Re: [Crash-utility] [PATCH] Fix the "foreach DE" task identifier displays incorrect state tasks.
On 2023/07/31 17:18, lijiang wrote:
Thank you for the comments, Kazu.
On Mon, Jul 31, 2023 at 10:08 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com>
wrote:
> On 2023/07/28 20:15, Lianbo Jiang wrote:
>> Currently, the "foreach DE ps -m" command may display "DE" as
well as
>> "ZO" state tasks as below:
>>
>> crash> foreach DE ps -m
>> ...
>> [0 00:00:00.040] [ZO] PID: 11458 TASK: ffff91c75680d280 CPU: 7
> COMMAND: "ora_w01o_p01mci"
>> [0 00:00:00.044] [ZO] PID: 49118 TASK: ffff91c7bf3e8000 CPU: 19
> COMMAND: "oracle_49118_p0"
>> [0 00:00:00.050] [ZO] PID: 28748 TASK: ffff91a7cbde3180 CPU: 2
> COMMAND: "ora_imr0_p01sci"
>> [0 00:00:00.050] [DE] PID: 28405 TASK: ffff91a7c8eb0000 CPU: 27
> COMMAND: "ora_vktm_p01sci"
>> [0 00:00:00.051] [ZO] PID: 31716 TASK: ffff91a7f7192100 CPU: 6
> COMMAND: "ora_p001_p01sci"
>> ...
>
> Could you elaborate on why this happens?
>
>
When the "DE" identifier is specified in the foreach command, it needs to
skip the non-"DE" tasks. Currently, crash doesn't deal with this case,
only
handles some cases, such as "_RUNNING_", "_UNINTERRUPTIBLE_",
"_NOLOAD_",
etc. So most tasks will be displayed directly.
I'm concerned about the difference of the conditions between printing
> the "DE" state in task_state_string() and printing a "DE" task in
the
> foreach function in your patch:
>
> char *
> task_state_string(ulong task, char *buf, int verbose)
> {
> ...
> if ((state & _DEAD_) && !set) {
> sprintf(buf, "DE");
> valid++;
> set++;
> }
>
> On the other hand, the following means that "state == _DEAD_" is the
> "DE" state, not "state & _DEAD". So I'm wondering if
"foreach DE"
> command might drop some "DE" tasks with your patch?
>
>
The condition "state & _DEAD" can not filter out the tasks with a state
value of 0x50(0x10 + 0x40). It indicates that the "ZO" state tasks will be
always displayed, when the "DE" identifier is specified.
I just did the debug on it, let me share an example:
crash> foreach DE ps -m
...
foreach: state: 0x60, task_state: 0x50
[0 00:00:00.040] [ZO] PID: 11458 TASK: ffff91c75680d280 CPU: 7
COMMAND: "ora_w01o_p01mci"
foreach: state: 0x60, task_state: 0x50
[0 00:00:00.044] [ZO] PID: 49118 TASK: ffff91c7bf3e8000 CPU: 19
COMMAND: "oracle_49118_p0"
foreach: state: 0x60, task_state: 0x50
[0 00:00:00.050] [ZO] PID: 28748 TASK: ffff91a7cbde3180 CPU: 2
COMMAND: "ora_imr0_p01sci"
foreach: state: 0x60, task_state: 0x60
[0 00:00:00.050] [DE] PID: 28405 TASK: ffff91a7c8eb0000 CPU: 27
COMMAND: "ora_vktm_p01sci"
foreach: state: 0x60, task_state: 0x50
[0 00:00:00.051] [ZO] PID: 31716 TASK: ffff91a7f7192100 CPU: 6
COMMAND: "ora_p001_p01sci"
...
The DEAD state value is 0x60(0x20 + 0x40), the actual task state value is
0x50(0x10 + 0x40), and the ZOMBIE state value is 0x10, regardless of the
"task_state(task) & _DEAD_" or "task_state(task) & _ZOMBIE_",
the result is
always true. So the condition "state & _DEAD" can not handle this case.
OK, thanks for the explanation.
So the following condition cannot filter out the "ZO" tasks that have
EXIT_ZOMBIE(0x10) and TASK_DEAD(0x40) with _DEAD_(0x60).
} else if (!(task_state(tc->task) & fd->state))
continue;
What I was concerned about is that
+ if (task_state(tc->task) != _DEAD_)
+ continue;
this condition may skip "DE" tasks that have only either EXIT_DEAD(0x20)
or TASK_DEAD(0x40). If there can't be such tasks at any timing, then no
problem though.
Anyway, if you adopt that idea, my concern will be solved.
Thanks,
Kazu
And also the actual task has a "DE" state value of 0x60.
...
foreach: state: 0x60, task_state: 0x60
[0 00:00:00.050] [DE] PID: 28405 TASK: ffff91a7c8eb0000 CPU: 27
COMMAND: "ora_vktm_p01sci"
...
crash> help -t
...
RUNNING: 0 (0x0)
INTERRUPTIBLE: 1 (0x1)
UNINTERRUPTIBLE: 2 (0x2)
STOPPED: 4 (0x4)
TRACING_STOPPED: 8 (0x8)
ZOMBIE: 16 (0x10)
DEAD: 32 and 64 (0x20 and 0x40)
WAKEKILL: 128 (0x80)
WAKING: 256 (0x100)
PARKED: 512 (0x200)
crash>
Thanks.
Lianbo