Re: [PATCH] mm->rss is modified without page_table_lock held

From: Roberto Fichera (kernel@tekno-soft.it)
Date: Sat Dec 09 2000 - 05:25:09 EST


At 21.29 08/12/00 +0100, Rasmus Andersen wrote:

>Hi.
>
>The following patch moves the page_table_lock in mm/* to cover the
>modification of mm->rss in 240-test12-pre7. It was inspired by a
>similar patch from davej(?) which covered too much, AFAIR. The item
>is on Tytso's ToDo list.

[...snip...]

>@@ -1076,7 +1076,9 @@
> flush_icache_page(vma, page);
> }
>
>+ 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() ?

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