From mboxrd@z Thu Jan 1 00:00:00 1970 From: KOSAKI Motohiro Subject: Re: [GIT PULL] please pull ummunotify Date: Fri, 11 Sep 2009 15:21:35 +0900 (JST) Message-ID: <20090911151930.DB6B.A69D9226@jp.fujitsu.com> References: <4AA9EAF7.5010401@inria.fr> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4AA9EAF7.5010401-MZpvjPyXg2s@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Brice Goglin Cc: kosaki.motohiro-+CUm20s59erQFUHtdCDX3A@public.gmane.org, Roland Dreier , torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, jsquyres-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, general-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org > Roland Dreier wrote: > > > Can I this version already solved fork() + COW issue? if so, could you > > > please explain what happen at fork. Obviously RDMA point to either parent > > > or child page, not both. but Corrent COW rule is, first touch process > > > get copyed page and other process still own original page. I think it's > > > unpecected behavior form RDMA. > > > > No, ummunotify doesn't really help that much with fork() + COW. If a > > parent forks and then touches pages that are actively in use for RDMA, > > then of course they get COWed and RDMA goes to the wrong memory (from > > the point of view of the parent). > > > > My understanding of the code is that fork will end-up calling > copy_page_range() on all VMA, and copy_page_range() calls > mmu_notifier_invalidate_range_start() if is_cow_mapping() is true, > which should be the case here. So you should get some invalidate events > on fork. Worried... Anybody haven't test fork() case yet??? -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html