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SubjectRe: [PATCH v2] vmalloc: show more detail info in vmallocinfo for clarify
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Hi Michael,

Thanks for comment!
On 2017/8/1 19:00, Michael Ellerman wrote:
> Yisheng Xie <xieyisheng1@huawei.com> writes:
>
>> When ioremap a 67112960 bytes vm_area with the vmallocinfo:
>> [..]
>> 0xec79b000-0xec7fa000 389120 ftl_add_mtd+0x4d0/0x754 pages=94 vmalloc
>> 0xec800000-0xecbe1000 4067328 kbox_proc_mem_write+0x104/0x1c4 phys=8b520000 ioremap
>>
>> we get the result:
>> 0xf1000000-0xf5001000 67112960 devm_ioremap+0x38/0x7c phys=40000000 ioremap
>>
>> For the align for ioremap must be less than '1 << IOREMAP_MAX_ORDER':
>> if (flags & VM_IOREMAP)
>> align = 1ul << clamp_t(int, get_count_order_long(size),
>> PAGE_SHIFT, IOREMAP_MAX_ORDER);
>>
>> So it makes idiot like me a litter puzzle why jump the vm_area from
>> 0xec800000-0xecbe1000 to 0xf1000000-0xf5001000, and leave
>> 0xed000000-0xf1000000 as a big hole.
>>
>> This is to show all of vm_area, including which is freeing but still in
>> vmap_area_list, to make it more clear about why we will get
>> 0xf1000000-0xf5001000 int the above case. And we will get the
>> vmallocinfo like:
>> [..]
>> 0xec79b000-0xec7fa000 389120 ftl_add_mtd+0x4d0/0x754 pages=94 vmalloc
>> 0xec800000-0xecbe1000 4067328 kbox_proc_mem_write+0x104/0x1c4 phys=8b520000 ioremap
>> [..]
>> 0xece7c000-0xece7e000 8192 unpurged vm_area
>> 0xece7e000-0xece83000 20480 vm_map_ram
>> 0xf0099000-0xf00aa000 69632 vm_map_ram
>
> My vmallocinfo is full of these unpurged areas, should I be worried?

The unpurged areas is a lazy free vm area, which maybe free at anytime. e.g. if the
nr_lazy(count in pages) is bigger than lazy_max_pages(), these area will be purged
and free.

So I think you do not have worried about it.

Thanks
Yisheng Xie

>
> # grep -c "unpurged" /proc/vmallocinfo
> 311
>
> cheers
>
> .
>

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