From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zps18.corp.google.com (zps18.corp.google.com [172.25.146.18]) by smtp-out.google.com with ESMTP id mAK1NX82032054 for ; Wed, 19 Nov 2008 17:23:33 -0800 Received: from rv-out-0506.google.com (rvbk40.prod.google.com [10.140.87.40]) by zps18.corp.google.com with ESMTP id mAK1NFY5005326 for ; Wed, 19 Nov 2008 17:23:32 -0800 Received: by rv-out-0506.google.com with SMTP id k40so207397rvb.17 for ; Wed, 19 Nov 2008 17:23:32 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: Date: Wed, 19 Nov 2008 17:23:31 -0800 Message-ID: <6599ad830811191723v3c346a17kf5ae5494987373c1@mail.gmail.com> Subject: Re: [PATCH 1/7] mm: remove cgroup_mm_owner_callbacks From: Paul Menage Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Hugh Dickins Cc: Andrew Morton , Balbir Singh , linux-mm@kvack.org List-ID: On Wed, Nov 19, 2008 at 5:11 PM, Hugh Dickins wrote: > > assign_new_owner: > BUG_ON(c == p); > get_task_struct(c); > - read_unlock(&tasklist_lock); > - down_write(&mm->mmap_sem); > /* > * The task_lock protects c->mm from changing. > * We always want mm->owner->mm == mm > */ > task_lock(c); > + /* > + * Delay read_unlock() till we have the task_lock() > + * to ensure that c does not slip away underneath us > + */ > + read_unlock(&tasklist_lock); How can c slip away when we've done get_task_struct(c) earlier? Paul -- 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