linux-kernel - Re: [PATCH] mm: fix printk format within cma

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Message-ID: <ZD4QsGd0DwHa83K1@casper.infradead.org>
Date:   Tue, 18 Apr 2023 04:38:24 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     "zhaoyang.huang" <zhaoyang.huang@...soc.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Minchan Kim <minchan@...nel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Zhaoyang Huang <huangzhaoyang@...il.com>, ke.wang@...soc.com
Subject: Re: [PATCH] mm: fix printk format within cma

On Tue, Apr 18, 2023 at 11:33:09AM +0800, zhaoyang.huang wrote:
> cma and page pointer printed via %p are hash value which make debug to be hard.
> change them to %px.

Why does printing the page pointer make any sense at all?  Surely the
PFN makes much more sense.

> [63321.482751] [c7] cma: cma_alloc(): memory range at 000000000b5e462c is busy, retrying
> [63321.482786] [c7] cma: cma_alloc(): memory range at 000000000f7d6fae is busy, retrying
> [63321.482823] [c7] cma: cma_alloc(): memory range at 00000000e653b59b is busy, retrying
> [63322.378890] [c7] cma: cma_release(page 00000000dd53cf48)
> [63322.378913] [c7] cma: cma_release(page 00000000315f703d)
> [63322.378925] [c7] cma: cma_release(page 00000000791e3a5f)
> 
> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@...soc.com>
> ---
>  mm/cma.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/cma.c b/mm/cma.c
> index 4a978e0..dfe9813 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -435,7 +435,7 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
>  	if (!cma || !cma->count || !cma->bitmap)
>  		goto out;
>  
> -	pr_debug("%s(cma %p, count %lu, align %d)\n", __func__, (void *)cma,
> +	pr_debug("%s(cma %px, count %lu, align %d)\n", __func__, (void *)cma,
>  		 count, align);
>  
>  	if (!count)
> @@ -534,7 +534,7 @@ bool cma_pages_valid(struct cma *cma, const struct page *pages,
>  	pfn = page_to_pfn(pages);
>  
>  	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) {
> -		pr_debug("%s(page %p, count %lu)\n", __func__,
> +		pr_debug("%s(page %px, count %lu)\n", __func__,
>  						(void *)pages, count);
>  		return false;
>  	}
> @@ -560,7 +560,7 @@ bool cma_release(struct cma *cma, const struct page *pages,
>  	if (!cma_pages_valid(cma, pages, count))
>  		return false;
>  
> -	pr_debug("%s(page %p, count %lu)\n", __func__, (void *)pages, count);
> +	pr_debug("%s(page %px, count %lu)\n", __func__, (void *)pages, count);
>  
>  	pfn = page_to_pfn(pages);
>  
> -- 
> 1.9.1
> 
>