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Date: Sat, 9 Dec 2000 13:43:27 +0100
From: Rasmus Andersen <rasmus@jaquet.dk>
To: Roberto Fichera <kernel@tekno-soft.it>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm->rss is modified without page_table_lock held
Message-ID: <20001209134327.C599@jaquet.dk>
In-Reply-To: <20001208212910.E599@jaquet.dk> <4.3.2.7.2.20001209111347.00c829f0@mail.tekno-soft.it>
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In-Reply-To: <4.3.2.7.2.20001209111347.00c829f0@mail.tekno-soft.it>; from kernel@tekno-soft.it on Sat, Dec 09, 2000 at 11:25:09AM +0100
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On Sat, Dec 09, 2000 at 11:25:09AM +0100, Roberto Fichera wrote:
[...]
> >+       spin_lock(&mm->page_table_lock);
> >         mm->rss++;
> >+       spin_unlock(&mm->page_table_lock);
> >
> 
> [...snip...]
> 
> Why we couldn't use atomic_inc(&mm->rss) here and below, avoiding to wrap
> the inc with a spin_lock()/spin_unlock() ?
> 

AFAIR, because for some architectures we can't rely on mm->rss fitting in
an atomic_t. See davem's (somewhat short) post in this thread. Otherwise
search the archives for the original thread treating this problem.
-- 
        Rasmus(rasmus@jaquet.dk)

Television is called a medium because it is neither rare nor well-done. 
  -- Anonymous
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