Re: [PATCH]

[Marcelo Tosatti <marcelo@conectiva.com.br>]

Rik,

Think about a thread blocked on ->writepage() called from page_launder(),
which has gotten an additional reference on the page.

Any other thread looping on page_launder() will move the given page being
written to the active list, even if we should just drop the page as soon
as its writeout is finished.

That is just _one_ case the patch will do the wrong thing (there may be
more). I suggest more investigation before actually merging the patch in
the -ac tree.

On Mon, 20 Aug 2001, Rik van Riel wrote:

> Hi Alan,
> 
> the following patch fixes reclaim_page() and page_launder() to
> correctly reactivate a page based one page->count value.
> 
> Note that we shouldn't be hitting this code very much with the
> current immediate reactivation in __find_page_nolock(), but I
> guess it would be useful to have as a safety net against things
> like the shmem code and other areas I don't about ;)
> 
> regards,
> 
> Rik
> --
> IA64: a worthy successor to i860.
> 
> 
> --- linux-2.4.8-ac7/mm/vmscan.c.orig	Mon Aug 20 11:29:24 2001
> +++ linux-2.4.8-ac7/mm/vmscan.c	Mon Aug 20 11:30:46 2001
> @@ -456,7 +456,7 @@
> 
>  		/* Page is or was in use?  Move it to the active list. */
>  		if (PageReferenced(page) || page->age > 0 ||
> -				(!page->buffers && page_count(page) > 1)) {
> +				page_count(page) > (1 + !!page->buffers)) {
>  			del_page_from_inactive_clean_list(page);
>  			add_page_to_active_list(page);
>  			continue;
> @@ -594,7 +594,7 @@
> 
>  		/* Page is or was in use?  Move it to the active list. */
>  		if (PageReferenced(page) || page->age > 0 ||
> -				(!page->buffers && page_count(page) > 1) ||
> +				page_count(page) > (1 + !!page->buffers) ||
>  				page_ramdisk(page)) {
>  			del_page_from_inactive_dirty_list(page);
>  			add_page_to_active_list(page);
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/
> 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/