[Crash-utility] ps: issue with "waking" and "parked" task states?

[Dave Anderson]

----- Original Message -----
> Hi Dave,
> 
> I recently looked into a linux 4.0 dump where the "ps" command prints "??"
> for the state field of several tasks:
> 
> crash> ps
>     741    660   1      7b408000      ??   0.0    2152   2592  chcpu
>     748      2  24      20c284f00     IN   0.0       0      0  [migration/24]
>     752      2  22      20b1ccf00     ??   0.0       0      0  [migration/25]
> 
> Looking at the "task_struct->state" I get the following:
> 
>  crash> task_struct 7b408000 | grep state
>    state = 0x100,
>  crash> task_struct 20b1ccf00 | grep state
>    state = 0x200
> 
> Looking into include/linux/sched.h states are defined as follows:
> 
>  #define TASK_RUNNING            0
>  ...
>  #define TASK_WAKING             256
>  #define TASK_PARKED             512
> 
> When I issue "help -t" I get the following:
> 
>            RUNNING:   0 (0x0)
>      INTERRUPTIBLE:   1 (0x1)
>    UNINTERRUPTIBLE:   2 (0x2)
>            STOPPED:   4 (0x4)
>    TRACING_STOPPED:   8 (0x8)
>             ZOMBIE:  32 (0x20)
>               DEAD:  16 and 32 (0x10 and 0x20)
>           WAKEKILL:  64 (0x40)
>             WAKING: 128 (0x80)  <- Should be 256?
> 
> I have not digged deeper, but at least wanted to report this issue.
> Perhaps you see the problem at once.
> 
> Michael
> 
> 

I see it now.  The states are gathered from the kernel's task_state_array[].
So on a 3.9-based kernel, for example, it's this:

crash> p task_state_array
task_state_array = $1 = 
 {0xffffffff81a01959 "R (running)", 0xffffffff81a01965 "S (sleeping)", 0xffffffff81a01972 "D (disk sleep)", 0xffffffff81a01981 "T (stopped)", 0xffffffff81a0198d "t (tracing stop)", 0xffffffff81a0199e "Z (zombie)", 0xffffffff81a019a9 "X (dead)", 0xffffffff81a019b2 "x (dead)", 0xffffffff81a019bb "K (wakekill)", 0xffffffff81a019c8 "W (waking)", 0xffffffff81a019d3 "P (parked)"}
crash> 

And for example, here's the 3.10 kernel's declaration:

/*
 * The task state array is a strange "bitmap" of
 * reasons to sleep. Thus "running" is zero, and
 * you can test for combinations of others with
 * simple bit tests.
 */
static const char * const task_state_array[] = {
        "R (running)",          /*   0 */
        "S (sleeping)",         /*   1 */
        "D (disk sleep)",       /*   2 */
        "T (stopped)",          /*   4 */
        "t (tracing stop)",     /*   8 */
        "Z (zombie)",           /*  16 */
        "X (dead)",             /*  32 */
        "x (dead)",             /*  64 */
        "K (wakekill)",         /* 128 */
        "W (waking)",           /* 256 */
        "P (parked)",           /* 512 */
};

where on a 4.0.5 kernel, the wakekill, waking and parked fields no longer exist in the array:

crash> p task_state_array
task_state_array = $1 = 
 {0xffffffff81a73b42 "R (running)", 0xffffffff81a73b4e "S (sleeping)", 0xffffffff81a73b5b "D (disk sleep)", 0xffffffff81a73b6a "T (stopped)", 0xffffffff81a73b76 "t (tracing stop)", 0xffffffff81a73b87 "X (dead)", 0xffffffff81a73b90 "Z (zombie)"}
crash> 

This is the upstream kernel declaration:

static const char * const task_state_array[] = {
        "R (running)",          /*   0 */
        "S (sleeping)",         /*   1 */
        "D (disk sleep)",       /*   2 */
        "T (stopped)",          /*   4 */
        "t (tracing stop)",     /*   8 */
        "X (dead)",             /*  16 */
        "Z (zombie)",           /*  32 */
};

Not sure where the wakekill, waking, and parked went yet though...

Dave