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Date: Fri, 17 Jul 2026 21:56:42 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Jackie Liu <liu.yun@linux.dev>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] lib: cpu_rmap: reject zero-sized maps
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On Sat, 18 Jul 2026 12:21:55 +0800 Jackie Liu <liu.yun@linux.dev> wrote:

> From: Jackie Liu <liuyun01@kylinos.cn>
> 
> alloc_cpu_rmap() assigns an object index to each possible CPU using
> cpu % size. Passing zero therefore triggers a divide error instead of
> reporting that the map cannot be allocated.

Is there any situation in which this is known to trigger?

> Reject zero along with sizes that do not fit in the u16 map indices.

If passing zero is a caller bug then a divide-by-zero exception is a
fine way of reporting it.  So I'm not seeing a need to make any change
here.