From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f198.google.com (mail-pl1-f198.google.com [209.85.214.198]) by kanga.kvack.org (Postfix) with ESMTP id C695B8E0003 for ; Fri, 14 Sep 2018 16:35:32 -0400 (EDT) Received: by mail-pl1-f198.google.com with SMTP id b6-v6so4831769pls.16 for ; Fri, 14 Sep 2018 13:35:32 -0700 (PDT) Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com. [115.124.30.133]) by mx.google.com with ESMTPS id y5-v6si6912247pll.89.2018.09.14.13.35.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Sep 2018 13:35:31 -0700 (PDT) From: Yang Shi Subject: [RFC v10 PATCH 3/3] mm: unmap VM_PFNMAP mappings with optimized path Date: Sat, 15 Sep 2018 04:34:59 +0800 Message-Id: <1536957299-43536-4-git-send-email-yang.shi@linux.alibaba.com> In-Reply-To: <1536957299-43536-1-git-send-email-yang.shi@linux.alibaba.com> References: <1536957299-43536-1-git-send-email-yang.shi@linux.alibaba.com> Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org, willy@infradead.org, ldufour@linux.vnet.ibm.com, vbabka@suse.cz, kirill@shutemov.name, akpm@linux-foundation.org Cc: dave.hansen@intel.com, oleg@redhat.com, srikar@linux.vnet.ibm.com, yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org When unmapping VM_PFNMAP mappings, vm flags need to be updated. Since the vmas have been detached, so it sounds safe to update vm flags with read mmap_sem. Cc: Michal Hocko Cc: Vlastimil Babka Signed-off-by: Yang Shi --- mm/mmap.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 991e066..04c1d3b 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2771,15 +2771,6 @@ static int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len, munlock_vma_pages_all(tmp); } - /* - * Unmapping vmas, which have VM_HUGETLB or VM_PFNMAP, - * need get done with write mmap_sem held since they may - * update vm_flags. - */ - if (downgrade && - (tmp->vm_flags & VM_PFNMAP)) - downgrade = false; - tmp = tmp->vm_next; } } -- 1.8.3.1