From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: [Ksummit-2005-discuss] Summary of 2005 Kernel Summit Proposed Topics Date: Wed, 30 Mar 2005 17:33:13 +0200 Message-ID: <20050330153313.GD32111@g5.random> References: <20050327054831.GA15453@waste.org> <1111905181.4753.15.camel@mylaptop> <20050326224621.61f6d917.davem@davemloft.net> <1112027284.5531.27.camel@mulgrave> <20050329152008.GD63268@muc.de> <1112116762.5088.65.camel@beastie> <1112130512.1077.107.camel@jzny.localdomain> <20050330152208.GB12672@muc.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: jamal , Dmitry Yusupov , James Bottomley , Rik van Riel , mpm@selenic.com, michaelc@cs.wisc.edu, open-iscsi@googlegroups.com, ksummit-2005-discuss@thunk.org, netdev Return-path: To: Andi Kleen Content-Disposition: inline In-Reply-To: <20050330152208.GB12672@muc.de> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Wed, Mar 30, 2005 at 05:22:08PM +0200, Andi Kleen wrote: > Which I think is pretty unlikely. Normally the dirty limits in the VM > should prevent it anyways - VM is supposed to block before all > your memory is dirty. The CPU can still dirty pages in user space, This is not true for MAP_SHARED as I mentioned earlier in this thread. The dirty limits can't trigger unless you want to take a page fault for every single memory write opcode that touches a clean page (and as well marking the pte clean and wrprotect during writepage). And we're not going to change anything for swap and anon/shm, so it would be still an issue for swap over iscsi. You can be right the receive path may be less of a pratical issue, but it's still very much an at least theoretical source of deadlock.