From mboxrd@z Thu Jan 1 00:00:00 1970 In-reply-to: <1175765760.6483.93.camel@twins> (message from Peter Zijlstra on Thu, 05 Apr 2007 11:36:00 +0200) Subject: Re: [patch 2/2] only allow nonlinear vmas for ram backed filesystems References: <1175765760.6483.93.camel@twins> Message-Id: From: Miklos Szeredi Date: Thu, 05 Apr 2007 11:39:52 +0200 Sender: owner-linux-mm@kvack.org Return-Path: To: a.p.zijlstra@chello.nl Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: > > + /* > > + * page_mkclean doesn't work on nonlinear vmas, so if dirty > > + * pages need to be accounted, emulate with linear vmas. > > + */ > > + if (mapping_cap_account_dirty(mapping)) { > > Perhaps this should read: > > if (vma_wants_writenotify(vma)) { > I looked at that, but IIRC vma_wants_writenotify() doesn't work after mmap(), because of the updated protection bits. > That way we would even allow read only non-linear mappings of 'real' > filesystem files. Well, we could do that, but is it really worth the hassle? The real question is whether anyone would want to use non-linear shared-read-only mappings or not. Thanks, Miklos -- 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