Messages in this thread | | | Date | Thu, 28 May 2020 13:48:39 -0700 | From | "Paul E. McKenney" <> | Subject | Re: WARNING: suspicious RCU usage in idtentry_exit |
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On Thu, May 28, 2020 at 10:19:02PM +0200, Thomas Gleixner wrote: > Paul, > > "Paul E. McKenney" <paulmck@kernel.org> writes: > > On Thu, May 28, 2020 at 03:33:44PM +0200, Thomas Gleixner wrote: > >> syzbot <syzbot+3ae5eaae0809ee311e75@syzkaller.appspotmail.com> writes: > >> Weird. I have no idea how that thing is an EQS here. > > > > No argument on the "Weird" part! ;-) > > > > Is this a NO_HZ_FULL=y kernel? > > No, it has only NO_HZ_IDLE. > > https://syzkaller.appspot.com/x/.config?x=47b0740d89299c10
OK, from the .config, another suggestion is to build the kernel with CONFIG_RCU_EQS_DEBUG=y. This still requires that this issue be reproduced, but it might catch the problem earlier.
> > If so, one possibility is that the call > > to rcu_user_exit() went missing somehow. If not, then RCU should have > > been watching userspace execution. > > > > Again, the only thing I can think of (should this prove to be > > reproducible) is the rcu_dyntick trace event. > > :) > > Thanks, > > tglx
Thanx, Paul
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