Re: Can RCU stall lead to hard lockups?

2018-02-06 Thread Paul E. McKenney
On Tue, Feb 06, 2018 at 08:55:04PM -0600, Serge E. Hallyn wrote: > On Tue, Feb 06, 2018 at 06:53:37PM -0800, Paul E. McKenney wrote: > > On Tue, Feb 06, 2018 at 08:33:03PM -0600, Serge E. Hallyn wrote: > > > On Sat, Feb 03, 2018 at 12:50:32PM -0800, Paul E. McKenney wrote: > > > > On Fri, Feb 02,

Re: Can RCU stall lead to hard lockups?

2018-02-06 Thread Paul E. McKenney
On Tue, Feb 06, 2018 at 08:55:04PM -0600, Serge E. Hallyn wrote: > On Tue, Feb 06, 2018 at 06:53:37PM -0800, Paul E. McKenney wrote: > > On Tue, Feb 06, 2018 at 08:33:03PM -0600, Serge E. Hallyn wrote: > > > On Sat, Feb 03, 2018 at 12:50:32PM -0800, Paul E. McKenney wrote: > > > > On Fri, Feb 02,

Re: Can RCU stall lead to hard lockups?

2018-02-06 Thread Serge E. Hallyn
On Tue, Feb 06, 2018 at 06:53:37PM -0800, Paul E. McKenney wrote: > On Tue, Feb 06, 2018 at 08:33:03PM -0600, Serge E. Hallyn wrote: > > On Sat, Feb 03, 2018 at 12:50:32PM -0800, Paul E. McKenney wrote: > > > On Fri, Feb 02, 2018 at 05:44:30PM -0600, Serge E. Hallyn wrote: > > > > Quoting Paul E.

Re: Can RCU stall lead to hard lockups?

2018-02-06 Thread Serge E. Hallyn
On Tue, Feb 06, 2018 at 06:53:37PM -0800, Paul E. McKenney wrote: > On Tue, Feb 06, 2018 at 08:33:03PM -0600, Serge E. Hallyn wrote: > > On Sat, Feb 03, 2018 at 12:50:32PM -0800, Paul E. McKenney wrote: > > > On Fri, Feb 02, 2018 at 05:44:30PM -0600, Serge E. Hallyn wrote: > > > > Quoting Paul E.

Re: Can RCU stall lead to hard lockups?

2018-02-06 Thread Paul E. McKenney
On Tue, Feb 06, 2018 at 08:33:03PM -0600, Serge E. Hallyn wrote: > On Sat, Feb 03, 2018 at 12:50:32PM -0800, Paul E. McKenney wrote: > > On Fri, Feb 02, 2018 at 05:44:30PM -0600, Serge E. Hallyn wrote: > > > Quoting Paul E. McKenney (paul...@linux.vnet.ibm.com): > > > > On Tue, Jan 09, 2018 at

Re: Can RCU stall lead to hard lockups?

2018-02-06 Thread Paul E. McKenney
On Tue, Feb 06, 2018 at 08:33:03PM -0600, Serge E. Hallyn wrote: > On Sat, Feb 03, 2018 at 12:50:32PM -0800, Paul E. McKenney wrote: > > On Fri, Feb 02, 2018 at 05:44:30PM -0600, Serge E. Hallyn wrote: > > > Quoting Paul E. McKenney (paul...@linux.vnet.ibm.com): > > > > On Tue, Jan 09, 2018 at

Re: Can RCU stall lead to hard lockups?

2018-02-06 Thread Serge E. Hallyn
On Sat, Feb 03, 2018 at 12:50:32PM -0800, Paul E. McKenney wrote: > On Fri, Feb 02, 2018 at 05:44:30PM -0600, Serge E. Hallyn wrote: > > Quoting Paul E. McKenney (paul...@linux.vnet.ibm.com): > > > On Tue, Jan 09, 2018 at 06:11:14AM -0800, Tejun Heo wrote: > > > > Hello, Paul. > > > > > > > > On

Re: Can RCU stall lead to hard lockups?

2018-02-06 Thread Serge E. Hallyn
On Sat, Feb 03, 2018 at 12:50:32PM -0800, Paul E. McKenney wrote: > On Fri, Feb 02, 2018 at 05:44:30PM -0600, Serge E. Hallyn wrote: > > Quoting Paul E. McKenney (paul...@linux.vnet.ibm.com): > > > On Tue, Jan 09, 2018 at 06:11:14AM -0800, Tejun Heo wrote: > > > > Hello, Paul. > > > > > > > > On

Re: Can RCU stall lead to hard lockups?

