From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 27 Feb 2006 17:23:09 +0000 (GMT) From: Hugh Dickins Subject: Re: page_lock_anon_vma(): remove check for mapped page In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: akpm@osdl.org, linux-mm@kvack.org List-ID: On Mon, 27 Feb 2006, Christoph Lameter wrote: > > That is a rather subtle thing not evident from the code. Add another > comment? I won't fight if you insist on doing so, but it's already proclaimed itself to be tricky, with lengthy comments in mm/slab.c and now here. At some stage, I think, we need to stop reading comments and ponder the code itself. > Or better do the rcu locking before calling page_lock_anon_vma > and the unlocking after spin_unlock to have proper nesting of locks? No, page_lock_anon_vma is all about insulating the rest of the code from these difficulties: I do prefer it as is. That said, I had mixed feelings when the name "rcu_read_lock" was introduced: it's not always helpful to distinguish it from preempt_disable in that way. Hugh -- 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