On 2022/09/01 17:15, Tao Liu wrote:
>>> When kernel enabled CONFIG_VMAP_STACK, stack can be allocated to
>>> vmalloced area. Currently crash didn't handle the case, as a result,
>>> kmem will not print the task context as expected. This patch fix the
>>> bug by checking if the address is a vmalloced stack first.
>>>
>>> Before:
>>> crash> kmem ffffb7efce9bbe28
>>> VMAP_AREA VM_STRUCT ADDRESS RANGE SIZE
>>> ffff94eb9102c640 ffff94eb9102b140 ffffb7efce9b8000 - ffffb7efce9bd000 20480
>>>
>>> PAGE PHYSICAL MAPPING INDEX CNT FLAGS
>>> ffffdd28220dc000 1883700000 0 0 1 50000000000000
>>>
>>> After:
>>> crash> kmem ffffb7efce9bbe28
>>> PID: 847
>>> COMMAND: "khungtaskd"
>>> TASK: ffff94f8038f4000 [THREAD_INFO: ffff94f8038f4000]
>>> CPU: 72
>>> STATE: TASK_RUNNING (PANIC)
>>>
>>> VMAP_AREA VM_STRUCT ADDRESS RANGE SIZE
>>> ffff94eb9102c640 ffff94eb9102b140 ffffb7efce9b8000 - ffffb7efce9bd000 20480
>>>
>>
>> I have one question: If the given physical address falls in the vmalloc area, it won't print the task context, is that expected? For example:
>>
>
> Thanks for pointing it out. Hmm... I didn't consider the physical
> address case as vtop does. I will improve the patch and send v3.
For physical address, a context is not shown also without CONFIG_VMAP_STACK.
crash> kmem ffff9288bc977f00
PID: 1
COMMAND: "systemd"
TASK: ffff9288bc978000 [THREAD_INFO: ffff9288bc974000]
CPU: 10
STATE: TASK_INTERRUPTIBLE
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
ffffd91fc1f25dc0 7c977000 0 0 0 1fffff00000000
crash> kmem 7c977f00
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
ffffd91fc1f25dc0 7c977000 0 0 0 1fffff00000000
Some information for virtual address is not shown with physical address,
it's kind of expected. And we have the ptov command, personally I don't
think it needs to do.
but if you change this behavior, it might be good in a separate patch.
Thanks,
Kazu
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