From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 7 May 2008 18:39:48 -0700 (PDT) From: Linus Torvalds Subject: Re: [PATCH 08 of 11] anon-vma-rwsem In-Reply-To: Message-ID: References: <6b384bb988786aa78ef0.1210170958@duo.random> <20080507212650.GA8276@duo.random> <20080507222205.GC8276@duo.random> <20080507153103.237ea5b6.akpm@linux-foundation.org> <20080507224406.GI8276@duo.random> <20080507155914.d7790069.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Andrew Morton , Andrea Arcangeli , steiner@sgi.com, holt@sgi.com, npiggin@suse.de, a.p.zijlstra@chello.nl, kvm-devel@lists.sourceforge.net, kanojsarcar@yahoo.com, rdreier@cisco.com, swise@opengridcomputing.com, linux-kernel@vger.kernel.org, avi@qumranet.com, linux-mm@kvack.org, general@lists.openfabrics.org, hugh@veritas.com, rusty@rustcorp.com.au, aliguori@us.ibm.com, chrisw@redhat.com, marcelo@kvack.org, dada1@cosmosbay.com, paulmck@us.ibm.com List-ID: On Wed, 7 May 2008, Christoph Lameter wrote: > > > (That said, we're not running out of vm flags yet, and if we were, we > > could just add another word. We're already wasting that space right now on > > 64-bit by calling it "unsigned long"). > > We sure have enough flags. Oh, btw, I was wrong - we wouldn't want to mark the vma's (they are unique), we need to mark the address spaces/anonvma's. So the flag would need to be in the "struct anon_vma" (and struct address_space), not in the vma itself. My bad. So the flag wouldn't be one of the VM_xyzzy flags, and would require adding a new field to "struct anon_vma()" And related to that brain-fart of mine, that obviously also means that yes, the locking has to be stronger than "mm->mmap_sem" held for writing, so yeah, it would have be a separate global spinlock (or perhaps a blocking lock if you have some reason to protect anything else with this too). Linus -- 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