On 8/16/23 7:53 AM, Jan Kara wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>
>
>
> On Tue 15-08-23 20:57:14, Bhatnagar, Rishabh wrote:
>> On 8/15/23 7:28 PM, Theodore Ts'o wrote:
>>> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>>>
>>>
>>>
>>> It would be helpful if you can translate address in the stack trace to
>>> line numbers. See [1] and the script in
>>> ./scripts/decode_stacktrace.sh in the kernel sources. (It is
>>> referenced in the web page at [1].)
>>>
>>> [1] https://docs.kernel.org/admin-guide/bug-hunting.html
>>>
>>> Of course, in order to interpret the line numbers, we'll need a
>>> pointer to the git repo of your kernel sources and the git commit ID
>>> you were using that presumably corresponds to 5.10.184-175.731.amzn2.x86_64.
>>>
>>> The stack trace for which I am particularly interested is the one for
>>> the jbd2/md0-8 task, e.g.:
>> Thanks for checking Ted.
>>
>> We don't have fast_commit feature enabled. So it should correspond to this
>> line:
>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/fs/jbd2/commit.c?h=linux-5.10.y#n496
>>
>>>> Not tainted 5.10.184-175.731.amzn2.x86_64 #1
>>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>>> task:jbd2/md0-8 state:D stack: 0 pid: 8068 ppid: 2
>>>> flags:0x00004080
>>>> Call Trace:
>>>> __schedule+0x1f9/0x660
>>>> schedule+0x46/0xb0
>>>> jbd2_journal_commit_transaction+0x35d/0x1880 [jbd2] <--------- line #?
>>>> ? update_load_avg+0x7a/0x5d0
>>>> ? add_wait_queue_exclusive+0x70/0x70
>>>> ? lock_timer_base+0x61/0x80
>>>> ? kjournald2+0xcf/0x360 [jbd2]
>>>> kjournald2+0xcf/0x360 [jbd2]
>>> Most of the other stack traces you refenced are tasks that are waiting
>>> for the transaction commit to complete so they can proceed with some
>>> file system operation. The stack traces which have
>>> start_this_handle() in them are examples of this going on. Stack
>>> traces of tasks that do *not* have start_this_handle() would be
>>> specially interesting.
>> I see all other stacks apart from kjournald have "start_this_handle".
> That would be strange. Can you post full output of "echo w
>> /proc/sysrq-trigger" to dmesg, ideally passed through scripts/faddr2line as
> Ted suggests. Thanks!
Sure i'll try to collect that. The system freezes when such a situation
happens and i'm not able
to collect much information. I'll try to crash the kernel and collect
kdump and see if i can get that info.
Can low available memory be a reason for a thread to not be able to
close the transaction handle for a long time?
Maybe some writeback thread starts the handle but is not able to
complete writeback?
>
> Honza
> --
> Jan Kara <[email protected]>
> SUSE Labs, CR