From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 7 May 2008 19:52:56 -0500 From: Robin Holt Subject: Re: [PATCH 08 of 11] anon-vma-rwsem Message-ID: <20080508005256.GB9878@sgi.com> References: <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 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Christoph Lameter , 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, May 07, 2008 at 05:03:30PM -0700, Linus Torvalds wrote: > > > On Wed, 7 May 2008, Christoph Lameter wrote: > > > > Multiple vmas may share the same mapping or refer to the same anonymous > > vma. The above code will deadlock since we may take some locks multiple > > times. > > Ok, so that actually _is_ a problem. It would be easy enough to also add > just a flag to the vma (VM_MULTILOCKED), which is still cleaner than doing > a vmalloc and a whole sort thing, but if this is really rare, maybe Ben's > suggestion of just using stop-machine is actually the right one just > because it's _so_ simple. Also, stop-machine will not work if we come to the conclusion that i_mmap_lock and anon_vma->lock need to be sleepable locks. Thanks, Robin Holt -- 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