From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx128.postini.com [74.125.245.128]) by kanga.kvack.org (Postfix) with SMTP id 66A2B6B005C for ; Wed, 13 Jun 2012 23:11:40 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 700533EE0C8 for ; Thu, 14 Jun 2012 12:11:38 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 50A4145DD74 for ; Thu, 14 Jun 2012 12:11:38 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 1F2F245DE4D for ; Thu, 14 Jun 2012 12:11:38 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 0BF871DB802C for ; Thu, 14 Jun 2012 12:11:38 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.240.81.134]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id B79C21DB803F for ; Thu, 14 Jun 2012 12:11:37 +0900 (JST) Message-ID: <4FD955E8.5050100@jp.fujitsu.com> Date: Thu, 14 Jun 2012 12:09:28 +0900 From: Kamezawa Hiroyuki MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: 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 (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 -- 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