From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 5A4EF6B01E3 for ; Wed, 12 May 2010 20:42:37 -0400 (EDT) Received: from m6.gw.fujitsu.co.jp ([10.0.50.76]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o4D0gWOC026393 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 13 May 2010 09:42:32 +0900 Received: from smail (m6 [127.0.0.1]) by outgoing.m6.gw.fujitsu.co.jp (Postfix) with ESMTP id 3F84145DE4E for ; Thu, 13 May 2010 09:42:32 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (s6.gw.fujitsu.co.jp [10.0.50.96]) by m6.gw.fujitsu.co.jp (Postfix) with ESMTP id 1FB6745DE52 for ; Thu, 13 May 2010 09:42:32 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id F0DB11DB8014 for ; Thu, 13 May 2010 09:42:31 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 95EBAE08001 for ; Thu, 13 May 2010 09:42:31 +0900 (JST) Date: Thu, 13 May 2010 09:38:28 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 3/5] track the root (oldest) anon_vma Message-Id: <20100513093828.1cd022db.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100512133958.3aff0515@annuminas.surriel.com> References: <20100512133815.0d048a86@annuminas.surriel.com> <20100512133958.3aff0515@annuminas.surriel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: Andrew Morton , Mel Gorman , Andrea Arcangeli , Minchan Kim , Linux-MM , LKML , Linus Torvalds List-ID: On Wed, 12 May 2010 13:39:58 -0400 Rik van Riel wrote: > Subject: track the root (oldest) anon_vma > > Track the root (oldest) anon_vma in each anon_vma tree. Because we only > take the lock on the root anon_vma, we cannot use the lock on higher-up > anon_vmas to lock anything. This makes it impossible to do an indirect > lookup of the root anon_vma, since the data structures could go away from > under us. > > However, a direct pointer is safe because the root anon_vma is always the > last one that gets freed on munmap or exit, by virtue of the same_vma list > order and unlink_anon_vmas walking the list forward. > > Signed-off-by: Rik van Riel Acked-by: KAMEZAWA Hiroyuki I welcome this. Thank you! Reading 4/5, I felt I'm grad if you add a Documentation or very-precise-comment about the new anon_vma rules and the _meaning_ of anon_vma_root_lock. I cannot fully convice myself that I understand them all. -- 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