linux-kernel - Re: [PATCH v1 5/5] mm/memory_hotplug: print only with DEBUG_VM in online/offline

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Date:   Mon, 20 Aug 2018 11:57:04 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Wei Yang <richard.weiyang@...il.com>,
        Oscar Salvador <osalvador@...hadventures.net>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Pavel Tatashin <pasha.tatashin@...cle.com>,
        Kemi Wang <kemi.wang@...el.com>,
        David Rientjes <rientjes@...gle.com>,
        Jia He <jia.he@...-semitech.com>,
        Oscar Salvador <osalvador@...e.de>,
        Petr Tesarik <ptesarik@...e.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Mathieu Malaterre <malat@...ian.org>,
        Baoquan He <bhe@...hat.com>, Ross Zwisler <zwisler@...nel.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH v1 5/5] mm/memory_hotplug: print only with DEBUG_VM in
 online/offline_pages()

On 19.08.2018 14:34, Wei Yang wrote:
> On Fri, Aug 17, 2018 at 10:18:53AM +0200, Oscar Salvador wrote:
>>>  failed_addition:
>>> +#ifdef CONFIG_DEBUG_VM
>>>  	pr_debug("online_pages [mem %#010llx-%#010llx] failed\n",
>>>  		 (unsigned long long) pfn << PAGE_SHIFT,
>>>  		 (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
>>> +#endif
>>
>> I have never been sure about this.
>> IMO, if I fail to online pages, I want to know I failed.
>> I think that pr_err would be better than pr_debug and without CONFIG_DEBUG_VM.
>>
>> But at least, if not, envolve it with a CONFIG_DEBUG_VM, but change pr_debug to pr_info.
>>
> 
> I don't have a clear rule about these debug macro neither.
> 
> While when you look at the page related logs in calculate_node_totalpages(),
> it is KERNEL_DEBUG level and without any config macro.
> 
> Maybe we should leave them at the same state?

I guess we can do that for the to debug messages.

When offlining memory right now:

:/# echo 0 > /sys/devices/system/memory/memory9/online
[   24.476207] Offlined Pages 32768
[   24.477200] remove from free list 48000 1024 50000
[   24.477896] remove from free list 48400 1024 50000
[   24.478584] remove from free list 48800 1024 50000
[   24.479454] remove from free list 48c00 1024 50000
[   24.480192] remove from free list 49000 1024 50000
[   24.480957] remove from free list 49400 1024 50000
[   24.481752] remove from free list 49800 1024 50000
[   24.482578] remove from free list 49c00 1024 50000
[   24.483302] remove from free list 4a000 1024 50000
[   24.484300] remove from free list 4a400 1024 50000
[   24.484902] remove from free list 4a800 1024 50000
[   24.485462] remove from free list 4ac00 1024 50000
[   24.486381] remove from free list 4b000 1024 50000
[   24.487108] remove from free list 4b400 1024 50000
[   24.487842] remove from free list 4b800 1024 50000
[   24.488610] remove from free list 4bc00 1024 50000
[   24.489548] remove from free list 4c000 1024 50000
[   24.490392] remove from free list 4c400 1024 50000
[   24.491224] remove from free list 4c800 1024 50000
...

While "remove from free list" is pr_info under CONFIG_DEBUG_VM,
"Offlined Pages ..." is pr_info without CONFIG_DEBUG_VM.

-- 

Thanks,

David / dhildenb