linux-kernel - Re: [PATCH] mm: change size_t to unsigned int for cma

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Date:   Mon, 29 Mar 2021 13:12:33 -0700
From:   Minchan Kim <minchan@...nel.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, david@...hat.com
Subject: Re: [PATCH] mm: change size_t to unsigned int for cma_alloc

On Mon, Mar 29, 2021 at 07:44:31PM +0100, Matthew Wilcox wrote:
> On Mon, Mar 29, 2021 at 11:25:53AM -0700, Minchan Kim wrote:
> > size_t in cma_alloc is confusing since it makes people think
> > it's byte count, not pages. Fix it.
> 
> i think it has to be unsigned long.
> 
> 67a2e213e7e937c41c52ab5bc46bf3f4de469f6e

Thanks for the pinter. I wanted to have the smallest change.
The commit leads me to change cma_release, trace_cma_alloc,
cma_clear_bitmap and front_contig_range as well.(Not sure
we have more. Will check).

Ccing david@...hat.com for upcoming changing free_contig_range.

> 
> > Link: https://lore.kernel.org/linux-mm/20210324043434.GP1719932@casper.infradead.org/
> > Cc: Matthew Wilcox <willy@...radead.org>
> > Signed-off-by: Minchan Kim <minchan@...nel.org>
> > ---
> >  include/linux/cma.h | 2 +-
> >  mm/cma.c            | 8 ++++----
> >  2 files changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/include/linux/cma.h b/include/linux/cma.h
> > index 217999c8a762..a873edc20ca2 100644
> > --- a/include/linux/cma.h
> > +++ b/include/linux/cma.h
> > @@ -44,7 +44,7 @@ extern int cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
> >  					unsigned int order_per_bit,
> >  					const char *name,
> >  					struct cma **res_cma);
> > -extern struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
> > +extern struct page *cma_alloc(struct cma *cma, unsigned int count, unsigned int align,
> >  			      bool no_warn);
> >  extern bool cma_release(struct cma *cma, const struct page *pages, unsigned int count);
> >  
> > diff --git a/mm/cma.c b/mm/cma.c
> > index 08c45157911a..24dc01e26d45 100644
> > --- a/mm/cma.c
> > +++ b/mm/cma.c
> > @@ -423,21 +423,21 @@ static inline void cma_debug_show_areas(struct cma *cma) { }
> >   * This function allocates part of contiguous memory on specific
> >   * contiguous memory area.
> >   */
> > -struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
> > +struct page *cma_alloc(struct cma *cma, unsigned int count, unsigned int align,
> >  		       bool no_warn)
> >  {
> >  	unsigned long mask, offset;
> >  	unsigned long pfn = -1;
> >  	unsigned long start = 0;
> >  	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
> > -	size_t i;
> > +	unsigned int i;
> >  	struct page *page = NULL;
> >  	int ret = -ENOMEM;
> >  
> >  	if (!cma || !cma->count || !cma->bitmap)
> >  		goto out;
> >  
> > -	pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
> > +	pr_debug("%s(cma %p, count %u, align %d)\n", __func__, (void *)cma,
> >  		 count, align);
> >  
> >  	if (!count)
> > @@ -500,7 +500,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
> >  	}
> >  
> >  	if (ret && !no_warn) {
> > -		pr_err_ratelimited("%s: %s: alloc failed, req-size: %zu pages, ret: %d\n",
> > +		pr_err_ratelimited("%s: %s: alloc failed, req-size: %u pages, ret: %d\n",
> >  				   __func__, cma->name, count, ret);
> >  		cma_debug_show_areas(cma);
> >  	}
> > -- 
> > 2.31.0.291.g576ba9dcdaf-goog
> > 
> >