From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id E77C828026B for ; Thu, 15 Sep 2016 07:56:37 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id v67so90235801pfv.1 for ; Thu, 15 Sep 2016 04:56:37 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id bx7si3466408pac.110.2016.09.15.04.56.37 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 15 Sep 2016 04:56:37 -0700 (PDT) From: "Kirill A. Shutemov" Subject: [PATCHv3 12/41] thp: handle write-protection faults for file THP Date: Thu, 15 Sep 2016 14:54:54 +0300 Message-Id: <20160915115523.29737-13-kirill.shutemov@linux.intel.com> In-Reply-To: <20160915115523.29737-1-kirill.shutemov@linux.intel.com> References: <20160915115523.29737-1-kirill.shutemov@linux.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Theodore Ts'o , Andreas Dilger , Jan Kara , Andrew Morton Cc: Alexander Viro , Hugh Dickins , Andrea Arcangeli , Dave Hansen , Vlastimil Babka , Matthew Wilcox , Ross Zwisler , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, "Kirill A. Shutemov" For filesystems that wants to be write-notified (has mkwrite), we will encount write-protection faults for huge PMDs in shared mappings. The easiest way to handle them is to clear the PMD and let it refault as wriable. Signed-off-by: Kirill A. Shutemov --- mm/memory.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index 83be99d9d8a1..aad8d5c6311f 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3451,8 +3451,17 @@ static int wp_huge_pmd(struct fault_env *fe, pmd_t orig_pmd) return fe->vma->vm_ops->pmd_fault(fe->vma, fe->address, fe->pmd, fe->flags); + if (fe->vma->vm_flags & VM_SHARED) { + /* Clear PMD */ + zap_page_range_single(fe->vma, fe->address, + HPAGE_PMD_SIZE, NULL); + VM_BUG_ON(!pmd_none(*fe->pmd)); + + /* Refault to establish writable PMD */ + return 0; + } + /* COW handled on pte level: split pmd */ - VM_BUG_ON_VMA(fe->vma->vm_flags & VM_SHARED, fe->vma); split_huge_pmd(fe->vma, fe->pmd, fe->address); return VM_FAULT_FALLBACK; -- 2.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org