From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 0D2346B003D for ; Thu, 2 Apr 2009 09:36:35 -0400 (EDT) Message-ID: <49D4BE64.8020508@redhat.com> Date: Thu, 02 Apr 2009 16:32:20 +0300 From: Izik Eidus MIME-Version: 1.0 Subject: Re: [PATCH 5/4] update ksm userspace interfaces References: <20090331142533.GR9137@random.random> <49D22A9D.4050403@codemonkey.ws> <20090331150218.GS9137@random.random> <49D23224.9000903@codemonkey.ws> <20090331151845.GT9137@random.random> <49D23CD1.9090208@codemonkey.ws> <20090331162525.GU9137@random.random> <49D24A02.6070000@codemonkey.ws> <20090402012215.GE1117@x200.localdomain> <49D424AF.3090806@codemonkey.ws> <20090402053114.GF1117@x200.localdomain> In-Reply-To: <20090402053114.GF1117@x200.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Chris Wright Cc: Anthony Liguori , Andrea Arcangeli , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, avi@redhat.com, riel@redhat.com, jeremy@goop.org, mtosatti@redhat.com, hugh@veritas.com, corbet@lwn.net, yaniv@redhat.com, dmonakhov@openvz.org List-ID: Chris Wright wrote: > * Anthony Liguori (anthony@codemonkey.ws) wrote: > >> Using an interface like madvise() would force the issue to be dealt with >> properly from the start :-) >> > > Yeah, I'm not at all opposed to it. > > This updates to madvise for register and sysfs for control. > > madvise issues: > - MADV_SHAREABLE > - register only ATM, can add MADV_UNSHAREABLE to allow an app to proactively > unregister, but need a cleanup when ->mm goes away via exit/exec > - will register a region per vma, should probably push the whole thing > into vma rather than keep [mm,addr,len] tuple in ksm > > The main problem that ksm will face when removing the fd interface is: right now when you register memory into ksm, you open fd, and then ksm do get_task_mm(), we will do mmput when the file will be closed (note that this doesnt mean that if you fork and not close the fd the memory wont go away...., get_task_mm() doesnt protect the vmas inside the mm strcture and therefore they will be able to get removed) So if we move into madvice and we remove the get_task_mm() usage, we will have to add notification to exit_mm() so ksm will know it should stop using this mm strcture, and drop it from all the trees data... Is this what we want? -- 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