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SubjectRe: [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages()
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On 1/14/20 3:32 AM, Michal Hocko wrote:
> On Tue 14-01-20 11:23:52, Vlastimil Babka wrote:
>> On 1/14/20 10:10 AM, Michal Hocko wrote:
>>> [Cc Ralph]
>>>> The reason is dump_page() does not print page->flags universally
>>>> and only does so for KSM, Anon and File pages while excluding
>>>> reserved pages at boot. Wondering should not we make printing
>>>> page->flags universal ?
>>>
>>> We used to do that and this caught me as a surprise when looking again.
>>> This is a result of 76a1850e4572 ("mm/debug.c: __dump_page() prints an
>>> extra line") which is a cleanup patch and I suspect this result was not
>>> anticipated.
>>>
>>> The following will do the trick but I cannot really say I like the code
>>> duplication. pr_cont in this case sounds like a much cleaner solution to
>>> me.
>>
>> How about this then?
>
> Yes makes sense as well.
>
>> diff --git mm/debug.c mm/debug.c
>> index 0461df1207cb..6a52316af839 100644
>> --- mm/debug.c
>> +++ mm/debug.c
>> @@ -47,6 +47,7 @@ void __dump_page(struct page *page, const char *reason)
>> struct address_space *mapping;
>> bool page_poisoned = PagePoisoned(page);
>> int mapcount;
>> + char *type = "";
>>
>> /*
>> * If struct page is poisoned don't access Page*() functions as that
>> @@ -78,9 +79,9 @@ void __dump_page(struct page *page, const char *reason)
>> page, page_ref_count(page), mapcount,
>> page->mapping, page_to_pgoff(page));
>> if (PageKsm(page))
>> - pr_warn("ksm flags: %#lx(%pGp)\n", page->flags, &page->flags);
>> + type = "ksm ";
>> else if (PageAnon(page))
>> - pr_warn("anon flags: %#lx(%pGp)\n", page->flags, &page->flags);
>> + type = "anon ";
>> else if (mapping) {
>> if (mapping->host && mapping->host->i_dentry.first) {
>> struct dentry *dentry;
>> @@ -88,10 +89,11 @@ void __dump_page(struct page *page, const char *reason)
>> pr_warn("%ps name:\"%pd\"\n", mapping->a_ops, dentry);
>> } else
>> pr_warn("%ps\n", mapping->a_ops);
>> - pr_warn("flags: %#lx(%pGp)\n", page->flags, &page->flags);
>> }
>> BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
>>
>> + pr_warn("%sflags: %#lx(%pGp)\n", type, page->flags, &page->flags);
>> +
>> hex_only:
>> print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
>> sizeof(unsigned long), page,
>>
>
Looks good to me. Thanks for the clean up.
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>

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