On 01/14/2016 03:04 PM, Michael S. Tsirkin wrote:
> KASan detected a use-after-free error in virtio-pci remove code. In
> virtio_pci_remove(), vp_dev is still used after being freed in
> unregister_virtio_device() (in virtio_pci_release_dev() more
> precisely).
>
> To fix, keep a reference until
Hi Michael,
KASan detected a use-after-free error in virtio-pci remove code. In
virtio_pci_remove(), vp_dev is still used after being freed in
unregister_virtio_device() (in virtio_pci_release_dev() more
precisely). I don't know the proper way to fix this.
Here is the KASan output:
[
On Thu, Jan 14, 2016 at 12:04:45PM +, Will Deacon wrote:
> On Wed, Jan 13, 2016 at 12:58:22PM -0800, Leonid Yegoshin wrote:
> > On 01/13/2016 12:48 PM, Peter Zijlstra wrote:
> > >On Wed, Jan 13, 2016 at 11:02:35AM -0800, Leonid Yegoshin wrote:
> > >
> > >>I ask HW team about it but I have a
On Wed, Jan 13, 2016 at 02:26:16PM -0800, Leonid Yegoshin wrote:
> And all that is out-of-topic here in my mind. I just want to be sure that
> this patchset still provides a use of a specific lightweight SYNCs on MIPS
> vs bold and heavy generalized "SYNC 0" in any case.
>
> - Leonid.
Of course
On Wed, Jan 13, 2016 at 10:12:22PM +0200, Michael S. Tsirkin wrote:
> mb() typically uses mfence on modern x86, but a micro-benchmark shows that
> it's
> 2 to 3 times slower than lock; addl that we use on older CPUs.
>
> So let's use the locked variant everywhere.
>
> While I was at it, I found
On Wed, Jan 13, 2016 at 12:58:22PM -0800, Leonid Yegoshin wrote:
> On 01/13/2016 12:48 PM, Peter Zijlstra wrote:
> >On Wed, Jan 13, 2016 at 11:02:35AM -0800, Leonid Yegoshin wrote:
> >
> >>I ask HW team about it but I have a question - has it any relationship with
> >>replacing MIPS SYNC with
KASan detected a use-after-free error in virtio-pci remove code. In
virtio_pci_remove(), vp_dev is still used after being freed in
unregister_virtio_device() (in virtio_pci_release_dev() more
precisely).
To fix, keep a reference until cleanup is done.
Fixes: 63bd62a08ca4 ("virtio_pci: defer
On Thu, Jan 14, 2016 at 02:25:50PM +0100, Jerome Marchand wrote:
> Hi Michael,
>
> KASan detected a use-after-free error in virtio-pci remove code. In
> virtio_pci_remove(), vp_dev is still used after being freed in
> unregister_virtio_device() (in virtio_pci_release_dev() more
> precisely). I
On Thu, Jan 14, 2016 at 01:36:50PM -0800, Leonid Yegoshin wrote:
> On 01/14/2016 01:29 PM, Paul E. McKenney wrote:
> >
> >>On 01/14/2016 12:34 PM, Paul E. McKenney wrote:
> >>>
> >>>The WRC+addr+addr is OK because data dependencies are not required to be
> >>>transitive, in other words, they are
On 01/14/2016 02:24 PM, Paul E. McKenney wrote:
Actually, the Linux kernel doesn't have an acquire barrier, just an
smp_load_acquire(). Or did someone sneak one in while I wasn't looking?
That was an exactly starting point for this discussion. This patch just
pulls out from MIPS files
On 01/14/2016 02:55 PM, Paul E. McKenney wrote:
OK, so it looks like Will was asking not about WRC+addr+addr, but instead
about WRC+sync+addr.
(He actually asked twice about this and that too but skip this)
I am guessing that the manual's "Older instructions which must be globally
performed
On Thu, Jan 14, 2016 at 01:45:44PM -0800, Leonid Yegoshin wrote:
> On 01/14/2016 01:34 PM, Paul E. McKenney wrote:
> >On Thu, Jan 14, 2016 at 12:46:43PM -0800, Leonid Yegoshin wrote:
> >>On 01/14/2016 12:15 PM, Peter Zijlstra wrote:
> >>>On Thu, Jan 14, 2016 at 11:42:02AM -0800, Leonid Yegoshin
On Thu, Jan 14, 2016 at 03:33:40PM -0800, Leonid Yegoshin wrote:
> On 01/14/2016 02:55 PM, Paul E. McKenney wrote:
> >OK, so it looks like Will was asking not about WRC+addr+addr, but instead
> >about WRC+sync+addr.
> (He actually asked twice about this and that too but skip this)
Fair enough!
