From: Ian Campbell <Ian.Campbell@citrix.com>
To: Andres Lagar-Cavilla <andreslc@gridcentric.ca>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
David Vrabel <david.vrabel@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH 2/2] xen/privcmd: add PRIVCMD_MMAPBATCH_V2 ioctl
Date: Fri, 31 Aug 2012 08:02:12 +0100 [thread overview]
Message-ID: <1346396532.5820.1.camel@dagon.hellion.org.uk> (raw)
In-Reply-To: <165680AD-2970-4A8D-BEC0-B02830F8A97F@gridcentric.ca>
On Thu, 2012-08-30 at 19:29 +0100, Andres Lagar-Cavilla wrote:
> On Aug 30, 2012, at 1:04 PM, David Vrabel wrote:
> > You can't access user space pages here while holding
> > current->mm->mmap_sem. I tried this and it would sometimes deadlock in
> > the page fault handler.
> >
> > access_ok() only checks if the pointer is in the user space virtual
> > address space - not that a valid mapping exists and is writable. So
> > BUG_ON(__put_user()) should not be done.
>
> Very true. Thanks for the pointer. Clearly the reason for the gather_array/traverse_pages structure.
/me has flashbacks to the mammoth debugging session which led to
http://xenbits.xen.org/hg/linux-2.6.18-xen.hg/rev/043dc7488c11.
Ian.
next prev parent reply other threads:[~2012-08-31 7:02 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-30 12:58 [PATCHv3 0/2] xen/privcmd: support for paged-out frames David Vrabel
2012-08-30 12:58 ` [PATCH 1/2] xen/mm: return more precise error from xen_remap_domain_range() David Vrabel
2012-08-30 15:07 ` Andres Lagar-Cavilla
2012-08-30 12:58 ` [PATCH 2/2] xen/privcmd: add PRIVCMD_MMAPBATCH_V2 ioctl David Vrabel
2012-08-30 16:41 ` Andres Lagar-Cavilla
2012-08-30 17:04 ` David Vrabel
2012-08-30 18:29 ` Andres Lagar-Cavilla
2012-08-31 7:02 ` Ian Campbell [this message]
2012-08-30 18:32 ` Andres Lagar-Cavilla
2012-08-31 13:08 ` David Vrabel
2012-08-31 13:13 ` Andres Lagar-Cavilla
2012-09-05 16:17 ` Konrad Rzeszutek Wilk
2012-08-31 13:59 ` Andres Lagar-Cavilla
2012-09-05 16:21 ` Konrad Rzeszutek Wilk
2012-09-05 17:09 ` Andres Lagar-Cavilla
2012-09-05 17:40 ` Konrad Rzeszutek Wilk
2012-09-06 13:41 ` Andres Lagar-Cavilla
2012-09-06 16:20 ` Konrad Rzeszutek Wilk
2012-08-30 20:05 ` [PATCHv3 0/2] xen/privcmd: support for paged-out frames Konrad Rzeszutek Wilk
2012-08-30 20:12 ` Andres Lagar-Cavilla
2012-09-05 18:57 ` Konrad Rzeszutek Wilk
2012-09-05 19:51 ` Andres Lagar-Cavilla
2012-09-05 20:05 ` Konrad Rzeszutek Wilk
-- strict thread matches above, loose matches on Subject: below --
2012-08-29 13:15 [PATCHv2 " David Vrabel
2012-08-29 13:15 ` [PATCH 2/2] xen/privcmd: add PRIVCMD_MMAPBATCH_V2 ioctl David Vrabel
2012-08-29 16:14 ` Andres Lagar-Cavilla
2012-08-29 16:36 ` David Vrabel
2012-08-29 18:10 ` Andres Lagar-Cavilla
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