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Groups > linux.kernel > #1534311
| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start |
| Date | 2016-12-01 18:10 +0100 |
| Message-ID | <sJD1U-70r-33@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <sIXm1-4RO-21@gated-at.bofh.it> <sJiAa-1FU-11@gated-at.bofh.it> <sJszw-87u-7@gated-at.bofh.it> <sJyOC-3S3-45@gated-at.bofh.it> <sJCIy-6wt-13@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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 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 simply not call
> > > rcu_note_voluntary_context_switch() from the idle task, which would be
> > > fine I think.
> > >
> > > > > So is the following a sensible approach, or should I look elsewhere?
> > > > >
> > > > > #define cond_resched_rcu_qs() \
> > > > > do { \
> > > > > if (!is_idle_task(current) && !cond_resched()) \
> > > > > rcu_note_voluntary_context_switch(current); \
> > >
> > > You should reverse your conditions though:
> > >
> > > if (!cond_resched() && !is_idle_task(current))
> > > rcu_note_voluntary_context_switch(current);
> > >
> > > That way we'll still do cond_resched() and you only gate the RCU call.
> >
> > This makes it illegal at early boot.
>
> Humm, how early are we talking?
The case I saw was during start_kernel(), IIRC. But again, it turned
out that the patch putting cond_resched_rcu_qs() in that early was
(1) broken and (2) unnecessary.
Thanx, Paul
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Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Josh Poimboeuf <jpoimboe@redhat.com> - 2016-11-28 23:00 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 01:50 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Josh Poimboeuf <jpoimboe@redhat.com> - 2016-11-29 07:00 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Peter Zijlstra <peterz@infradead.org> - 2016-11-29 10:20 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 15:10 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Josh Poimboeuf <jpoimboe@redhat.com> - 2016-11-29 16:10 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Petr Mladek <pmladek@suse.com> - 2016-11-29 17:20 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 19:10 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 18:00 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Josh Poimboeuf <jpoimboe@redhat.com> - 2016-11-29 18:20 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 18:40 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Petr Mladek <pmladek@suse.com> - 2016-11-30 11:00 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 11:30 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Peter Zijlstra <peterz@infradead.org> - 2016-11-29 13:50 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 16:20 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Petr Mladek <pmladek@suse.com> - 2016-11-29 17:30 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Peter Zijlstra <peterz@infradead.org> - 2016-11-29 18:20 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 20:50 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Peter Zijlstra <peterz@infradead.org> - 2016-11-29 21:00 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 21:10 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-29 21:40 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Josh Poimboeuf <jpoimboe@redhat.com> - 2016-11-30 20:20 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-30 21:00 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Peter Zijlstra <peterz@infradead.org> - 2016-12-01 07:00 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-01 13:40 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Peter Zijlstra <peterz@infradead.org> - 2016-12-01 17:50 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-01 18:10 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Petr Mladek <pmladek@suse.com> - 2016-11-30 11:10 +0100
Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start Peter Zijlstra <peterz@infradead.org> - 2016-11-30 12:10 +0100
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