linux-kernel - Re: [RFC PATCH] vmalloc: show more detail info in vmallocinfo for clarify

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Message-ID: <25eb2159-5398-856d-abcf-457cac84771b@huawei.com>
Date:   Wed, 31 May 2017 12:35:24 +0800
From:   Yisheng Xie <xieyisheng1@...wei.com>
To:     Tim Chen <tim.c.chen@...ux.intel.com>, <akpm@...ux-foundation.org>,
        <mhocko@...e.com>, <zijun_hu@....com>, <mingo@...nel.org>,
        <thgarnie@...gle.com>, <kirill.shutemov@...ux.intel.com>,
        <aryabinin@...tuozzo.com>, <chris@...is-wilson.co.uk>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <guohanjun@...wei.com>
Subject: Re: [RFC PATCH] vmalloc: show more detail info in vmallocinfo for
 clarify

Hi Tim,

Thanks for comment!
On 2017/5/31 8:56, Tim Chen wrote:
> On 05/19/2017 11:47 PM, Yisheng Xie wrote:
>> 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 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 freeing vm_area
>>  0xece7e000-0xece83000   20480 vm_map_ram
>>  0xf0099000-0xf00aa000   69632 vm_map_ram
>>  0xf1000000-0xf5001000 67112960 devm_ioremap+0x38/0x7c phys=40000000 ioremap
>> after apply this patch.
>>
>> Signed-off-by: Yisheng Xie <xieyisheng1@...wei.com>
>> ---
>>  mm/vmalloc.c | 10 +++++++++-
>>  1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
>> index b52aeed..dbb24fc 100644
>> --- a/mm/vmalloc.c
>> +++ b/mm/vmalloc.c
>> @@ -314,6 +314,7 @@ unsigned long vmalloc_to_pfn(const void *vmalloc_addr)
>>  
>>  /*** Global kva allocator ***/
>>  
>> +#define VM_LAZY_FREE	0x02
>>  #define VM_VM_AREA	0x04
>>  
>>  static DEFINE_SPINLOCK(vmap_area_lock);
>> @@ -1486,6 +1487,7 @@ struct vm_struct *remove_vm_area(const void *addr)
>>  		spin_lock(&vmap_area_lock);
>>  		va->vm = NULL;
>>  		va->flags &= ~VM_VM_AREA;
>> +		va->flags |= VM_LAZY_FREE;
>>  		spin_unlock(&vmap_area_lock);
>>  
>>  		vmap_debug_free_range(va->va_start, va->va_end);
>> @@ -2684,8 +2686,14 @@ static int s_show(struct seq_file *m, void *p)
>>  	 * s_show can encounter race with remove_vm_area, !VM_VM_AREA on
>>  	 * behalf of vmap area is being tear down or vm_map_ram allocation.
>>  	 */
>> -	if (!(va->flags & VM_VM_AREA))
>> +	if (!(va->flags & VM_VM_AREA)) {
>> +		seq_printf(m, "0x%pK-0x%pK %7ld %s\n",
>> +			(void *)va->va_start, (void *)va->va_end,
>> +			va->va_end - va->va_start,
>> +			va->flags & VM_LAZY_FREE ? "freeing vm_area" : "vm_map_ram");
> 
> Will be clearer to say "unpurged vm_area" instead of "freeing vm_area".

Yes, I will change it in next version.

Thanks
Yisheng Xie

> 
> Thanks.
> 
> Tim
> 
> .
>