Re: Query: Crash is coming during /prod/PID/stat and do_exit of same task

[Kohli, Gaurav]

On 1/10/2018 10:50 AM, Alexey Dobriyan wrote:

> > We are seeing crash in do_task_stat while accessing stack pointer, It
> > seems same task has already completed do_exit call.
> > So it seems a race between them:
> Please, post exact kernel version and struct task_struct::usage if you
> still have that kernel core (or even full task_struct)

Hi Alexey,

We are working on 4.9.65 and Please find below usage value and other task_struct value,
please let me know if some other data required as well.

crash_64> struct task_struct.usage -x 0xFFFFFFE80D8C2280

 usage = {

ÂÂÂ counter = 0x4

 }

struct task_struct.flags -x 0xFFFFFFE80D8C2280

 flags = 0x40870c

crash_64> struct task_struct.exit_code -x 0xFFFFFFE80D8C2280

 exit_code = 0x6

Âstruct task_struct.state -x 0xFFFFFFE80D8C2280

 state = 0x40
 

Please find below crash stack:

-000|user_stack_pointer(inline)

-000|do_task_stat(

ÂÂÂ |ÂÂÂ m = 0xFFFFFFE7A5CD7380,

ÂÂÂ |ÂÂÂ ns = 0xFFFFFF8E7C43C748,

ÂÂÂ |Â ?,

ÂÂÂ |ÂÂÂ task = 0xFFFFFFE80D8C2280,

ÂÂÂ |Â ?)

ÂÂÂ |Â tty_pgrp = 0

ÂÂÂ |Â ppid = 2084696064

ÂÂÂ |Â sid = 0

ÂÂÂ |Â mm = 0xFFFFFFE7B4424140

ÂÂÂ |Â tcomm = (84, 9, 71, 122, 142, 255, 255, 255, 48, 253, 240, 165, 231, 255, 255, 255)

ÂÂÂ |Â flags = 18446743969119403392

-001|proc_tgid_stat(

ÂÂÂ |ÂÂÂ m = 0xFFFFFFE7A5CD7380,

ÂÂÂ |Â ?,

ÂÂÂ |Â ?,

ÂÂÂ |Â ?)

-002|atomic_sub_return(inline)

Regards
Gaurav

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