Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-12-01 Thread Paul E. McKenney
On Thu, Dec 01, 2016 at 05:41:07PM +0100, Peter Zijlstra wrote: > On Thu, Dec 01, 2016 at 04:33:16AM -0800, Paul E. McKenney wrote: > > On Thu, Dec 01, 2016 at 06:52:35AM +0100, Peter Zijlstra wrote: > > > On Wed, Nov 30, 2016 at 01:13:03PM -0600, Josh Poimboeuf wrote: > > > > This question was pro

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-12-01 Thread Peter Zijlstra
On Thu, Dec 01, 2016 at 04:33:16AM -0800, Paul E. McKenney wrote: > On Thu, Dec 01, 2016 at 06:52:35AM +0100, Peter Zijlstra wrote: > > On Wed, Nov 30, 2016 at 01:13:03PM -0600, Josh Poimboeuf wrote: > > > This question was probably intended for other folks, but I should point > > > out that idle t

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-12-01 Thread Paul E. McKenney
On Thu, Dec 01, 2016 at 06:52:35AM +0100, Peter Zijlstra wrote: > On Wed, Nov 30, 2016 at 01:13:03PM -0600, Josh Poimboeuf wrote: > > This question was probably intended for other folks, but I should point > > out that idle tasks *do* invoke the scheduler. cpu_idle_loop() calls > > schedule_preemp

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-30 Thread Peter Zijlstra
On Wed, Nov 30, 2016 at 01:13:03PM -0600, Josh Poimboeuf wrote: > This question was probably intended for other folks, but I should point > out that idle tasks *do* invoke the scheduler. cpu_idle_loop() calls > schedule_preempt_disabled(). Right, but that doesn't matter I think. The below will si

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-30 Thread Paul E. McKenney
On Wed, Nov 30, 2016 at 01:13:03PM -0600, Josh Poimboeuf wrote: > On Tue, Nov 29, 2016 at 12:32:59PM -0800, Paul E. McKenney wrote: > > On Tue, Nov 29, 2016 at 12:07:11PM -0800, Paul E. McKenney wrote: > > > On Tue, Nov 29, 2016 at 08:52:04PM +0100, Peter Zijlstra wrote: > > > > On Tue, Nov 29, 201

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-30 Thread Josh Poimboeuf
On Tue, Nov 29, 2016 at 12:32:59PM -0800, Paul E. McKenney wrote: > On Tue, Nov 29, 2016 at 12:07:11PM -0800, Paul E. McKenney wrote: > > On Tue, Nov 29, 2016 at 08:52:04PM +0100, Peter Zijlstra wrote: > > > On Tue, Nov 29, 2016 at 11:39:35AM -0800, Paul E. McKenney wrote: > > > > On Tue, Nov 29, 2

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-30 Thread Peter Zijlstra
On Wed, Nov 30, 2016 at 11:01:29AM +0100, Petr Mladek wrote: > On Tue 2016-11-29 18:10:38, Peter Zijlstra wrote: > > In any case, as long as printk has a globally serialized 'log', it, per > > design, will be worse than the console drivers its build upon. And them > > being shit precludes the enti

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-30 Thread Petr Mladek
On Tue 2016-11-29 09:36:00, Paul E. McKenney wrote: > Updated (but still untested) commit below. > > > Thanx, Paul > > > > commit d3df9bc5fb5d838b049f32a476721eadbc3495

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-30 Thread Petr Mladek
On Tue 2016-11-29 18:10:38, Peter Zijlstra wrote: > On Tue, Nov 29, 2016 at 05:29:20PM +0100, Petr Mladek wrote: > > > > > People are very busy polishing the turd we call printk, but from where > > > > I'm sitting its terminally and unfixably broken. > > > > I still hope that we could do better :

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Tue, Nov 29, 2016 at 12:07:11PM -0800, Paul E. McKenney wrote: > On Tue, Nov 29, 2016 at 08:52:04PM +0100, Peter Zijlstra wrote: > > On Tue, Nov 29, 2016 at 11:39:35AM -0800, Paul E. McKenney wrote: > > > On Tue, Nov 29, 2016 at 06:10:38PM +0100, Peter Zijlstra wrote: > > > > > > It mostly work

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Tue, Nov 29, 2016 at 08:52:04PM +0100, Peter Zijlstra wrote: > On Tue, Nov 29, 2016 at 11:39:35AM -0800, Paul E. McKenney wrote: > > On Tue, Nov 29, 2016 at 06:10:38PM +0100, Peter Zijlstra wrote: > > > > It mostly works, most of the time, and that seems to be what Linus > > > wants, since its

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Peter Zijlstra
On Tue, Nov 29, 2016 at 11:39:35AM -0800, Paul E. McKenney wrote: > On Tue, Nov 29, 2016 at 06:10:38PM +0100, Peter Zijlstra wrote: > > It mostly works, most of the time, and that seems to be what Linus > > wants, since its really the best we can have given the constraints. But > > for debugging,

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Tue, Nov 29, 2016 at 06:10:38PM +0100, Peter Zijlstra wrote: > On Tue, Nov 29, 2016 at 05:29:20PM +0100, Petr Mladek wrote: > > > > > People are very busy polishing the turd we call printk, but from where > > > > I'm sitting its terminally and unfixably broken. > > > > I still hope that we cou

