linux-kernel - Re: Query: Crash is coming during /prod/PID/stat and do

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Date:   Tue, 16 Jan 2018 11:06:47 +0530
From:   "Kohli, Gaurav" <gkohli@...eaurora.org>
To:     Alexey Dobriyan <adobriyan@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: Query: Crash is coming during /prod/PID/stat and do_exit of same
 task

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 = {

     counter = 0x4

   }

struct task_struct.flags -x 0xFFFFFFE80D8C2280

   flags = 0x40870c

crash_64> struct task_struct.exit_code -x 0xFFFFFFE80D8C2280

   exit_code = 0x6

  struct task_struct.state -x 0xFFFFFFE80D8C2280

   state = 0x40
  

Please find below crash stack:

-000|user_stack_pointer(inline)

-000|do_task_stat(

     |    m = 0xFFFFFFE7A5CD7380,

     |    ns = 0xFFFFFF8E7C43C748,

     |  ?,

     |    task = 0xFFFFFFE80D8C2280,

     |  ?)

     |  tty_pgrp = 0

     |  ppid = 2084696064

     |  sid = 0

     |  mm = 0xFFFFFFE7B4424140

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

     |  flags = 18446743969119403392

-001|proc_tgid_stat(

     |    m = 0xFFFFFFE7A5CD7380,

     |  ?,

     |  ?,

     |  ?)

-002|atomic_sub_return(inline)

Regards
Gaurav

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