Re: [Qustion] vmalloc area overlap with another allocated vmalloc area

[zhong jiang]

On 2017/5/17 21:44, Michal Hocko wrote:
> On Wed 17-05-17 20:53:57, zhong jiang wrote:
>> +to linux-mm maintainer for any suggestions
>>
>> Thanks
>> zhongjiang
>> On 2017/5/16 13:03, zhong jiang wrote:
>>> Hi
>>>
>>> I  hit the following issue by runing /proc/vmallocinfo.  The kernel is 4.1 stable and
>>> 32 bit to be used.  after I expand the vamlloc area,  the issue is not occur again.
>>> it is related to the overflow. but I do not see any problem so far.
> Is this a clean 4.1 stable kernel without any additional patches on top?
> Are you able to reproduce this? How? Does the same problem happen with
> the current Linus tree?
  It is hard to reproduce.  just for special case and only once. we can not structure the case.
  I do not test it in Linus tree so far.  because I know it is hard to reprodeuce.

  Just by reading the code, I do not find the same issue. so I have no idea.

 Thanks
 zhongjiang 
>>> cat /proc/vmallocinfo
>>> 0xf1580000-0xf1600000  524288 raw_dump_mem_write+0x10c/0x188 phys=8b901000 ioremap
>>> 0xf1638000-0xf163a000    8192 mcss_pou_queue_init+0xa0/0x13c [mcss] phys=fc614000 ioremap
>>> 0xf528e000-0xf5292000   16384 n_tty_open+0x10/0xd0 pages=3 vmalloc
>>> 0xf5000000-0xf9001000 67112960 devm_ioremap+0x38/0x70 phys=40000000 ioremap
>>> 0xfe001000-0xfe002000    4096 iotable_init+0x0/0xc phys=20001000 ioremap
>>> 0xfe200000-0xfe201000    4096 iotable_init+0x0/0xc phys=1a000000 ioremap
>>> 0xff100000-0xff101000    4096 iotable_init+0x0/0xc phys=2000a000 ioremap
>>>
>>> n_tty_open allocate the vmap area is surrounded by the devm_ioremap ioremap by above info.
>>> I do not see also the race in the condition.
>>>
>>> I have no idea to the issue.  Anyone has any suggestions will be appreicated.
>>> The related config is attatched.
>>>
>>> Thanks
>>> zhongjiang