void unmap_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen, int even_cows); int follow_pte(struct mm_struct *mm, unsigned long address, pte_t **ptepp, spinlock_t **ptlp); +int follow_pte_pmd(struct mm_struct *mm, unsigned long address, + pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp); int follow_pfn(struct vm_area_struct *vma, unsigned long address, unsigned long *pfn); int follow_phys(struct vm_area_struct *vma, unsigned long address, diff --git a/mm/memory.c b/mm/memory.c index 455c3e6..29edd91 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3779,8 +3779,8 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) } #endif /* __PAGETABLE_PMD_FOLDED */ -static int __follow_pte(struct mm_struct *mm, unsigned long address, - pte_t **ptepp, spinlock_t **ptlp) +static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address, + pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp) { pgd_t *pgd; pud_t *pud; @@ -3797,11 +3797,20 @@ static int __follow_pte(struct mm_struct *mm, unsigned long address, pmd = pmd_offset(pud, address); VM_BUG_ON(pmd_trans_huge(*pmd)); - if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) - goto out; - /* We cannot handle huge page PFN maps. Luckily they don't exist. */ - if (pmd_huge(*pmd)) + if (pmd_huge(*pmd)) { + if (!pmdpp) + goto out; + + *ptlp = pmd_lock(mm, pmd); + if (pmd_huge(*pmd)) { + *pmdpp = pmd; + return 0; + } + spin_unlock(*ptlp); + } + + if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) goto out; ptep = pte_offset_map_lock(mm, pmd, address, ptlp); @@ -3824,9 +3833,23 @@ int follow_pte(struct mm_struct *mm, unsigned long address, pte_t **ptepp, /* (void) is needed to make gcc happy */ (void) __cond_lock(*ptlp, - !(res = __follow_pte(mm, address, ptepp, ptlp))); + !(res = __follow_pte_pmd(mm, address, ptepp, NULL, + ptlp))); + return res; +} + +int follow_pte_pmd(struct mm_struct *mm, unsigned long address, + pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp) +{ + int res; + + /* (void) is needed to make gcc happy */ + (void) __cond_lock(*ptlp, + !(res = __follow_pte_pmd(mm, address, ptepp, pmdpp, + ptlp))); return res; } +EXPORT_SYMBOL(follow_pte_pmd); /** * follow_pfn - look up PFN at a user virtual address -- 2.7.4