From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx177.postini.com [74.125.245.177]) by kanga.kvack.org (Postfix) with SMTP id 0F2396B0070 for ; Fri, 3 Aug 2012 10:37:54 -0400 (EDT) Date: Fri, 3 Aug 2012 16:37:48 +0200 From: Michal Hocko Subject: Re: [PATCH -mm] mm: hugetlbfs: Correctly populate shared pmd Message-ID: <20120803143748.GD8434@dhcp22.suse.cz> References: <20120802141656.GB18084@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Hillf Danton Cc: Andrew Morton , Mel Gorman , Rik van Riel , Hugh Dickins , Linux-MM , David Gibson , Ken Chen , Cong Wang On Fri 03-08-12 22:16:52, Hillf Danton wrote: > On Thu, Aug 2, 2012 at 10:16 PM, Michal Hocko wrote: > > This patch addresses the issue by moving pmd_alloc into huge_pmd_share > > which guarantees that the shared pud is populated in the same > > critical section as pmd. > > Is i_mmap_mutex for guarding new pmd allocation? It doesn't guard the pmd allocation itself it just makes sure that pud population and pmd_allocation are done atomicaly wrt. other processes to share the same pmd because sharing is synchronized by i_mmap_mutex. > Is regression introduced if sharing is unavailable? No. The bug is about the sharing as the changelog describes. -- Michal Hocko SUSE Labs -- 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