2018-02-03 Thread Paul E. McKenney
On Fri, Feb 02, 2018 at 05:44:30PM -0600, Serge E. Hallyn wrote: > Quoting Paul E. McKenney (paul...@linux.vnet.ibm.com): > > On Tue, Jan 09, 2018 at 06:11:14AM -0800, Tejun Heo wrote: > > > Hello, Paul. > > > > > > On Mon, Jan 08, 2018 at 08:24:25PM -0800, Paul E. McKenney wrote: > > > > > I

Re: Can RCU stall lead to hard lockups?

2018-02-03 Thread Paul E. McKenney
On Fri, Feb 02, 2018 at 05:44:30PM -0600, Serge E. Hallyn wrote: > Quoting Paul E. McKenney (paul...@linux.vnet.ibm.com): > > On Tue, Jan 09, 2018 at 06:11:14AM -0800, Tejun Heo wrote: > > > Hello, Paul. > > > > > > On Mon, Jan 08, 2018 at 08:24:25PM -0800, Paul E. McKenney wrote: > > > > > I

Re: Can RCU stall lead to hard lockups?

2018-02-02 Thread Serge E. Hallyn
Quoting Paul E. McKenney (paul...@linux.vnet.ibm.com): > On Tue, Jan 09, 2018 at 06:11:14AM -0800, Tejun Heo wrote: > > Hello, Paul. > > > > On Mon, Jan 08, 2018 at 08:24:25PM -0800, Paul E. McKenney wrote: > > > > I don't know the RCU code at all but it *looks* like the first CPU is > > > >

Re: Can RCU stall lead to hard lockups?

2018-02-02 Thread Serge E. Hallyn
Quoting Paul E. McKenney (paul...@linux.vnet.ibm.com): > On Tue, Jan 09, 2018 at 06:11:14AM -0800, Tejun Heo wrote: > > Hello, Paul. > > > > On Mon, Jan 08, 2018 at 08:24:25PM -0800, Paul E. McKenney wrote: > > > > I don't know the RCU code at all but it *looks* like the first CPU is > > > >

Re: Can RCU stall lead to hard lockups?

2018-01-09 Thread Paul E. McKenney
On Tue, Jan 09, 2018 at 06:11:14AM -0800, Tejun Heo wrote: > Hello, Paul. > > On Mon, Jan 08, 2018 at 08:24:25PM -0800, Paul E. McKenney wrote: > > > I don't know the RCU code at all but it *looks* like the first CPU is > > > taking a sweet while flushing printk buffer while holding a lock (the >

Re: Can RCU stall lead to hard lockups?

2018-01-09 Thread Paul E. McKenney
On Tue, Jan 09, 2018 at 06:11:14AM -0800, Tejun Heo wrote: > Hello, Paul. > > On Mon, Jan 08, 2018 at 08:24:25PM -0800, Paul E. McKenney wrote: > > > I don't know the RCU code at all but it *looks* like the first CPU is > > > taking a sweet while flushing printk buffer while holding a lock (the >

Re: Can RCU stall lead to hard lockups?

2018-01-09 Thread Tejun Heo
Hello, Paul. On Mon, Jan 08, 2018 at 08:24:25PM -0800, Paul E. McKenney wrote: > > I don't know the RCU code at all but it *looks* like the first CPU is > > taking a sweet while flushing printk buffer while holding a lock (the > > console is IPMI serial console, which faithfully emulates 115200

Re: Can RCU stall lead to hard lockups?

2018-01-09 Thread Tejun Heo
Hello, Paul. On Mon, Jan 08, 2018 at 08:24:25PM -0800, Paul E. McKenney wrote: > > I don't know the RCU code at all but it *looks* like the first CPU is > > taking a sweet while flushing printk buffer while holding a lock (the > > console is IPMI serial console, which faithfully emulates 115200

Re: Can RCU stall lead to hard lockups?

2018-01-08 Thread Paul E. McKenney
On Mon, Jan 08, 2018 at 07:52:07PM -0800, Tejun Heo wrote: > Hello, Paul. > > So, I was looking at a machine which triggered crashdump from NMI hard > lockup. The dmesg was filled up with backtraces - many were stuck in > reclaim path, which seems to be the culprit, the others were stuck in >

Re: Can RCU stall lead to hard lockups?

2018-01-08 Thread Paul E. McKenney
On Mon, Jan 08, 2018 at 07:52:07PM -0800, Tejun Heo wrote: > Hello, Paul. > > So, I was looking at a machine which triggered crashdump from NMI hard > lockup. The dmesg was filled up with backtraces - many were stuck in > reclaim path, which seems to be the culprit, the others were stuck in >