Messages in this thread | | | Date | Sat, 09 Dec 2000 15:48:05 +0100 | From | Roberto Fichera <> | Subject | Re: [PATCH] mm->rss is modified without page_table_lock held |
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At 13.43 09/12/00 +0100, Rasmus Andersen wrote:
>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.
and At 04.32 09/12/00 -0800, David S. Miller wrote:
> Date: Sat, 09 Dec 2000 11:25:09 +0100 > From: Roberto Fichera <kernel@tekno-soft.it> > > Why we couldn't use atomic_inc(&mm->rss) here and below, avoiding to wrap > the inc with a spin_lock()/spin_unlock() ? > >atomic_t does not guarentee a large enough range necessary for mm->rss
If we haven't some atomic_t that can be negative we could define atomic_t as unsigned long for all arch, this is sufficient to fitting all the range for the mm->rss.
Roberto Fichera.
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