On Thu, Oct 22, 2015 at 04:18:31PM +0200, Andrea Arcangeli wrote:
> The risk of memory corruption is still zero no matter what happens
> here, in the extremely rare case the app will get a SIGBUS or a
That might still upset people, SIGBUS isn't something an app can really
recover from.
> I'm not
On Thu, Oct 22, 2015 at 05:15:09PM +0200, Peter Zijlstra wrote:
> Indefinitely is such a long time, we should try and finish
> computation before the computer dies etc. :-)
Indefinitely as read_seqcount_retry, eventually it makes progress.
Even returning 0 from the page fault can trigger it again
On Thu, Oct 22, 2015 at 03:38:24PM +0200, Peter Zijlstra wrote:
> On Thu, Oct 22, 2015 at 03:20:15PM +0200, Andrea Arcangeli wrote:
>
> > If schedule spontaneously wakes up a task in TASK_KILLABLE state that
> > would be a bug in the scheduler in my view. Luckily there doesn't seem
> > to be such
On Thu, Oct 22, 2015 at 03:20:15PM +0200, Andrea Arcangeli wrote:
> If schedule spontaneously wakes up a task in TASK_KILLABLE state that
> would be a bug in the scheduler in my view. Luckily there doesn't seem
> to be such a bug, or at least we never experienced it.
Well, there will be a wakeup,
On Thu, Oct 22, 2015 at 02:10:56PM +0200, Peter Zijlstra wrote:
> On Thu, May 14, 2015 at 07:31:11PM +0200, Andrea Arcangeli wrote:
> > @@ -255,21 +259,23 @@ int handle_userfault(struct vm_area_struct *vma,
> > unsigned long address,
> > * through poll/read().
> > */
> > __add_wait_q
On Thu, May 14, 2015 at 07:31:11PM +0200, Andrea Arcangeli wrote:
> @@ -255,21 +259,23 @@ int handle_userfault(struct vm_area_struct *vma,
> unsigned long address,
>* through poll/read().
>*/
> __add_wait_queue(&ctx->fault_wqh, &uwq.wq);
> - for (;;) {
> - set
This is an optimization but it's a userland visible one and it affects
the API.
The downside of this optimization is that if you call poll() and you
get POLLIN, read(ufd) may still return -EAGAIN. The blocked userfault
may be waken by a different thread, before read(ufd) comes
around. This in shor
