Messages in this thread | | | Date | Mon, 19 Mar 2012 17:34:49 +0800 | From | Xiao Guangrong <> | Subject | Re: [PATCH 3/4] KVM: Switch to srcu-less get_dirty_log() |
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On 03/16/2012 05:44 PM, Takuya Yoshikawa wrote:
> On Fri, 16 Mar 2012 16:28:56 +0800 > Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> wrote: > >> Thanks for your explanation, maybe you are right, i do not know migration >> much. >> >> What i worried about is, you have changed the behaviour of GET_DIRTY_LOG, >> in the current one, it can get all the dirty pages when it is called; after >> your change, GET_DIRTY_LOG can get a empty dirty bitmap but dirty page exists. > > The current code also see the same situation because nothing prevents the > guest from writing to pages before GET_DIRTY_LOG returns and the userspace > checks the bitmap. Everything is running. >
The current code is under the protection of s-rcu: IIRC, it always holds s-rcu when write guest page and set dirty bit, that mean the dirty page is logged either in the old dirty_bitmap or in the current memslot->dirty_bitmap. Yes?
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