From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 79F458E0001 for ; Wed, 26 Sep 2018 07:14:24 -0400 (EDT) Received: by mail-ed1-f72.google.com with SMTP id v14-v6so1104956edq.10 for ; Wed, 26 Sep 2018 04:14:24 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id t22-v6si1180459edr.225.2018.09.26.04.14.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Sep 2018 04:14:23 -0700 (PDT) Subject: Re: [v11 PATCH 3/3] mm: unmap VM_PFNMAP mappings with optimized path References: <1537376621-51150-1-git-send-email-yang.shi@linux.alibaba.com> <1537376621-51150-4-git-send-email-yang.shi@linux.alibaba.com> From: Vlastimil Babka Message-ID: <889734e0-d2a9-3191-8d48-5c95bf29fb3f@suse.cz> Date: Wed, 26 Sep 2018 13:11:45 +0200 MIME-Version: 1.0 In-Reply-To: <1537376621-51150-4-git-send-email-yang.shi@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Yang Shi , mhocko@kernel.org, willy@infradead.org, ldufour@linux.vnet.ibm.com, kirill@shutemov.name, akpm@linux-foundation.org Cc: dave.hansen@intel.com, oleg@redhat.com, srikar@linux.vnet.ibm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On 9/19/18 7:03 PM, Yang Shi wrote: > 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 > Reviewed-by: Matthew Wilcox > 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 490340e..847a17d 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, Ah, the comment should have been already updated with the previous patch. But nevermind as that all goes away. Acked-by: Vlastimil Babka > - * 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; > } > } >