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SubjectRe: [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages()
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,
>

--
Michal Hocko
SUSE Labs

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