From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <marcelo@kvack.org>
Subject: Re: [PATCH] replace the slots lock from the mmap_sem to
	private kvm lock
Date: Mon, 11 Feb 2008 15:08:12 -0200
Message-ID: <20080211170812.GA13173@dmt>
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Cc: kvm-devel <kvm-devel@lists.sourceforge.net>,
	Avi Kivity <avi@qumranet.com>
To: Izik Eidus <izike@qumranet.com>
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On Mon, Feb 11, 2008 at 05:12:42PM +0200, Izik Eidus wrote:
> right now kvm take the down_read(mmap_sem) lock to make sure that no 
> slots will be
> removed while trying to get them / make the dirty log safe,
> but in some cases when the down_read(mmap_sem) is called and after that 
> kvm_read_guest() is called
> copy_from_user can result in a page fault that will lead to recursivly 
> taking the mmap_sem,
> 
> this patch remove the mmap_sem, with new kvm private lock.

Hi Izik,

do_mmap/do_munmap requires the mmap_sem in write-mode.

I couldnt find any sequence which grabs mmap_sem and then slots_lock,
but it would be nice to verify again that can't happen.

Other than that looks good.


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