Re: [PATCH v3] sched/debug: Use sched_debug_lock to serialize use of cgroup_path[] only

2021-04-05 Thread Steven Rostedt
On Sun, 4 Apr 2021 21:27:00 -0400 Waiman Long wrote: > Thanks for the suggestion, but it also sound complicated. It's not that complicated. Similar tricks have been used elsewhere in the kernel. > > I think we can fix this lockup problem if we are willing to lose some It's not a lockup

Re: [PATCH v3] sched/debug: Use sched_debug_lock to serialize use of cgroup_path[] only

2021-04-04 Thread Waiman Long
On 4/4/21 9:27 PM, Waiman Long wrote: On 4/4/21 12:02 PM, Steven Rostedt wrote: On Fri, 2 Apr 2021 23:09:09 -0400 Waiman Long wrote: The main problem with sched_debug_lock is that under certain circumstances, a lock waiter may wait a long time to acquire the lock (in seconds). We can't

Re: [PATCH v3] sched/debug: Use sched_debug_lock to serialize use of cgroup_path[] only

2021-04-04 Thread Waiman Long
On 4/4/21 12:02 PM, Steven Rostedt wrote: On Fri, 2 Apr 2021 23:09:09 -0400 Waiman Long wrote: The main problem with sched_debug_lock is that under certain circumstances, a lock waiter may wait a long time to acquire the lock (in seconds). We can't insert touch_nmi_watchdog() while the cpu is

Re: [PATCH v3] sched/debug: Use sched_debug_lock to serialize use of cgroup_path[] only

2021-04-04 Thread Steven Rostedt
On Fri, 2 Apr 2021 23:09:09 -0400 Waiman Long wrote: > The main problem with sched_debug_lock is that under certain > circumstances, a lock waiter may wait a long time to acquire the lock > (in seconds). We can't insert touch_nmi_watchdog() while the cpu is > waiting for the spinlock. The

Re: [PATCH v3] sched/debug: Use sched_debug_lock to serialize use of cgroup_path[] only

2021-04-02 Thread Waiman Long
On 4/2/21 4:40 PM, Steven Rostedt wrote: On Thu, 1 Apr 2021 14:10:30 -0400 Waiman Long wrote: The handling of sysrq key can be activated by echoing the key to /proc/sysrq-trigger or via the magic key sequence typed into a terminal that is connected to the system in some way (serial, USB or

Re: [PATCH v3] sched/debug: Use sched_debug_lock to serialize use of cgroup_path[] only

2021-04-02 Thread Steven Rostedt
On Thu, 1 Apr 2021 14:10:30 -0400 Waiman Long wrote: > The handling of sysrq key can be activated by echoing the key to > /proc/sysrq-trigger or via the magic key sequence typed into a terminal > that is connected to the system in some way (serial, USB or other mean). > In the former case, the

[PATCH v3] sched/debug: Use sched_debug_lock to serialize use of cgroup_path[] only

2021-04-01 Thread Waiman Long
The handling of sysrq key can be activated by echoing the key to /proc/sysrq-trigger or via the magic key sequence typed into a terminal that is connected to the system in some way (serial, USB or other mean). In the former case, the handling is done in a user context. In the latter case, it is