Messages in this thread | | | Date | Wed, 13 Mar 2024 10:28:41 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v2 0/4] perf: Make SIGTRAP and __perf_pending_irq() work on RT. |
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On Wed, Mar 13, 2024 at 09:13:03AM +0100, Sebastian Andrzej Siewior wrote: > On 2024-03-12 18:42:38 [-0300], Arnaldo Carvalho de Melo wrote: > … > > But: > > > > [acme@nine ~]$ pidof exec_child > > 24273 24271 24270 24269 24268 24267 24266 24265 24264 24263 24262 24261 24260 24259 > … > > > [root@nine ~]# cat /proc/24263/stack > > [<0>] irqentry_exit_to_user_mode+0x1c9/0x1e0 > > [<0>] asm_sysvec_apic_timer_interrupt+0x16/0x20 > > [root@nine ~]# > … > > [acme@nine ~]$ ps ax|grep exec_child| wc -l > > 504 > > [acme@nine ~]$ ps ax|grep exec_child| tail > > 24264 pts/0 R 0:04 exec_child > > 24265 pts/0 R 0:04 exec_child > > 24266 pts/0 R 0:04 exec_child > > 24267 pts/0 R 0:04 exec_child > > 24268 pts/0 R 0:04 exec_child > > 24269 pts/0 R 0:04 exec_child > > 24270 pts/0 R 0:04 exec_child > > 24271 pts/0 R 0:04 exec_child > > 24273 pts/0 R 0:04 exec_child > > 26704 pts/1 S+ 0:00 grep --color=auto exec_child > > [acme@nine ~]$ > > > > All in 'R' state. > > > > [root@nine ~]# killall exec_child > > exec_child: no process found > > [root@nine ~]# ps ax | grep exec_child | head -5 > > 22964 pts/0 R 0:06 exec_child > > 23046 pts/0 R 0:05 exec_child > > 23128 pts/0 R 0:05 exec_child > > 23129 pts/0 R 0:05 exec_child > > 23181 pts/0 R 0:05 exec_child > > [root@nine ~]# kill 22964 23046 23128 23129 23181 > > [root@nine ~]# ps ax | grep exec_child | head -5 > > 23182 pts/0 R 0:06 exec_child > > 23196 pts/0 R 0:06 exec_child > > 23197 pts/0 R 0:06 exec_child > > 23210 pts/0 R 0:06 exec_child > > 23213 pts/0 R 0:06 exec_child > > [root@nine ~]#
> You can't kill them?
I can, they remain in R state and I can kill them with 'kill `pidof exec_child`'
> > at the end they disappeared, on this last run.
> > But if I do a 'killall remove_on_exec' and stop that loop (control+C/Z) > > we get all those exec_child running a seemingly eternal loop: > > Is this new or was it there? Is this VM or bare metal?
bare metal.
> One part I don't get: did you let it run or did you kill it?
If I let them run they will finish and exit, no exec_child remains.
If I instead try to stop the loop that goes on forking the 100 of them, then the exec_child remain spinning.
> `exec_child' spins until a signal is received or the parent kills it. So
> it shouldn't remain there for ever. And my guess, that it is in spinning > in userland and not in kernel.
Checking that now, the stack is the one I posted:
> > [root@nine ~]# cat /proc/24263/stack > > [<0>] irqentry_exit_to_user_mode+0x1c9/0x1e0 > > [<0>] asm_sysvec_apic_timer_interrupt+0x16/0x20 > > [root@nine ~]#
> I tried it on bare metal and VM and couldn't reproduce this.
All my tests are in bare metal.
- Arnaldo
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