Re: [PATCH 1/4] rcu: Allow for page faults in NMI handlers

2017-09-25 Thread Paul E. McKenney
On Sun, Sep 24, 2017 at 09:56:32PM -0700, Paul E. McKenney wrote: > On Mon, Sep 25, 2017 at 06:41:30AM +0200, Steven Rostedt wrote: > > Sorry for the top post, currently on a train to Paris. > > > > This series already went through all my testing, and I would hate to rebase > > it for this reason

Re: [PATCH 1/4] rcu: Allow for page faults in NMI handlers

2017-09-24 Thread Paul E. McKenney
On Mon, Sep 25, 2017 at 06:41:30AM +0200, Steven Rostedt wrote: > Sorry for the top post, currently on a train to Paris. > > This series already went through all my testing, and I would hate to rebase > it for this reason. Can you just add a patch to remove the READ_ONCE()s? If Linus accepts the

Re: [PATCH 1/4] rcu: Allow for page faults in NMI handlers

2017-09-24 Thread Steven Rostedt
Sorry for the top post, currently on a train to Paris. This series already went through all my testing, and I would hate to rebase it for this reason. Can you just add a patch to remove the READ_ONCE()s? Thanks, -- Steve On September 25, 2017 2:34:56 AM GMT+02:00, "Paul E. McKenney" wrote:

Re: [PATCH 1/4] rcu: Allow for page faults in NMI handlers

2017-09-24 Thread Paul E. McKenney
On Sun, Sep 24, 2017 at 05:26:53PM -0700, Paul E. McKenney wrote: > On Sun, Sep 24, 2017 at 05:12:13PM -0700, Linus Torvalds wrote: > > On Sun, Sep 24, 2017 at 5:03 PM, Paul E. McKenney > > wrote: > > > > > > Mostly just paranoia on my part. I would be happy to remove it if > > > you prefer. Or

Re: [PATCH 1/4] rcu: Allow for page faults in NMI handlers

2017-09-24 Thread Paul E. McKenney
On Sun, Sep 24, 2017 at 05:12:13PM -0700, Linus Torvalds wrote: > On Sun, Sep 24, 2017 at 5:03 PM, Paul E. McKenney > wrote: > > > > Mostly just paranoia on my part. I would be happy to remove it if > > you prefer. Or you or Steve can do so if that is more convenient. > > I really don't think i

Re: [PATCH 1/4] rcu: Allow for page faults in NMI handlers

2017-09-24 Thread Linus Torvalds
On Sun, Sep 24, 2017 at 5:03 PM, Paul E. McKenney wrote: > > Mostly just paranoia on my part. I would be happy to remove it if > you prefer. Or you or Steve can do so if that is more convenient. I really don't think it's warranted. The values are *stable*. There's no subtle lack of locking, or

Re: [PATCH 1/4] rcu: Allow for page faults in NMI handlers

2017-09-24 Thread Paul E. McKenney
On Sun, Sep 24, 2017 at 12:42:32PM -0700, Linus Torvalds wrote: > On Sat, Sep 23, 2017 at 1:56 PM, Steven Rostedt wrote: > > + > > + /* Page faults can happen in NMI handlers, so check... */ > > + if (READ_ONCE(rdtp->dynticks_nmi_nesting)) > > + return; > > + > > What is

Re: [PATCH 1/4] rcu: Allow for page faults in NMI handlers

2017-09-24 Thread Linus Torvalds
On Sat, Sep 23, 2017 at 1:56 PM, Steven Rostedt wrote: > + > + /* Page faults can happen in NMI handlers, so check... */ > + if (READ_ONCE(rdtp->dynticks_nmi_nesting)) > + return; > + What is the reason for the READ_ONCE() here (and in the other case)? It doesn't seem t