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Subject: Re: [PATCH v2] mm: page_alloc: dump migrate-failed pages
To:     Minchan Kim <minchan@kernel.org>, Michal Hocko <mhocko@suse.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        John Dias <joaodias@google.com>,
        Jason Baron <jbaron@akamai.com>
References: <20210308202047.1903802-1-minchan@kernel.org>
 <YEdAw6gnp9XxoWUQ@dhcp22.suse.cz> <YEefLYiX6rF3Uk4E@google.com>
 <YEh4doXvyuRl5BDB@google.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
Message-ID: <5f0e17f2-b161-f0f1-65a4-a7b3af4d2cce@redhat.com>
Date:   Wed, 10 Mar 2021 09:20:40 +0100
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On 10.03.21 08:42, Minchan Kim wrote:
> On Tue, Mar 09, 2021 at 08:15:41AM -0800, Minchan Kim wrote:
> 
> < snip >
> 
>>> [...]
>>>> +void dump_migrate_failure_pages(struct list_head *page_list)
>>>> +{
>>>> +	DEFINE_DYNAMIC_DEBUG_METADATA(descriptor,
>>>> +			"migrate failure");
>>>> +	if (DYNAMIC_DEBUG_BRANCH(descriptor) &&
>>>> +			alloc_contig_ratelimit()) {
>>>> +		struct page *page;
>>>> +
>>>> +		WARN(1, "failed callstack");
>>>> +		list_for_each_entry(page, page_list, lru)
>>>> +			dump_page(page, "migration failure");
>>>> +	}
>>>
>>> Apart from the above, do we have to warn for something that is a
>>> debugging aid? A similar concern wrt dump_page which uses pr_warn and
>>
>> Make sense.
>>
>>> page owner is using even pr_alert.
>>> Would it make sense to add a loglevel parameter both into __dump_page
>>> and dump_page_owner?
>>
>> Let me try it.
> 
> I looked though them and made first draft to clean them up.
> 
> It's bigger than my initial expectaion because there are many callsites
> to use dump_page and stack_trace_print inconsistent loglevel.
> Since it's not a specific problem for this work, I'd like to deal with
> it as separate patchset since I don't want to be stuck on here for my
> initial goal.

Why the need to rush regarding your series?

If it will clean up your patch significantly, then I think doing the 
cleanups first is the proper way to go.

I really don't get why this is a real problem.


-- 
Thanks,

David / dhildenb