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Tue, Nov 29, 2016 at 05:12:46PM +0100, Petr Mladek wrote: > On Tue 2016-11-29 09:09:17, Josh Poimboeuf wrote: > > On Tue, Nov 29, 2016 at 06:07:34AM -0800, Paul E. McKenney wrote: > > > On Tue, Nov 29, 2016 at 10:16:50AM +0100, Peter Zijlstra wrote: > > > > On Mon, Nov 28, 2016 at 11:52:41PM -06

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Tue, Nov 29, 2016 at 11:17:25AM -0600, Josh Poimboeuf wrote: > On Tue, Nov 29, 2016 at 08:51:52AM -0800, Paul E. McKenney wrote: > > On Tue, Nov 29, 2016 at 09:09:17AM -0600, Josh Poimboeuf wrote: > > > On Tue, Nov 29, 2016 at 06:07:34AM -0800, Paul E. McKenney wrote: > > > > On Tue, Nov 29, 201

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Josh Poimboeuf
On Tue, Nov 29, 2016 at 08:51:52AM -0800, Paul E. McKenney wrote: > On Tue, Nov 29, 2016 at 09:09:17AM -0600, Josh Poimboeuf wrote: > > On Tue, Nov 29, 2016 at 06:07:34AM -0800, Paul E. McKenney wrote: > > > On Tue, Nov 29, 2016 at 10:16:50AM +0100, Peter Zijlstra wrote: > > > > On Mon, Nov 28, 201

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Peter Zijlstra
On Tue, Nov 29, 2016 at 05:29:20PM +0100, Petr Mladek wrote: > > > People are very busy polishing the turd we call printk, but from where > > > I'm sitting its terminally and unfixably broken. > > I still hope that we could do better :-) How? The console drivers are a complete trainwreck, you si

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Tue, Nov 29, 2016 at 09:09:17AM -0600, Josh Poimboeuf wrote: > On Tue, Nov 29, 2016 at 06:07:34AM -0800, Paul E. McKenney wrote: > > On Tue, Nov 29, 2016 at 10:16:50AM +0100, Peter Zijlstra wrote: > > > On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > > > > > We used to do that,

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Petr Mladek
On Tue 2016-11-29 07:10:04, Paul E. McKenney wrote: > On Tue, Nov 29, 2016 at 01:43:23PM +0100, Peter Zijlstra wrote: > > On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > > > > > Did a little digging on git blame and found the following commit (which > > > seems to be the cause of

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Petr Mladek
On Tue 2016-11-29 09:09:17, Josh Poimboeuf wrote: > On Tue, Nov 29, 2016 at 06:07:34AM -0800, Paul E. McKenney wrote: > > On Tue, Nov 29, 2016 at 10:16:50AM +0100, Peter Zijlstra wrote: > > > On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > > > > > We used to do that, but the resul

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Josh Poimboeuf
On Tue, Nov 29, 2016 at 06:07:34AM -0800, Paul E. McKenney wrote: > On Tue, Nov 29, 2016 at 10:16:50AM +0100, Peter Zijlstra wrote: > > On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > > > > We used to do that, but the resulting NMIs were problematic on some > > > > platforms. Per

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Tue, Nov 29, 2016 at 01:43:23PM +0100, Peter Zijlstra wrote: > On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > > > Did a little digging on git blame and found the following commit (which > > seems to be the cause of the KASAN warning and missing stack dump): > > > > bc1dce5

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Tue, Nov 29, 2016 at 10:16:50AM +0100, Peter Zijlstra wrote: > On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > > > We used to do that, but the resulting NMIs were problematic on some > > > platforms. Perhaps things have gotten better? > > > > Did a little digging on git blame

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Peter Zijlstra
On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > Did a little digging on git blame and found the following commit (which > seems to be the cause of the KASAN warning and missing stack dump): > > bc1dce514e9b ("rcu: Don't use NMIs to dump other CPUs' stacks") > > I presume this

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Paul E. McKenney
On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > On Mon, Nov 28, 2016 at 04:40:21PM -0800, Paul E. McKenney wrote: > > On Mon, Nov 28, 2016 at 03:54:11PM -0600, Josh Poimboeuf wrote: > > > On Thu, Nov 24, 2016 at 12:33:48PM -0500, Vince Weaver wrote: > > > > > > > > This is on a s

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-29 Thread Peter Zijlstra
On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote: > > We used to do that, but the resulting NMIs were problematic on some > > platforms. Perhaps things have gotten better? > > Did a little digging on git blame and found the following commit (which > seems to be the cause of the KASA

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-28 Thread Josh Poimboeuf
On Mon, Nov 28, 2016 at 04:40:21PM -0800, Paul E. McKenney wrote: > On Mon, Nov 28, 2016 at 03:54:11PM -0600, Josh Poimboeuf wrote: > > On Thu, Nov 24, 2016 at 12:33:48PM -0500, Vince Weaver wrote: > > > > > > This is on a skylake machine, linus git as of yesterday after the various > > > kasan-r

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-28 Thread Paul E. McKenney
On Mon, Nov 28, 2016 at 03:54:11PM -0600, Josh Poimboeuf wrote: > On Thu, Nov 24, 2016 at 12:33:48PM -0500, Vince Weaver wrote: > > > > This is on a skylake machine, linus git as of yesterday after the various > > kasan-related fixes went in. Not sure if there were any that hadn't hit > > upstr

Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start

2016-11-28 Thread Josh Poimboeuf
On Thu, Nov 24, 2016 at 12:33:48PM -0500, Vince Weaver wrote: > > This is on a skylake machine, linus git as of yesterday after the various > kasan-related fixes went in. Not sure if there were any that hadn't hit > upstream yet. > > Anyway I can't tell from this one what the actual trigger is