linux-kernel - Re: [PATCH] mm/cma: print total and used pages in cma

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Message-Id: <20250815234528.882ab58247cefc96e4137811@linux-foundation.org>
Date: Fri, 15 Aug 2025 23:45:28 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: David Hildenbrand <david@...hat.com>
Cc: Xiang Gao <gxxa03070307@...il.com>, lorenzo.stoakes@...cle.com,
 Liam.Howlett@...cle.com, vbabka@...e.cz, rppt@...nel.org,
 surenb@...gle.com, mhocko@...e.com, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, gaoxiang17 <gaoxiang17@...omi.com>
Subject: Re: [PATCH] mm/cma: print total and used pages in cma_alloc()

On Sat, 16 Aug 2025 08:27:39 +0200 David Hildenbrand <david@...hat.com> wrote:

> > @@ -858,8 +869,8 @@ static struct page *__cma_alloc(struct cma *cma, unsigned long count,
> >   	if (!cma || !cma->count)
> >   		return page;
> >   
> > -	pr_debug("%s(cma %p, name: %s, count %lu, align %d)\n", __func__,
> > -		(void *)cma, cma->name, count, align);
> > +	pr_debug("%s(cma %p, name: %s, total pages: %lu, used pages: %lu, request pages: %lu, align %d)\n",
> > +		__func__, (void *)cma, cma->name, cma->count, cma_get_used_pages(cma), count, align);
> 
> 		^ one space missing for proper indentation.
> 
> But doing another spinlock cycle just for debugging purposes? That does 
> not feel right, sorry.

If we're calling pr_debug() frequently enough for this to matter, we
have other problems!