Messages in this thread |  | | From | "Kohli, Gaurav" <> | Subject | Query: Crash is coming during /prod/PID/stat and do_exit of same task | Date | Tue, 9 Jan 2018 19:03:05 +0530 |
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HI ,
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:
Below is the crash trace: 49750.534377] Kernel BUG at ffffff8e7a4c53a8 [verbose debug info unavailable] [49750.534394] task: ffffffe7b4475580 task.stack: ffffffe7a5f0c000 [49750.534400] PC is at do_task_stat+0x740/0x908 [49750.534402] LR is at do_task_stat+0xa4/0x908 [49750.534403] pc : [<ffffff8e7a4c53a8>] lr : [<ffffff8e7a4c4d0c>] pstate: 80400145 [49750.534404] sp : ffffffe7a5f0fbd0
and here is stack trace on that core:
-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, | ?,
Below are task stats which shows , process completed the do_exit call: 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
In our build both patches are there , fs/proc: report eip/esp in /prod/PID/stat for coredumping
and also task.state has already set PF_DUMPCORE as it got the sigabrt signal.
Regards Gaurav
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