linux-kernel - Re: [RFC PATCH 1/1] mm/percpu.c: fix memory leakage issue when allocate a odd alignment area

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Message-ID: <20161011172228.GA30403@dhcp22.suse.cz>
Date:   Tue, 11 Oct 2016 19:22:29 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     zijun_hu <zijun_hu@...o.com>
Cc:     tj@...nel.org, akpm@...ux-foundation.org, zijun_hu@....com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org, cl@...ux.com
Subject: Re: [RFC PATCH 1/1] mm/percpu.c: fix memory leakage issue when
 allocate a odd alignment area

On Tue 11-10-16 21:24:50, zijun_hu wrote:
> From: zijun_hu <zijun_hu@....com>
> 
> the LSB of a chunk->map element is used for free/in-use flag of a area
> and the other bits for offset, the sufficient and necessary condition of
> this usage is that both size and alignment of a area must be even numbers
> however, pcpu_alloc() doesn't force its @align parameter a even number
> explicitly, so a odd @align maybe causes a series of errors, see below
> example for concrete descriptions.

Is or was there any user who would use a different than even (or power of 2)
alighment? If not is this really worth handling?

-- 
Michal Hocko
SUSE Labs