On Tue, May 21, 2013 at 01:57:34PM +0200, Peter Zijlstra wrote:
> On Sun, May 19, 2013 at 12:35:26PM +0300, Michael S. Tsirkin wrote:
> > > > --- a/include/linux/kernel.h
> > > > +++ b/include/linux/kernel.h
> > > > @@ -198,7 +198,6 @@ void might_fault(void);
> > > > #else
> > > > static inline v
On Thu, May 16, 2013 at 08:40:41PM +0200, Peter Zijlstra wrote:
> On Thu, May 16, 2013 at 02:16:10PM +0300, Michael S. Tsirkin wrote:
> > There are several ways to make sure might_fault
> > calling function does not sleep.
> > One is to use it on kernel or otherwise locked memory - apparently
> > n
On Wed, May 22, 2013 at 12:47:09PM +0300, Michael S. Tsirkin wrote:
> >
> > +static inline bool __can_fault(void)
> > +{
> > + /*
> > +* Some code (nfs/sunrpc) uses socket ops on kernel memory while
> > +* holding the mmap_sem, this is safe because kernel memory doesn't
> > +* get p
On Tue, May 21, 2013 at 01:57:34PM +0200, Peter Zijlstra wrote:
> On Sun, May 19, 2013 at 12:35:26PM +0300, Michael S. Tsirkin wrote:
> > > > --- a/include/linux/kernel.h
> > > > +++ b/include/linux/kernel.h
> > > > @@ -198,7 +198,6 @@ void might_fault(void);
> > > > #else
> > > > static inline v
On Sun, May 19, 2013 at 12:35:26PM +0300, Michael S. Tsirkin wrote:
> On Thu, May 16, 2013 at 08:40:41PM +0200, Peter Zijlstra wrote:
> > On Thu, May 16, 2013 at 02:16:10PM +0300, Michael S. Tsirkin wrote:
> > > There are several ways to make sure might_fault
> > > calling function does not sleep.
On Sun, May 19, 2013 at 12:35:26PM +0300, Michael S. Tsirkin wrote:
> > > --- a/include/linux/kernel.h
> > > +++ b/include/linux/kernel.h
> > > @@ -198,7 +198,6 @@ void might_fault(void);
> > > #else
> > > static inline void might_fault(void)
> > > {
> > > - might_sleep();
> >
> > This removes
On Sun, May 19, 2013 at 07:40:09PM +0300, Michael S. Tsirkin wrote:
> OK I get it. So let me correct myself. The simple code
> that does something like this under a spinlock:
> > preempt_disable
> > pagefault_disable
> > error = copy_to_user
> > pagefault_enable
> > pr
On Sun, May 19, 2013 at 04:23:22PM -0400, Steven Rostedt wrote:
> On Sun, 2013-05-19 at 19:40 +0300, Michael S. Tsirkin wrote:
>
> > OK I get it. So let me correct myself. The simple code
> > that does something like this under a spinlock:
> > > preempt_disable
> > > pagefault_disable
On Sun, 2013-05-19 at 19:40 +0300, Michael S. Tsirkin wrote:
> OK I get it. So let me correct myself. The simple code
> that does something like this under a spinlock:
> > preempt_disable
> > pagefault_disable
> > error = copy_to_user
> > pagefault_enable
> > preempt_
On Sun, May 19, 2013 at 12:06:19PM -0400, Steven Rostedt wrote:
> On Sun, 2013-05-19 at 16:34 +0300, Michael S. Tsirkin wrote:
>
> > Right but we need to keep it working on upstream as well.
> > If I do preempt_enable under a spinlock upstream won't it
> > try to sleep under spinlock?
>
> No it w
On Sun, 2013-05-19 at 16:34 +0300, Michael S. Tsirkin wrote:
> Right but we need to keep it working on upstream as well.
> If I do preempt_enable under a spinlock upstream won't it
> try to sleep under spinlock?
No it wont. A spinlock calls preempt_disable implicitly, and a
preempt_enable() will
On Sun, May 19, 2013 at 08:34:04AM -0400, Steven Rostedt wrote:
> On Sun, 2013-05-19 at 12:35 +0300, Michael S. Tsirkin wrote:
>
> > No, I was not assuming that. What I'm trying to say is that a caller
> > that does something like this under a spinlock:
> > preempt_disable
> > pagefault_di
On Sun, 2013-05-19 at 12:35 +0300, Michael S. Tsirkin wrote:
> No, I was not assuming that. What I'm trying to say is that a caller
> that does something like this under a spinlock:
> preempt_disable
> pagefault_disable
> error = copy_to_user
> pagefault_enable
> pree
On Thu, May 16, 2013 at 08:40:41PM +0200, Peter Zijlstra wrote:
> On Thu, May 16, 2013 at 02:16:10PM +0300, Michael S. Tsirkin wrote:
> > There are several ways to make sure might_fault
> > calling function does not sleep.
> > One is to use it on kernel or otherwise locked memory - apparently
> > n
On Thu, May 16, 2013 at 02:16:10PM +0300, Michael S. Tsirkin wrote:
> There are several ways to make sure might_fault
> calling function does not sleep.
> One is to use it on kernel or otherwise locked memory - apparently
> nfs/sunrpc does this. As noted by Ingo, this is handled by the
> migh_fault
There are several ways to make sure might_fault
calling function does not sleep.
One is to use it on kernel or otherwise locked memory - apparently
nfs/sunrpc does this. As noted by Ingo, this is handled by the
migh_fault() implementation in mm/memory.c but not the one in
linux/kernel.h so in the c
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