linux-kernel - Re: [PATCH] mm: introduce arg_lock to protect arg_start|end and env_start|end in mm

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Message-ID: <20180324043044.GA22733@bombadil.infradead.org>
Date:   Fri, 23 Mar 2018 21:30:44 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     adobriyan@...il.com, mhocko@...nel.org, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: introduce arg_lock to protect arg_start|end and
 env_start|end in mm_struct

> So, introduce a new rwlock in mm_struct to protect the concurrent access
> to arg_start|end and env_start|end.

I don't think an rwlock makes much sense here.  There is almost no
concurrency on the read side, and an rwlock is more expensive than
a spinlock.  Just use a spinlock.