From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755200Ab2FNDLk (ORCPT ); Wed, 13 Jun 2012 23:11:40 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:55120 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754862Ab2FNDLj (ORCPT ); Wed, 13 Jun 2012 23:11:39 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <4FD955E8.5050100@jp.fujitsu.com> Date: Thu, 14 Jun 2012 12:09:28 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: "Aneesh Kumar K.V" CC: linux-mm@kvack.org, dhillf@gmail.com, rientjes@google.com, mhocko@suse.cz, akpm@linux-foundation.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Subject: Re: [PATCH -V9 05/15] hugetlb: avoid taking i_mmap_mutex in unmap_single_vma() for hugetlb References: <1339583254-895-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1339583254-895-6-git-send-email-aneesh.kumar@linux.vnet.ibm.com> In-Reply-To: <1339583254-895-6-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2012/06/13 19:27), Aneesh Kumar K.V wrote: > From: "Aneesh Kumar K.V" > > i_mmap_mutex lock was added in unmap_single_vma by 502717f4e ("hugetlb: > fix linked list corruption in unmap_hugepage_range()") but we don't use > page->lru in unmap_hugepage_range any more. Also the lock was taken > higher up in the stack in some code path. That would result in deadlock. > > unmap_mapping_range (i_mmap_mutex) > -> unmap_mapping_range_tree > -> unmap_mapping_range_vma > -> zap_page_range_single > -> unmap_single_vma > -> unmap_hugepage_range (i_mmap_mutex) > > For shared pagetable support for huge pages, since pagetable pages are ref > counted we don't need any lock during huge_pmd_unshare. We do take > i_mmap_mutex in huge_pmd_share while walking the vma_prio_tree in mapping. > (39dde65c9940c97f ("shared page table for hugetlb page")). > > Signed-off-by: Aneesh Kumar K.V Acked-by: KAMEZAWA Hiroyuki