linux-kernel - Re: [PATCH] mm/debug:

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Date:   Mon, 11 Nov 2019 15:02:11 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Ralph Campbell <rcampbell@...dia.com>
Cc:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/debug:

On Mon, 11 Nov 2019 14:49:35 -0800 Ralph Campbell <rcampbell@...dia.com> wrote:

> When dumping struct page information, __dump_page() prints the page type
> with a trailing blank followed by the page flags on a separate line:
> 
> anon
> flags: 0x100000000090034(uptodate|lru|active|head|swapbacked)
> 
> Fix this by using pr_cont() instead of pr_warn() to get a single line:
> 
> anon flags: 0x100000000090034(uptodate|lru|active|head|swapbacked)
> 
> Signed-off-by: Ralph Campbell <rcampbell@...dia.com>
> ---
>  mm/debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/debug.c b/mm/debug.c
> index 8345bb6e4769..752c78721ea0 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -87,7 +87,7 @@ void __dump_page(struct page *page, const char *reason)
>  	}
>  	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
>  
> -	pr_warn("flags: %#lx(%pGp)\n", page->flags, &page->flags);
> +	pr_cont("flags: %#lx(%pGp)\n", page->flags, &page->flags);
>  
>  hex_only:
>  	print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,

This is the case if PageAnon || PageKsm || mapping.  If it is, say,
PageSlab then we effectively do

	pr_warn("stuff-with-no-newline");
	pr_cont("\n");
	pr_cont("flags: ...\n");

does this work OK?  what facility level will that "flags: " line get?