From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f197.google.com (mail-pg1-f197.google.com [209.85.215.197]) by kanga.kvack.org (Postfix) with ESMTP id 33CD08E0008 for ; Tue, 11 Sep 2018 16:58:46 -0400 (EDT) Received: by mail-pg1-f197.google.com with SMTP id g9-v6so12895209pgc.16 for ; Tue, 11 Sep 2018 13:58:46 -0700 (PDT) Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com. [115.124.30.131]) by mx.google.com with ESMTPS id e21-v6si20832405pgb.131.2018.09.11.13.58.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Sep 2018 13:58:44 -0700 (PDT) From: Yang Shi Subject: [RFC v9 PATCH 4/4] mm: unmap VM_PFNMAP mappings with optimized path Date: Wed, 12 Sep 2018 04:58:13 +0800 Message-Id: <1536699493-69195-5-git-send-email-yang.shi@linux.alibaba.com> In-Reply-To: <1536699493-69195-1-git-send-email-yang.shi@linux.alibaba.com> References: <1536699493-69195-1-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, akpm@linux-foundation.org, dave.hansen@intel.com, oleg@redhat.com, srikar@linux.vnet.ibm.com Cc: 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 | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 086f8b5..0b6b231 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2778,7 +2778,7 @@ static int do_munmap_zap_rlock(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf) { unsigned long end; - struct vm_area_struct *start_vma, *prev, *vma; + struct vm_area_struct *start_vma, *prev; int ret = 0; if (!addr_ok(start, len)) @@ -2811,16 +2811,6 @@ static int do_munmap_zap_rlock(struct mm_struct *mm, unsigned long start, goto out; } - /* - * Unmapping vmas, which have VM_PFNMAP - * need get done with write mmap_sem held since they may update - * vm_flags. Deal with such mappings with regular do_munmap() call. - */ - for (vma = start_vma; vma && vma->vm_start < end; vma = vma->vm_next) { - if (vma->vm_flags & VM_PFNMAP) - goto regular_path; - } - /* Handle mlocked vmas */ if (mm->locked_vm) munlock_vmas(start_vma, end); @@ -2844,9 +2834,6 @@ static int do_munmap_zap_rlock(struct mm_struct *mm, unsigned long start, return 0; -regular_path: - ret = do_munmap(mm, start, len, uf); - out: up_write(&mm->mmap_sem); return ret; -- 1.8.3.1