On 01/14/2016 04:14 AM, Will Deacon wrote:
On Wed, Jan 13, 2016 at 02:26:16PM -0800, Leonid Yegoshin wrote:
Moreover, there are voices against guarantee that it will be in future
and that voices point me to Documentation/memory-barriers.txt section "DATA
DEPENDENCY BARRIERS" examples
On 01/14/2016 08:16 AM, Paul E. McKenney wrote:
On Thu, Jan 14, 2016 at 12:04:45PM +, Will Deacon wrote:
On Wed, Jan 13, 2016 at 12:58:22PM -0800, Leonid Yegoshin wrote:
On 01/13/2016 12:48 PM, Peter Zijlstra wrote:
On Wed, Jan 13, 2016 at 11:02:35AM -0800, Leonid Yegoshin wrote:
I ask
On Thu, Jan 14, 2016 at 01:24:34PM -0800, Leonid Yegoshin wrote:
> On 01/14/2016 12:48 PM, Paul E. McKenney wrote:
> >
> >So SYNC_RMB is intended to implement smp_rmb(), correct?
> Yes.
> >
> >You could use SYNC_ACQUIRE() to implement read_barrier_depends() and
> >smp_read_barrier_depends(), but
On 01/14/2016 04:47 PM, Paul E. McKenney wrote:
On Thu, Jan 14, 2016 at 03:33:40PM -0800, Leonid Yegoshin wrote:
Don't be fooled here by words "ordered" and "completed" - it is HW
design items and actually written poorly.
Just assume that SYNC_MB is absolutely the same as SYNC for any CPU
and
On 01/14/2016 04:04 AM, Will Deacon wrote:
Consequently, it's important that the architecture back-ends implement
these portable primitives (e.g. smp_mb()) in a way that satisfies the
kernel memory model so that core code doesn't need to worry about the
underlying architecture for
On Thu, Jan 14, 2016 at 12:46:43PM -0800, Leonid Yegoshin wrote:
> On 01/14/2016 12:15 PM, Peter Zijlstra wrote:
> >On Thu, Jan 14, 2016 at 11:42:02AM -0800, Leonid Yegoshin wrote:
> >>An the only point - please use an appropriate SYNC_* barriers instead of
> >>heavy bold hammer. That stuff was
On Thu, Jan 14, 2016 at 01:01:05PM -0800, Leonid Yegoshin wrote:
> I need some time to understand your test examples. However,
Understood.
> On 01/14/2016 12:34 PM, Paul E. McKenney wrote:
> >
> >
> >The WRC+addr+addr is OK because data dependencies are not required to be
> >transitive, in other
On 01/14/2016 12:15 PM, Peter Zijlstra wrote:
On Thu, Jan 14, 2016 at 11:42:02AM -0800, Leonid Yegoshin wrote:
An the only point - please use an appropriate SYNC_* barriers instead of
heavy bold hammer. That stuff was design explicitly to support the
requirements of
On Thu, Jan 14, 2016 at 09:15:13PM +0100, Peter Zijlstra wrote:
> On Thu, Jan 14, 2016 at 11:42:02AM -0800, Leonid Yegoshin wrote:
> > An the only point - please use an appropriate SYNC_* barriers instead of
> > heavy bold hammer. That stuff was design explicitly to support the
> > requirements of
On Thu, Jan 14, 2016 at 12:12:53PM -0800, Leonid Yegoshin wrote:
> On 01/14/2016 04:04 AM, Will Deacon wrote:
> >Consequently, it's important that the architecture back-ends
> >implement these portable primitives (e.g. smp_mb()) in a way that
> >satisfies the kernel memory model so that core code
I need some time to understand your test examples. However,
On 01/14/2016 12:34 PM, Paul E. McKenney wrote:
The WRC+addr+addr is OK because data dependencies are not required to be
transitive, in other words, they are not required to flow from one CPU to
another without the help of an
On Thu, Jan 14, 2016 at 11:42:02AM -0800, Leonid Yegoshin wrote:
> An the only point - please use an appropriate SYNC_* barriers instead of
> heavy bold hammer. That stuff was design explicitly to support the
> requirements of Documentation/memory-barriers.txt
That's madness. That document
On Thu, Jan 14, 2016 at 11:28:18AM -0800, Leonid Yegoshin wrote:
> On 01/14/2016 04:14 AM, Will Deacon wrote:
> >On Wed, Jan 13, 2016 at 02:26:16PM -0800, Leonid Yegoshin wrote:
> >
> >> Moreover, there are voices against guarantee that it will be in future
> >>and that voices point me to
On Thu, Jan 14, 2016 at 09:15:13PM +0100, Peter Zijlstra wrote:
> On Thu, Jan 14, 2016 at 11:42:02AM -0800, Leonid Yegoshin wrote:
> > An the only point - please use an appropriate SYNC_* barriers instead of
> > heavy bold hammer. That stuff was design explicitly to support the
> > requirements of
On 01/14/2016 01:34 PM, Paul E. McKenney wrote:
On Thu, Jan 14, 2016 at 12:46:43PM -0800, Leonid Yegoshin wrote:
On 01/14/2016 12:15 PM, Peter Zijlstra wrote:
On Thu, Jan 14, 2016 at 11:42:02AM -0800, Leonid Yegoshin wrote:
An the only point - please use an appropriate SYNC_* barriers instead
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