From: Minchan Kim <minchan@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: change size_t to unsigned int for cma_alloc
Date: Tue, 30 Mar 2021 08:00:13 -0700 [thread overview]
Message-ID: <YGM8/V7iv3j6JWyx@google.com> (raw)
In-Reply-To: <6d305211-c956-ad80-5908-703d07fca441@redhat.com>
On Tue, Mar 30, 2021 at 09:58:37AM +0200, David Hildenbrand wrote:
> On 29.03.21 22:12, Minchan Kim wrote:
> > 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
>
> Right.
>
> Fortunately, we don't have such large allocations yet via
> CMA/alloc_contig_range
>
> >
> > 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@redhat.com for upcoming changing free_contig_range.
>
> While at it, we might want to convert free_contig_range() to eat
> "unsigned long start, unsigned long end" like alloc_contig_range(), instead
> of "unsigned long pfn, unsigned int nr_pages" like alloc_contig_pages() ...
Well, I personllay tempted to change alloc_contig_range, not
free_contig_range because base_pfn with nr_pages was more
straightforward than base_pfn and end_pfn in that we don't
need to tell whether end_pfn is inclusive or exclusive.
When I look at callers of [alloc|free]_contig_range, many of them
already have used nr_pages based approach rather than start_pfn,
end_pfn. If your suggestion come from that "it's *range* API",
I'd like to rename it with "alloc_contig_pages|free_contig_pages".
Since it's beyond the goal of this patch and might be controversial,
I will not deal with it in this patch.
next prev parent reply other threads:[~2021-03-30 15:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-29 18:25 [PATCH] mm: change size_t to unsigned int for cma_alloc Minchan Kim
2021-03-29 18:44 ` Matthew Wilcox
2021-03-29 20:12 ` Minchan Kim
2021-03-30 7:58 ` David Hildenbrand
2021-03-30 15:00 ` Minchan Kim [this message]
2021-03-30 15:05 ` David Hildenbrand
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